# Track Car Project TTQS or Edition 30



## Msportman (Feb 18, 2006)

Decisions decisions

Never had a TT before but would only realistically buy a QS for they are rare and more track focused.

I have a lovely 2 litre 16V Golf which I've owned since 1995 which is my track car. This is tuned to just over 200bhp and has 'everything' done to it from that era although I have still kept the OE look.
It was built by Tim Stiles and runs Schrick cams a balanced 9a block 4.25 FD Quaiffe and Dave Crissel polished head. Slick 50 Kjet set up to compliment the split duration cams.It's a great car which I will hand on to my son.

I have recently bought a low mileage 3 door ED30 with DSG and it's boggo standard. I have owned 2 ED30's previously and know what to do with these and their potential but as usual it's thousands of pounds worth of bits to get to a nice road and track weapon. Time you go APR Stage 2 + put some KW Clubsports on with anti lift together with a diff big brakes Intercooler and stick rubber and wheels you're up to £8k+...ooch!!

Before I bought the car I did try a QS and this although standard was a lovely thing to drive but unfortunately I had placed a deposit on the ED30.

Hence I am thinking of selling the ED30 and buying a TTQS and taking a trip up to APS and speak to Ed and Nathan and perhaps run one for track and put some decent rubber and brakes. I don't know how the QS maps....I assume it's like the 225 and you can get to approx 265bhp??

The OE seemed pretty good but again I didn't drive it in anger but turn in impressed me.

Any thoughts or experience with the QS as a proper track car??


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## brushwood69 (Dec 17, 2012)

The QS is the same as the 225 TT apart from some minor mods (and a price hike!) I'm not an expert on the QS but do race a TT.

Less weight via removal of counter balance (and aircon?) 
battery relocated to rear
Remap to 240bhp
Optional bucket seats?

You will still need to uprate suspension and steering(cookbots) to dial out understeer, add bigger brakes, remove a lot a weight and then mod the engine/turbo/exhaust

BW


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## NickG (Aug 15, 2013)

As BW said, if you're planning on a car solely for the track, get a 225, save yourself £4k and spend this extra cash on the suspension and brakes to get it much better than a QS in terms of handling!

Then strip it out as the TT's major enemy, including the QS, is weight!!!

QS purists will probably agree too, as they wont want to see a limited edition QS being molested and driven around a track :lol: (Although this may put the value of their own up slightly!)


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## Lhasa2008 (Dec 28, 2014)

Interesting question 

I've not got experience of driving either a ed30 or QS(!), but if I had to choose I would think the newer tfsi engine ed30 would be a stronger engine than the QS, which should mean a more reliable track day engine.

However the QS should be lighter and the 4wd much better at getting on the power early out of bends.

Price wise a good QS would be similar price to a Ed30, so for me it would be down to which will be the most fun on track, so for me that would be a light weight good handling QS, rather than big powered heavier ed30.

Ultimately if you find a QS with a broken engine, I bet a TFSI engine swap would be awesome 

(Nice spec Golf btw, I've also got a Dave Crissel head in mine :wink: )


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## Gonzalo1495 (Oct 13, 2014)

NickG said:


> As BW said, if you're planning on a car solely for the track, get a 225, save yourself £4k and spend this extra cash on the suspension and brakes to get it much better than a QS in terms of handling!
> 
> Then strip it out as the TT's major enemy, including the QS, is weight!!!
> 
> QS purists will probably agree too, as they wont want to see a limited edition QS being molested and driven around a track :lol: (Although this may put the value of their own up slightly!)


You guys and your weight reduction lately :lol:

I think I've shredded off roughly 250lbs off my car so far. Or for you guys around 110kg. Removing the spare helps, and I haven't even removed the counter weight yet lol.
Good link for easy weight saving: http://forums.vwvortex.com/showthread.p ... T-s-weight


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## NickG (Aug 15, 2013)

It's free everything!

Handling improved, braking improved and acceleration improved... Why WOULDN'T you attack this first?! :lol:


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## Gonzalo1495 (Oct 13, 2014)

NickG said:


> It's free everything!
> 
> Handling improved, braking improved and acceleration improved... Why WOULDN'T you attack this first?! :lol:


It's costly as hell, and diminishes the value of the car. That's why I still have my rear seats in/carpet. Otherwise I'd be driving a tin can if I could :mrgreen:


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## NickG (Aug 15, 2013)

Unless I'm missing something, removing bits costs no money?!

You can make money on selling the bits though!!!

And the OP is asking about a "Track Car Project"... Track cars will de-value once you start tinkering, that's a fact.


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## Lhasa2008 (Dec 28, 2014)

NickG said:


> Unless I'm missing something, removing bits costs no money?!
> 
> You can make money on selling the bits though!!!
> 
> And the OP is asking about a "Track Car Project"... Track cars will de-value once you start tinkering, that's a fact.


Which is why buying a well spec'd track car that someone else has spent their own money on rather than your own is a good idea!


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## KarlD (Jul 23, 2015)




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## NickG (Aug 15, 2013)

Definitely!!! If your not bothered about the build itself then that's a great idea!!


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## NickG (Aug 15, 2013)

KarlD said:


>


 :lol: :lol: :lol: :lol: :lol: :lol:

:roll:


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## Gonzalo1495 (Oct 13, 2014)

NickG said:


> Unless I'm missing something, removing bits costs no money?!
> 
> You can make money on selling the bits though!!!
> 
> And the OP is asking about a "Track Car Project"... Track cars will de-value once you start tinkering, that's a fact.


Well that's not the half of weight reduction I'm referring to. :wink:

Removing heavy oem seats = buying new racing seats which are at a bare minimum $600 (off brands)
Removing heavy oem side skirts = buying pricey new ones (reigers which are the lightest I believe are super expensive)
Removing heavy oem wheels for aftermarket = yeah we all know this all too well :lol:

list goes on and on. Yeah you can recoup some money back with selling old parts, but if you get into the deep waters of weight reduction you will have to upgrade to aftermarket parts (carbon fibre hatch/bonnet as well for example) which can be ridiculously pricey.


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## NickG (Aug 15, 2013)

Maybe so, but I was referring to the 100kg-150kg of free weight reduction you can get.

For a track car, I'd expect to see new seats anyway, heated leather recliners aren't very supportive for the track!! That's gives an easy 200kg of weight saved, without doing anything drastic.

Or you can spend £800 on a BBK, £1500 on engine mods and £1500 on suspension mods and carry all the free weight around :roll:


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## Von Twinzig (Feb 10, 2014)

Gonzalo1495 said:


> NickG said:
> 
> 
> > As BW said, if you're planning on a car solely for the track, get a 225, save yourself £4k and spend this extra cash on the suspension and brakes to get it much better than a QS in terms of handling!
> ...


I'm at 1240kg with a/c, but that's staying.

My mate Stephen on the other forum has a 964 which he is working on. Target weight for that is 964kg. He's an ex Ferrari F1 composites design engineer so there's a lot of CF in his future. If he'd not gutted it, it would be worth £35 grand now so he's clearly way past worrying about the things value :?

VT


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## KarlD (Jul 23, 2015)

I don't understand this thread.

The OP is asking a question about a track car.
Any half decent track car will have buckets, harnesses, cage, coils, wheels, tyres.
QS was a car to kick a bit of interest back into an aging marque.

If you want to make a track TT, first find a car that has the engine/drive config that you fancy playing with (because that's all we are doing at the end of the day - playing) so 1.8T FWD, Quattro or V6, and find one that has as few miles on and best history you can afford.
Then do it in this order, wheels and brakes, coilovers, mild weight saving (stereo, a/c, carpets, trim), seats with harnesses + either harness bar or cage. Further weight saving depends on installed safety devices. Then power.


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## KarlD (Jul 23, 2015)

Track cars are money pits. They'll never be worth to anyone else what you spend on them, but to you they'll be worth more.


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## Gonzalo1495 (Oct 13, 2014)

NickG said:


> Maybe so, but I was referring to the 100kg-150kg of free weight reduction you can get.
> 
> For a track car, I'd expect to see new seats anyway, heated leather recliners aren't very supportive for the track!! That's gives an easy 200kg of weight saved, without doing anything drastic.
> 
> Or you can spend £800 on a BBK, £1500 on engine mods and £1500 on suspension mods and carry all the free weight around :roll:


Yeah I agreed with you on that bro lol. That's why I've done most of that as well.

Yeah definitely, I'm just saying in the long it can get very costly is all. And soon it becomes a downward spiral.


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## Msportman (Feb 18, 2006)

KarlD said:


> I don't understand this thread.
> 
> The OP is asking a question about a track car.
> Any half decent track car will have buckets, harnesses, cage, coils, wheels, tyres.
> ...


Interesting replies.

Only reasons for the QS was it already has some weight out it and it was only going to be a light track build as I wouldn't want to rip it apart to the point of no carpets dash etc. I wanted a quick road and track weapon and I suppose the ultimate track car's don't fit the road use criteria. Hence a well sorted FWD ED30.

I ran one before and got to 370bhp ran big brakes Quaiffe KW Clubsports anti lift and track rubber. It was quick but it was a manual car so I'm not sure if DSG can handle serious track abuse.

Until reading VT's thread and the amount of weight they carry and the pesky Haldex woes it puts me off somewhat.

I am sure I would upset TT purists playing and ripping apart a QS hence the normal 225 car would be an ideal place to start.


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## KarlD (Jul 23, 2015)

I've been thinking about this.

Buy the QSTT. I don't see why you wouldn't if you can afford to. They're not worth THAT much in the grand scheme of things and you'd feel pretty smug having one lol. It's hardly lightweight at 1379kg, but it's not slow and there is of course plenty of power left in that engine.

All you would really need to make a decent sorted road car that'll hold its own on the track would be a decent set of coilovers, adjustable tie bars and drop links (properly set up, not just dropped on its arse), good rubber and a decent brake pad compound. Lightweight alloys would further improve things. Full stainless system - because it would be rude not too.

Alloy flywheel and performance clutch...

The stock seats are Recaro Poles I believe. If you wanted to you could run harnesses with these without issues. However, you would need a proper harnesses bar as a minimum, as that cargo bar is not strong enough for harnesses to run to. You NEED to use a harness bar with those seats as they do not have reinforced backs. VT has a sexy harness bar. Other than that, bolt in rear cage. Both of these options would require a little bit of trim cutting, but done well this can look pretty swanky.

You could remove the OEM belts and fit 4 point harnesses with a quick release push button buckle and these would be 100% road legal. However I would strongly recommend that you get a set with the ASM system.

I think it would be a cool project. Certainly having a nice base car will keep you focused on fitting only quality parts with will only add to the perceived value of the thing.


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## NickG (Aug 15, 2013)

^^^^This if fast road car and not going crazy ^^^

Not this if all out Track weapon... Dead money for no benefit.


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## VdoubleU (Jan 29, 2015)

Or you could buy a 225 quattro. Take the rear seats out and you've basically got a QS any way :lol:

Please don't kill me QS lovers


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## Rich196 (Mar 31, 2011)

Or just buy something rwd 

Sent from my HTC One M9 using Tapatalk


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## Thistlebeeace (Oct 15, 2014)

Rich196 said:


> Or just buy something rwd


Glad someone else said what I was thinking. I know track days aren't free-for-all-drift-sessions, but I'm always a touch confused by any track project which is AWD or FWD. Not saying that anybody wouldn't have fun, it's just not where I'd think to start from as RWD should always ultimately be _more_ fun. Unless the track days are run on gravel or snow. I guess YMMV on that outlook though.

I'd use a standard 225 by the way, FWIW. The QS mods make them a lovely road car, but it's really just touchy feely stuff and I suspect you could go way beyond that without having made the extra initial outlay.


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## NickG (Aug 15, 2013)

Well, you look at the CSCC that I went to watch a few weeks back, most series dominated by RWD, and it has to be said, M3's for the majority.

But then you look at Time Attack and the top is dominated by AWD Evo's and Scoobs.

Then there is the BTCC with Type-r's and MG's both FWD.

I guess it's about how well you can get the power down!

Either way, the biggest factor will be the driver... None of us are Hamilton,or Plato, so learn to drive properly and you'll become faster in what ever you drive.


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## Madmax199 (Jun 14, 2015)

Thistlebeeace said:


> Glad someone else said what I was thinking. I know track days aren't free-for-all-drift-sessions, but I'm always a touch confused by any track project which is AWD or FWD. Not saying that anybody wouldn't have fun, it's just not where I'd think to start from as RWD should always ultimately be _more_ fun. Unless the track days are run on gravel or snow. I guess YMMV on that outlook though.


I am confused by this idea that RWD is somehow "more fun" or superior to AWD on a track. Have we forgotten that Audi made a name for themselves in the racing world in the late 80's by destroying the RWD status quo? So much so that they got banned from many open racing series in the 90's for having an "unfair" advantage.

The problem IMO, with the way you guys compare AWD vs RWD or FWD in forums, seems that racing and tracking is blended by the collective into one concept. Tracking is meant to have fun with whatever you have, so fun is often preferred over all out time. Racing on the other hand is all about putting the fastest possible time on the clock every lap, this exercise could care less about if there is any fun into setting said fast lap time. It's more about whatever it takes within the ruleset with racing and race cars. When looking at going fast at the track a few main things are usually put on the table:

1) Power/weight ratio
2) Tire (or traction)/weight ratio
3) Dowforce/speed ratio

With number two on that list, AWD always has a big advantage over the other layouts (RWD and FWD). If all else is equal, an AWD machine is far superior than a RWD one any day and in any conditions. That is also why most open classes have weight equalizers to allow FWD and RWD cars to have a chance with their AWD counterparts. So, to put an end to this nonsensical idea that RWD is better on track than AWD, it is NOT. More fun maybe, but that's not the point in racing.

Watch this awesome video about Audi, and the debue of AWD in racing. 







NickG said:


> Well, you look at the CSCC that I went to watch a few weeks back, most series dominated by RWD, and it has to be said, M3's for the majority.
> 
> But then you look at Time Attack and the top is dominated by AWD Evo's and Scoobs.
> 
> ...


Series are always dominated by cars that can make the most out of the specific ruleset for the duration of the race. Time attack is about building the badest/fastest car to turn a lap, so AWD naturally always dominate the open class. Can't escape physics...


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## NickG (Aug 15, 2013)

Can't disagree with any of the above!!

With the TT the trick is going to be getting the AWD system and Haldex working as well as possible for the track, as I've said before, once you do this, I believe it will be an awesome machine!!


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## Madmax199 (Jun 14, 2015)

NickG said:


> Can't disagree with any of the above!!
> 
> With the TT the trick is going to be getting the AWD system and Haldex working as well as possible for the track, as I've said before, once you do this, I believe it will be an awesome machine!!


The thing Nick is that the AWD sytem and Haldex are already working as well as possible. With a sorted suspension, ideal rubber size for the power and weight of the car, 50% rear TQ split is all that is needed. Getting the system to react quickly enough is a mapping and sofware issue in the haldex control module. Get a haldex remap, or an upgraded performance-oriented haldex controller and it's all handled in the haldex front. IMO, what really need upgrading are the car's supension, and most importantly, the way people drive a front biased AWD car. The loose nut behind the wheel , and lack of suspension tuning is what seems to be the common problem with tracking a TT.

Simple example, how many here have optimized their spring rates, shock valving, added enough rubber to support such a heavy car, and then drove them properly (point and shoot, and Left-foot-braking) ? If you can find a handful of members, I can guarantee you that they all think that the TT is an Awesome track weapon.

To put it all in perspective, I track my TT roadster and as of lately I have a 1,100 Kg race weight, 315mm and 315mm race rubber, 800/1300 lbs springs, custom revalved coilovers, corrected camber, corrected roll center, corrected caster. To be completely honest, I still think that at my weight, the car could use more tire to be 100% sorted. My plan is to go with 16x12" wheels and 345mm bias ply race tires when the budget allows. Do you thing all the people complaining that the TT is not a good track weapon have done any of this? The answer is no, and that's why they are downplaying the TT's track ability... because I'm not.


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## NickG (Aug 15, 2013)

Yes, that's what I meant by needs sorting, an updated controller is a must. I believe this also means you can use it as an advantage under braking, when the standard software reverts to FWD only? By all accounts as standard it can be very twitchy, especially in the wet, as it can kick in when it wants!

Interesting regarding spring rates... We were looking to go 500/800lbs which will give roughly a balanced 500lbs overall. You appear to have gone for 800lbs balance... Any reason for this?


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## Thistlebeeace (Oct 15, 2014)

Madmax199 said:


> I am confused by this idea that RWD is somehow "more fun" or superior to AWD on a track. Have we forgotten that Audi made a name for themselves in the racing world in the late 80's by destroying the RWD status quo? So much so that they got banned from many open racing series in the 90's for having an "unfair" advantage.


I said it was more fun, not superior. AWD is an advantage to acceleration wherever you are traction limited - be that by power output, tyre performance or surface condition. It sure seemed to work for the latter reason in the WRC, and by the former two in the Trans Am series (and sweet baby jesus the IMSA GTO is my favourite of all Audis).



Madmax199 said:


> The problem IMO, with the way you guys compare AWD vs RWD or FWD in forums, seems that racing and tracking is blended by the collective into one concept. Tracking is meant to have fun with whatever you have, so fun is often preferred over all out time. Racing on the other hand is all about putting the fastest possible time on the clock every lap, this exercise could care less about if there is any fun into setting said fast lap time.


Agreed on both of those points. And as we're talking about track days, not racing, I was talking about 'fun', not ultimate lap times.



Madmax199 said:


> It's more about whatever it takes within the ruleset with racing and race cars. When looking at going fast at the track a few main things are usually put on the table:
> 
> 1) Power/weight ratio
> 2) Tire (or traction)/weight ratio
> ...


Never said it was better - just more fun. But in a racing class where you are _not_ traction limited, what exactly is the advantage of carrying an AWD system? Most paved track racing vehicles, no matter how powerful they are, generally _aren't_ traction limited. The Nissan GT-R goes racing without its fancy AWD system and does just fine. It might be compelled to do so by regs (not really sure) and might therefore lack a wet weather advantage it might otherwise have, but AWD was considered the next big thing in F1 as early as the late 70s, until those trying it determined that it simply wasn't worth the weight penalty. Front torque distributions fell as low as 10% when throttle on understeer compromised lap times.

Anyway, back to track days. They're about driving your car quickly. If your measure of how much enjoyment you get out of the track day is what the fastest lap time you set is, then that's fine - almost doesn't matter if you had fun or not - or how you achieved it. Have at it, in anything you like.

If your measure isn't this, but is more about exploring/exploiting your car's handling envelope and how it responds to longitudinal demands (i.e. brake and throttle), I firmly believe you are more likely to 'have fun' in a RWD car. AWD generally has a stabilising effect on vehicle handling. RWD will generally have a destabilising effect. Managing the destabilising effect is what is 'fun' - in my opinion. If that - in your opinion - is an undesirable barrier to a faster lap time, then AWD may be more appealing to you on track.


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## Madmax199 (Jun 14, 2015)

NickG said:


> Interesting regarding spring rates... We were looking to go 500/800lbs which will give roughly a balanced 500lbs overall. You appear to have gone for 800lbs balance... Any reason for this?


Let me first say that there are various school of thoughts when tuning suspension. With that said, the concensus is to always go for higher rear natural chassis frequency. Why? Simply because when you set it square like you mentioned with a 500lbs spring rate balance, the car tend to never completely take a set when cornering. Moving in a forward direction, everything happens first to the leading axle (which happens to also be in charge of steering) of a car. As a result, any movement in the suspension will be happening in the front, and shortly after, the it's the rear's turn. Therefore, in order to have a car that takes a set quickly, you anticipate and bump the rear Natural Frequency so the car is optimized to have front and rear axles take a set simoultaneously (at least as close as possible, and obviously you can only fully optimize for a fixed speed).

For reference, my front Natural frequency is around 2.5 Hz while my rear is around 3 Hz. When that converts to wheel rate or spring rate (and accounting for the lower 0.63 rear motion ratio), you get spring rates that are distributed like I mentioned. Hope this helps!


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## Thistlebeeace (Oct 15, 2014)

Madmax199 said:


> the concensus is to always go for higher rear natural chassis frequency.


Disclaimer - I am not trying to be a berk - just clarify where I feel able to. Unbelievably, I am paid to do stuff related to this topic (suspension, not being irritating on forums).

A ride ratio (rear:front ratio of axle natural frequencies) of more than 1.0 was first coined by Maurice Olley and is almost exactly for the purposes you described, just not to do with cornering. The idea of making the rear axle frequency higher than the front is to make the heave oscillations 'line up', so after passing over a bump, the car is moving purely vertically. If you had the same frequency front and rear, the car would pitch - at worst, you would have the front axle moving downwards as the rear moves upwards. Both axles moving in the same direction feels much better than the opposite direction.

Once the springing is set, cornering behaviour can be further fiddled by adjusting front/rear ARB stiffnesses and damping.


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## Madmax199 (Jun 14, 2015)

Thistlebeeace said:


> I said it was more fun, not superior. AWD is an advantage to acceleration wherever you are traction limited - be that by power output, tyre performance or surface condition. It sure seemed to work for the latter reason in the WRC, and by the former two in the Trans Am series (and sweet baby jesus the IMSA GTO is my favourite of all Audis).
> 
> Agreed on both of those points. And as we're talking about track days, not racing, I was talking about 'fun', not ultimate lap times.
> 
> ...


Well, let's take superior out of the discussion since we seem to be in agreement that AWD is superior (I quoted your post to make my initial argument, but was really talking about the general view that AWD as a platform is at a handicap vs RWD). And BTW, traction is always limited, or never unlimited if you like (regardless of surface and platform). The minute you start rolling and cornering at the track, traction goes from 100% of what it was statically to lower percentage -- an undeniable fact.

Fun seems to be a subjective gray area that, using you and I as a sample, can mean different things to the individual. I am by no mean a professional racer, but very competitive. Fast to me is setting the fastest possible lap time, if that means doing so neutrally, understeering, or oversteering, it does not matter, fast is what counts. I can tell stories of many modifications where the car felt more "fun" and enjoyable to toss around, but also taxed the lap times, those to me are not what I call fun. Different people, different strokes I guess. Cheers!


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## Madmax199 (Jun 14, 2015)

Thistlebeeace said:


> Madmax199 said:
> 
> 
> > the concensus is to always go for higher rear natural chassis frequency.
> ...


I totally agree, and will never see a respectful exchange in ideas been jerky. My question to you is how do you ideally set said springing? Yes, the bars and damping can be used to do final triming, but the springing must also be done correctly.


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## Thistlebeeace (Oct 15, 2014)

Madmax199 said:


> Fun seems to be a subjective gray area that, using you and I as a sample, can mean different things to the individual. I am by no mean a professional racer, but very competitive. Fast to me is setting the fastest possible lap time, if that means doing so neutrally, understeering, or oversteering, it does not matter, fast is what counts. I can tell stories of many modifications where the car felt more "fun" and enjoyable to toss around, but also taxed the lap times, those to me are not what I call fun. Different people, different strokes I guess. Cheers!


Amen to that - looks like we represent two extremes of track driving! And FWIW, I believe neither of us is wrong. I also participate in a work karting league and my outlook in that is the complete opposite of how I view track days - because it's timed/pointed etc.



Madmax199 said:


> Well, let's take superior out of the discussion since we seem to be in agreement that AWD is superior (I quoted your post to make my initial argument, but was really talking about the general view that AWD as a platform is at a handicap vs RWD). And BTW, traction is always limited, or never unlimited if you like (regardless of surface and platform). The minute you start rolling and cornering at the track, traction goes from 100% of what it was statically to lower percentage -- an undeniable fact.


My specific meaning of 'traction limited' is the ability to use 100% of the engine output without wheelspin. Yes, once you start asking for lateral grip from a tyre, the amount of traction you can access is reduced, but even a 200-300bhp road car on a dry track can _probably_ take full throttle in most circumstances without breaking traction. It's in those circumstances that I'd argue that the advantage of AWD is at its minimum (so not so superior). Give the same car 500bhp or put it on gravel (or even a wet track) and the situation is very different (potentially quite a lot superior)!


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## Thistlebeeace (Oct 15, 2014)

Madmax199 said:


> I totally agree, and will never see a respectful exchange in ideas been jerky. My question to you is how do you ideally set said springing? Yes, the bars and damping can be used to do final triming, but the springing must also be done correctly.


Phew - glad I haven't come across too badly (the internet masks my natural charm  ).

The annoying answer which can be used for almost any suspension related question is - 'it depends'. There are no particularly right or wrong answers regarding suspension setup, because 'it depends' on what you're trying to achieve.

For a *normal* road car, you'd probably want something in the range of 1.0-1.4Hz front axle frequency with a ride ratio of about 1.15 - 1.2 (so your rear frequency range would be about 1.15Hz - 1.7Hz). Where you decide to go for in that range depends on if you're trying to make a car feel relaxed/comfortable (lower frequency) or taut and sporty (higher frequency). Ever driven a Citroen on hydropneumatic suspension? They feel quite floaty, and that's because that technology isn't really given to producing frequencies higher than 1.0Hz - but it's fine for the type of vehicle character/type of usage they're going for. Conversely, some of the Audi S-Line packages are definitely at the higher end of the range and can feel quite tough - although the trade off is that they feel more alert when twirling the wheel. It isn't much more complicated than that!

I'd be surprised to find a production road car as high as 2.5/3.0Hz because that's more than many punters would tolerate - however, as an informed choice by yourself, it's giving the car the kind of response you'd prefer. Which is good! It also allows you to run a ton of damping without resulting in odd behaviours (too much damping for a given spring isn't nice). All very good for the track.

Your springing for ride frequencies naturally gives you an amount of roll stiffness on each end. Normally this isn't enough to control roll to a level we find acceptable these days, so that's why you then make up the rest of the roll stiffness with anti roll bars.

The handy thing about ARBs is that you can make them much stiffer or softer at each end of the car to tune the handling balance to the desired level. Stiffer at one axle tends to reduce the amount of grip at that end. The only 'right' answer as to how stiff to make them relative to each other is whatever gives the balance (understeery, neutral, oversteery) that you want. They're very effective, because they're normally a large proportion of the stiffness at the wheel (in roll). With the spring rates you're running this is obviously a lower proportion, but still significant.


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## KarlD (Jul 23, 2015)

Thistlebeeace said:


> Madmax199 said:
> 
> 
> > I totally agree, and will never see a respectful exchange in ideas been jerky. My question to you is how do you ideally set said springing? Yes, the bars and damping can be used to do final triming, but the springing must also be done correctly.
> ...


When I eventually get the correct privileges to send PM you may well be receiving a few from myself lol. Unfortunately I am not one for posting comments on how shiny bright someone's exhaust tips look etc so this may take a while...

I chose 500lbs wheel rates for Nick's car as a bit of an educated guess. I was in the mind of having a frequency of around 2.5hz and arrived at 500lbs by guessing the sprung weight and rounding stuff up! Rear frequency is probably significantly higher with these rates so it'll probably catch up too quickly. But working with extreme numbers will help me work out what effects it has on the car??? Perhaps. Trial and error may play a big part in this... I need to do more reading into the subject as its something that I am very keen on trying to get a grip on, but most of the literature I find/have is a bit out of my depth.


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## NickG (Aug 15, 2013)

To be honest, I was just amazed that you can read!!


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## KarlD (Jul 23, 2015)

^^ this person makes cracks like this yet is going to be relying on me for a great number of bolts being tightened on his car...


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## Madmax199 (Jun 14, 2015)

Thistlebeeace said:


> Phew - glad I haven't come across too badly (the internet masks my natural charm  ).
> 
> The annoying answer which can be used for almost any suspension related question is - 'it depends'. There are no particularly right or wrong answers regarding suspension setup, because 'it depends' on what you're trying to achieve.
> 
> ...


I am glad we are a big happy family with the discussion. We can all agree that the rear Natural Frequency (with performance in mind) needs to be higher than the front by a certain percentage. The question I asked about how springing should be done was a rhetorical one, but your answer demonstrates how there should be some rear frequency bias. Focussing on track setup, I believe that tires, surface, and aero should dictate the upper limit of what is acceptable or optimal. This solves the question asked earlier about having a square Natural Frequency.

Now, the plot thickens. I have a real question.  You said something very interesting, bars tend to remove grip on the end they're fitted as their rate increases. And I totally agree with your statement since I preach the same thing on a regular basis. Now my question is why would anyone tuning suspension use anti roll bars at all if the spring alone can provide the proper roll control (while staying well within acceptable Natural Frequency)?

I am asking this because the logic in this community is bars are a must. And some even go as far as adding stiffer bar to the front of a TT when all it does is remove available grip to that end (making it even more prone to understeer). In my car, I ran without a front bar and let the springs alone take care of the roll control. The result is that the dreaded terminal understeer is totally eliminated. Why do this community insist on going against what works in their favor?

Same goes for the rear too. I see people blindly adding the stiffest possible rear bar they can put their hands on for track duties -- not acknowledging that stiff rear bar induces tripod and makes putting power down a daunting task (once you pick up that inside rear wheel, all the load is instantly transferred to the already-struggling outside front and there is even more understeer). In my car I have tried all type of combinations and bar rate. The best in terms of measured lateral G forces (both peak and average) have been with the stock rear bar. The reason it's not also deleted is that ironically I am at the limit usable Natural frequency for my tires, surface, and amount aero grip.

Is it a lack of knowledge or general internet folklore being passed on from one drone to the next?

Pic of dreaded tripod motion that the TT tend to get into when racing (it gets worse the stiffer the rear ARB gets:


















Here are the two best rear ARB I have tested. Stock TT bar with extra adjustment hole and R32 bar with extra adjutment hole added as well. The TT bar gave the best results (lap times and recorded g-force by datalogger), so it became the default bar I use.


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## Von Twinzig (Feb 10, 2014)

Madmax199 said:


> NickG said:
> 
> 
> > Can't disagree with any of the above!!
> ...


MM, your car^^^^^^^^^^^^^^^^^^^^^^^^ do you drive or trailer it to the track?

VT


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## Madmax199 (Jun 14, 2015)

My car is still driven to events and back, but lately it's getting more and more like a car that has to be trailored. The interior is completely stripped and it attracts a lot of attention (although registered, inspected, and insured). Getting near my 1,000 kg goal, and soon replacing the windscreen with Lexan, I think it is going to be a trailor queen by next year.

That's what my interior view is like nowadays. I feel strapped in a coffin driving the thing to events


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## 1781cc (Jan 25, 2015)

Thistlebeeace said:


> AWD was considered the next big thing in F1 as early as the late 70s, until those trying it determined that it simply wasn't worth the weight penalty. Front torque distributions fell as low as 10% when throttle on understeer compromised lap times.


To be fair AWD tech wasn't what it is today, a system derived from the one in Ferrari's FF would be ideally suited to F1 and provide a much better weight setup. In the late 70s/80s they didn't have the electrical know-how they do now and all AWD systems where mainly mechanically based deals, hence the major weight.

This thread is amazing to read, and poses a lot of questions. I have been weighing up costs to start my project (which was meant to be in full swing by now) but took a back seat while I sorted my cabriolet out. Now I am wondering if I should scrap my plans, sell the TT and buy a ready made track car from piston heads... [smiley=argue.gif]


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## Madmax199 (Jun 14, 2015)

1781cc said:


> Thistlebeeace said:
> 
> 
> > AWD was considered the next big thing in F1 as early as the late 70s, until those trying it determined that it simply wasn't worth the weight penalty. Front torque distributions fell as low as 10% when throttle on understeer compromised lap times.
> ...


An already made track will always be much cheaper and easier than building one. However, half the fun and rewards is in the build process. I always have as much fun building my cars as I do racing them. It's like a science project and your personality, knowledge and craftmanship all collide to make it what it is. It's definitely not for everybody, but the building process is what make it yours and not feel like some long term rental.


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## Gonzalo1495 (Oct 13, 2014)

Madmax199 said:


> Here are the two best rear ARB I have tested. Stock TT bar with extra adjustment hole and R32 bar with extra adjutment hole added as well. The TT bar gave the best results (lap times and recorded g-force by datalogger), so it became the default bar I use.


But Max, everyone on the forum wants 29mm rear arbs!! :roll:

lol in all seriousness, that's very surprising. I assume that the R32 bar still allowed for less understeer than the 14mm TT one right?

Edit: And since you're from the states too, that R32 bar is the 16mm one, not the 19mm Euro one correct?


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## Madmax199 (Jun 14, 2015)

Gonzalo1495 said:


> But Max, everyone on the forum wants 29mm rear arbs!! :roll:
> 
> lol in all seriousness, that's very surprising. I assume that the R32 bar still allowed for less understeer than the 14mm TT one right?
> 
> Edit: And since you're from the states too, that R32 bar is the 16mm one, not the 19mm Euro one correct?


Well, that is the point that we are trying to make. ARBs intrinsically *remove* grip on the end tbey are fitted, so when you fit a big rear bar, all you do is make the the rear less grippy and force it to slide before the front end does. This exercise gives a false sense that understeering is improved, but in reality you have not improved the front end that created the understeer. You just masked it by un-sticking the rear to change the balance, and total grip is less than where you originally started (so a less grippy and slower car overall at the track).

More/stiffer bar = Less grip -- Less/softer bar = more grip. Therefore the less used, the better off you are in terms raw grip. I liked the US 15mm R32 bar because it provided an improvement over an aftermarket 21mm that was tossed on there for testing. The TT 14mm rear bar is the best however as it intervenes less with rear suspension independence and doesn't take away precious grip out of the rear.


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## Gonzalo1495 (Oct 13, 2014)

Madmax199 said:


> Gonzalo1495 said:
> 
> 
> > But Max, everyone on the forum wants 29mm rear arbs!! :roll:
> ...


Okay now I understand how they work! That makes me a lot happier that I ordered the US R32 Bar then. Thanks for the insight as always


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## KarlD (Jul 23, 2015)

^ I love that. Ordered an ARB as an "upgrade" (one would assume) without actually understanding the principal of how they work.
That's not a dig at the individual BTW. Certainly not. Just typical of forum culture doing its thing, stiffer is better, lower is better, R888s for a daily etc etc.


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## Gonzalo1495 (Oct 13, 2014)

KarlD said:


> ^ I love that. Ordered an ARB as an "upgrade" (one would assume) without actually understanding the principal of how they work.
> That's not a dig at the individual BTW. Certainly not. Just typical of forum culture doing its thing, stiffer is better, lower is better, R888s for a daily etc etc.


I meant more so I understand how they impact the car now and not just going off the final result. I knew the outcome it would have on the car before I purchased it. That's why I bought a size similar to OEM standards instead of the beefy ones everyone believes help the car. I like learning the dynamics behind how things work when I get the chance so you can bet I'll thank Max for the lessons everytime :wink: Not to say you're totally not spot on with your comment though haha.


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## NickG (Aug 15, 2013)

If you made the perfect forum car...

Toyo R888's
27mm rear ARB
K-sport 12 pot callipers with 400mm drilled slotted and grooved discs
19" BBS speedlines
4" straight through exhausts with a 50 cell sport cat (gotta keep it legal)
Recaro seats
Baileys dump valve (for the old skool tuners)

A wise man once said;



> "a camel, is a horse designed by a committee"


One of my favourites!


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## KarlD (Jul 23, 2015)

NickG said:


> If you made the perfect forum car...
> 
> Toyo R888's
> 27mm rear ARB
> ...


Don't forget Black Series Power Flex bushes!


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## Von Twinzig (Feb 10, 2014)

1 out of 8's not a bad average I guess :lol:

VT


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## NickG (Aug 15, 2013)

:lol: I know you're a great promoter of 12 pots VT!


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## Thistlebeeace (Oct 15, 2014)

Madmax199 said:


> Now, the plot thickens. I have a real question.  You said something very interesting, bars tend to remove grip on the end they're fitted as their rate increases. And I totally agree with your statement since I preach the same thing on a regular basis. Now my question is why would anyone tuning suspension use anti roll bars at all if the spring alone can provide the proper roll control (while staying well within acceptable Natural Frequency)?


The reason is that you generally can't obtain sufficient roll stiffness from just your springs, without sending the axle frequencies sky high. ARBs allow you to increase roll stiffness without having to go higher on axle frequencies - which might not be desirable, depending on what you're trying to achieve. In terms of roll stiffness, they do exactly the same things as springs. 2500Nm/deg of roll stiffness is 2500Nm/deg of roll stiffness, no matter how it's derived. Stiff axles create more lateral load transfer, which reduces grip. Doesn't matter what bits make it stiff.

The other reason to use ARBs is that you may not be able to achieve the roll stiffness distribution (front:rear) which will give you the handling balance you desire if only relying on the springs. Imagine, say a 1000kg car (sprung mass) with 50% of the weight on the front axle. If you wanted axle frequencies of, say, 1.25Hz front and 1.5Hz rear, your springs would be (using f= 1/2pi x sqrt(k/m)):

Front: k = f^2 x m = ((1.25 x 2pi)^2 x 500)/(2x1000) = 15.4 N/mm at the wheel
Rear: k = f^2 x m = ((1.5 x 2pi)^2 x 500)/(2x1000) = 22.2 N/mm at the wheel

All else being equal that'd give you 41% of your roll stiffness on the front axle. This is a lot less than you'd need for the car to be stable and allow you to 'lean' on it. Adding a front ARB of about 15N/mm extra at the wheel would take that to 58%, which is much more manageable.

Conversely, if you had 70% on the front, you'd have:

Front: k = f^2 x m = ((1.25 x 2pi)^2 x 700)/(2x1000) = 21.6 N/mm at the wheel
Rear: k = f^2 x m = ((1.5 x 2pi)^2 x 300)/(2x1000) = 13.3 N/mm at the wheel

And sans ARBs, that'd give you 62% front roll stiffness - which might be a bit too much. A bar adding 3 N/mm to the rear wheel rate would take that down to about 57%.

A range of about 52%-58% front roll stiffness is a 'sensible' number - although 'sensible' might be too sensible for you on track.



Madmax199 said:


> I am asking this because the logic in this community is bars are a must. And some even go as far as adding stiffer bar to the front of a TT when all it does is remove available grip to that end (making it even more prone to understeer). In my car, I ran without a front bar and let the springs alone take care of the roll control. The result is that the dreaded terminal understeer is totally eliminated. Why do this community insist on going against what works in their favor?
> 
> Is it a lack of knowledge or general internet folklore being passed on from one drone to the next?


There's no evil in ARBs - they're a very handy way to tune the handling balance. Sure, going too stiff on the front will induce understeer, and going too stiff on the rear may cause wheel lift (and more understeer), if it hasn't already induced enough oversteer to make the car spin. The crux is though, that no matter how you derive your axle roll stiffness, if it's too stiff at one end vs the other, the above behaviours are likely to happen.

The advantage of ARBs over doing it by springs is merely that you can tune the amount of roll stiffness (how much it rolls), and the roll stiffness distribution (handling balance) *independently* of the ride frequencies.


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## Thistlebeeace (Oct 15, 2014)

1781cc said:


> Thistlebeeace said:
> 
> 
> > AWD was considered the next big thing in F1 as early as the late 70s, until those trying it determined that it simply wasn't worth the weight penalty. Front torque distributions fell as low as 10% when throttle on understeer compromised lap times.
> ...


Yes - I think the prevailing technology available at the time was 'normal' fixed torque splits via epicyclic centre diffs, and certainly, once you've wound a fixed system back to 10%, you get rid of it.

I suspect you know this, but the likes of the Nissan GT-R (and most modern large AWD saloons actually) replace that epicyclic with an active centre diff, which means the car can spend most of the time running as RWD until you want some torque to the front wheels. The simplest systems do so when rear wheel spin is detected. The GT-R one plays all sorts of tunes based on the car's lateral acceleration, yaw rate and steering wheel angle sensors. I believe it's set up to maintain silly drift angles - which is the kind of calibration I simultaneously admire *and* find annoying (the computer drifts it for you!). The Porsche 959 used something similar, but I somehow prefer it. Mainly because I find it bafflingly confusing.

The TT Haldex system is the opposite of the simple RWD, but not as capable because the FWD layout means you can only ever put 50% of the torque to the rear axle (you can't disconnect the front driveshafts). Unless you change the rear diff ratio, or put bigger diameter tyres on the back. :wink:

The Ferrari FF system is the kind of bonkers invention that could only come out of Italy - an additional 2 speed gearbox running off the front of the crank, whose 2 ratios cover slightly different speed ranges to the rear wheel gearbox, giving you a constantly changing torque split until you're at the high end of third gear - when it turns RWD only. It's hilarious.

The thing with any of them though, is that you're always carrying an additional pair of driveshafts and _at least_ one extra differential. Metal weighs a lot, so if you can't break traction, you don't need any of them. F1 swiftly found fatter and stickier tyres, and never needed to look back.


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## Madmax199 (Jun 14, 2015)

Thistlebeeace said:


> The reason is that you generally can't obtain sufficient roll stiffness from just your springs, without sending the axle frequencies sky high. ARBs allow you to increase roll stiffness without having to go higher on axle frequencies - which might not be desirable, depending on what you're trying to achieve. In terms of roll stiffness, they do exactly the same things as springs. 2500Nm/deg of roll stiffness is 2500Nm/deg of roll stiffness, no matter how it's derived. Stiff axles create more lateral load transfer, which reduces grip. Doesn't matter what bits make it stiff.
> 
> The other reason to use ARBs is that you may not be able to achieve the roll stiffness distribution (front:rear) which will give you the handling balance you desire if only relying on the springs. Imagine, say a 1000kg car (sprung mass) with 50% of the weight on the front axle. If you wanted axle frequencies of, say, 1.25Hz front and 1.5Hz rear, your springs would be (using f= 1/2pi x sqrt(k/m)):
> 
> ...


Loving the elaborate answer! I fully understand that it's not always possible to get the desired roll control on springs only without shattering the acceptable ride frequency. The rear of my car is the perfect example of that, I am at the limit of what is usable in terms of Natural Frequencies but need a bar to keep the rear roll control in check. The spring alone could not get the job done.

My issue, and why I'm asking you for your insight, is that I struggle to understand the collective reasoning of the forum about this relationship you've kindly broken down for the discussion. *When well within the range of acceptable ride frequency*, why is it a consensus to go for more bar instead of simply bumping the spring rate to gain the same desired effect while avoiding the negatives of running too much bar? It evades me why the guy with stockish spring rates (which is at the low range of "sporty" ride frequency with the TT) is jacking things by going with super stiff ARBs that should only be fitted on track-bound cars.


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## Thistlebeeace (Oct 15, 2014)

Madmax199 said:


> Loving the elaborate answer! I fully understand that it's not always possible to get the desired roll control on springs only without shattering the acceptable ride frequency. The rear of my car is the perfect example of that, I am at the limit of what is usable in terms of Natural Frequencies but need a bar to keep the rear roll control in check. The spring alone could not get the job done.


No problem, glad it was clear enough!



Madmax199 said:


> My issue, and why I'm asking you for your insight, is that I struggle to understand the collective reasoning of the forum about this relationship you've kindly broken down for the discussion. *When well within the range of acceptable ride frequency*, why is it a consensus to go for more bar instead of simply bumping the spring rate to gain the same desired effect while avoiding the negatives of running too much bar? It evades me why the guy with stockish spring rates (which is at the low range of "sporty" ride frequency with the TT) is jacking things by going with super stiff ARBs that should only be fitted on track-bound cars.


I'm not really sure, but I suspect it might be down to practicality. Depends on the axle design, but sometimes it's much easier to change an ARB than a set of springs - you don't need compressors, and you might not even need to take the wheels off! Don't think that applies with the 8N, but you get the idea. I also think it might be because ARBs are talked about as a finite number of sizes available (rather than by wheel rate), whereas you could spec any spring rate you want - how do you go about choosing that without the above methodology? Less choice is often appealing!

BTW, as I mentioned previously, the negatives of using too much bar are the same as using too much roll stiffness from any part.


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## Madmax199 (Jun 14, 2015)

Thistlebeeace said:


> I'm not really sure, but I suspect it might be down to practicality. Depends on the axle design, but sometimes it's much easier to change an ARB than a set of springs - you don't need compressors, and you might not even need to take the wheels off! Don't think that applies with the 8N, but you get the idea. I also think it might be because ARBs are talked about as a finite number of sizes available (rather than by wheel rate), whereas you could spec any spring rate you want - how do you go about choosing that without the above methodology? Less choice is often appealing!


I thank you for this because to me it made no sense to pass on an infinty spring availability to choose the ARB as the preffered de facto method of increasing roll stiffness. In the 8N for example, you could change all 4 springs on 2 cars in the labor time it takes to remove/replace the front ARB on a single car - therefore this proves that you're correct and it's not pure convenience at play.



Thistlebeeace said:


> BTW, as I mentioned previously, the negatives of using too much bar are the same as using too much roll stiffness from any part.


In terms of roll stiffness, I totally agree with the above comment, there is no difference. However, in practice as the ARB stiffness increases, there is also the negative byproduct of removing independence on the side linked to each other. As a result, the loaded side tend to pull un the lightly loaded side while cornering. This secondary effect called "jacking effect" in racing circles here in the US, induces wheel lift (effect not present with spring bump of the exact same rate).

It can be demonstrated in the pic of the grey TT I posted earlier in the thread - the car was on stock spring rates, but with a stiffer than stock rear bar it became very tripod-prone due to the bar's jacking effect. Same goes for the front too. In real life, the stiffer the front ARB in our car (I firmly believe that the short wheelbase plays a part and accentuate the effect), the harder it gets to put power down from mid-corner-out. The jacking effect of the bar help unload the inner front and reduce that tire's ability to generate grip. For example, without the front bar in a TT, one can apply 100% throttle once the apex is reached... an impossible feat with the stock bar (let alone a stiffer one).

All this to me shows that, in practice, although the ARB help achieve the same thing in terms lateral roll stiffness, it also impedes the car's ability to put power down as the rate of the bar increases due to their intrinsic jacking effect. Thoughts?

*
For those that like to see numbers to visualize things, here is the difference in load placed on each tires while negociating a turn at 1.2G. The only difference is one model has a US-spec R32 15mm rear ARB and the other is fitted with the Euro-spec 19mm R32 bar. The extra jacking effect of the stiffer 19mm rear bar translates into a negative value (tripod with inside rear wheel off the ground), not the best thing if you look to put power down early in the cornering phase*

15mm rear bar









19mm rear bar


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## Grahamstt (Jul 22, 2008)

Fantastic technical input by the guys in the know. 
Although I have been involved in motorsport all my life, designing - building - competing - organising etc. I am old school and have a "seat of the pants" approach, mainly because I am from a rallying background.

Just a pointer to the arb issue. Most cars on this forum are used as road cars and as such it is the "feel" of the car rather than the ultimate performance of the chassis. Not many cars will have been driven at more than 90% of their capability - even on the track.
The handling of the car will inspire more confidence (therefore performance) than the ultimate grip for the amateur driver.
Also, rather than spend a lot of time and money testing, most people will try and follow known decent recommended suspension set ups as a starting point and will probably find that this will match their ability.

My TT has been used for some Road Rally events and you are constantly approaching bends that you haven't had the luxury of driving round previously, so finding a bump/rut/pothole/change of surface mid bend the confidence factor is more important than the ultimate grip theory.

So many different angles to discuss with this topic - maybe needs to go to the new track section?

Keep up the debate guys remembering that theory isn't always the best practice.

Graham


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## NickG (Aug 15, 2013)

Very interesting points well raised Graham!!


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## Von Twinzig (Feb 10, 2014)

Yes indeed Graham. My last track car was driven by Callum Lockie, who after giving it death said the next development of the car would require it to be trailered. I'd pretty much reached the limit for a practical road legal car. And by practical I mean driving it 450 mikes to Le Mans, doing a track day then driving it home.

The car was so stiff that you could jack up one of the front wheels and they would both come off the ground. Still had fully adjustable ARB's (and drop links) both ends....










VT


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## Madmax199 (Jun 14, 2015)

Definitely some interesting points and perspective put forth, keep them coming!


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## Rich196 (Mar 31, 2011)

Von Twinzig said:


> Yes indeed Graham. My last track car was driven by Callum Lockie, who after giving it death said the next development of the car would require it to be trailered. I'd pretty much reached the limit for a practical road legal car. And by practical I mean driving it 450 mikes to Le Mans, doing a track day then driving it home.
> 
> The car was so stiff that you could jack up one of the front wheels and they would both come off the ground. Still had fully adjustable ARB's (and drop links) both ends....
> 
> ...


what was the car?


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## John-H (Jul 13, 2005)

Madmax199 said:


> Thistlebeeace said:
> 
> 
> > ...
> ...


Wise words. I think many people do indeed follow a fashion for ARBs. They also like the lack of roll when cornering and interpret that as better handling but they perhaps rarely push the car to the grip limit and even if they do they do not then fairly compare the result with a softer ARB.

ARBs were originally called sway bars and introduced on large American tourers with soft suspension to stop the car swaying on corners and making the passengers feel seasick. For a performance car they should be considered a tuning adjustment aid, as you say to reduce grip at one end relative to the other slightly as a tweak once the main determinants like spring rate, damping, ride height, geometry etc are set.

A rally enthusiast friend removed his front ARB entirely to gain better turn in and less understeer. Not a fashion follower :wink:


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## NickG (Aug 15, 2013)

I believe UR_TT either has, or has looked at removing the front ARB on his to reduce understeer on the track.

Maybe on the road and with standard suspension settings as you say John, the feel of the car rolling less is actually preferable rather than making time up on a lap?

I'll be honest, it's a new concept to me and really hard to believe the science on it, what throws the mind is the amount of thicker after market ARB's, it's difficult to look past this as they are all being sold as "Upgrades" (Just about got to the stage where by i believe the science now and stiffer ARB's are off of my to do list!)


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## Spandex (Feb 20, 2009)

I think there's a lot of psychology involved in 'performance' mods (big brake kits are an obvious example, where people will imagine their stopping distances have miraculously decreased, but really their brake pedal just has less modulation and has become more grabby and binary in nature). People will imagine or remember how a performance car 'feels' and they become fixated on reproducing the feeling, rather than reproducing the improved performance. This performance feel will be enough to convince them that they have added very real performance benefits to their car and it's unlikely they'll ever have the opportunity to do any reliable testing that proves otherwise - so the myth continues.

Look at the popularity of lowered suspension and large wheels with low profile rubber. There are certainly reasons why these things _might _make a car handle better, if the suspension was originally designed like that, but ultimately what usually happens is people end up driving around in crashy, uncomfortable cars that handle worse than they did before (but crucially 'feel' more sporty).


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## John-H (Jul 13, 2005)

It's a product and there because it sells due to marketing. Think drillings in standard sized brake discs :wink:

I always think of an infinitely stiff ARB going round a bend. Both springs would compress equally and the roll centre would be under the outside tyre as the car tipped and the inner wheel came off the road with 100% of of the cornering forces on the outer tyre.

Now suddenly remove the ARB. The inner wheel would drop back in contact with the road and take a share of the cornering forces. The outside spring would compress as the inside spring extended and the roll centre would move back towards the middle of the car.

That's a simple view because you have front and rear to consider and geometry changes but that's the way I imagine it. I'd rather share the load on two tyres across the axle.


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## Madmax199 (Jun 14, 2015)

John-H said:


> It's a product and there because it sells due to marketing. Think drillings in standard sized brake discs :wink:
> 
> I always think of an infinitely stiff ARB going round a bend. Both springs would compress equally and the roll centre would be under the outside tyre as the car tipped and the inner wheel came off the road with 100% of of the cornering forces on the outer tyre.
> 
> ...


The roll center migration is something that will happen regardless of the ARB rate. It is a factor of load/weight transfer and the suspension's geometric layout (and those are constants). With that said, the way you described it is exactly what the jacking effect does with a front bar in real life.

Whenever that inside wheel gets unloaded while cornering you loose lateral grip overall like you pointed - and on top of that, your ability to put power down early in the cornering phase is considerably diminished (the outside tire is overloaded and the inside tire underloaded). A good example is my car that produces a lot of TQ early, and despite my very wide front tires (315mm), I used to get some inside wheel spin if I get on the throttle too hard and too early after apexing a turn. Without the front bar in the equation, I can deliberately mash the trottle at will once the car is pointed in the direction I want it to go, and all that happens is forward bite and unbelievable exit speed. There is a spec amateur road racing series in the US that is populated by VW golfs (they share our front suspension layout), and I always found it ironic that they all run without a front bar because of the handling advantage, but some people in the forum culture think it must be a handling "upgrade" to run a big front bar on the same suspension design because company X makes and sells it.

I'm happy I sparked a discussion on the topic, maybe a few drones can be freed...


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## Grahamstt (Jul 22, 2008)

As John said, one of my rally cars (Gartrac G3) had compression struts in place of the front arb. 
As the arb would normally have been the fore and aft location of the tca, the compression strut that replaced it was adjustable to increase caster which in itself improved steering response.
The works Escorts used an arb on the rear for forest spec so that it "loosened" the rear end. So not for ultimate grip but to give a particular feel to the handling to enable the car to be set up for the corner.
There are lots of different ways to alter suspension to your own taste, it's knowing what you actually want from your car and how you want it to perform.


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## KarlD (Jul 23, 2015)

Grahamstt said:


> .
> There are lots of different ways to alter suspension to your own taste, it's knowing what you actually want from your car and how you want it to perform.


Well said.

To add to that:

...and knowing how adjusting the various components of the system will help you achieve those desired performance characteristics.


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## Thistlebeeace (Oct 15, 2014)

Madmax199 said:


> Thistlebeeace said:
> 
> 
> > BTW, as I mentioned previously, the negatives of using too much bar are the same as using too much roll stiffness from any part.
> ...


Sorry, has been a busy week. I understand the mental picture that goes with the function of an ARB, adding load to the outside wheel and removing it from the inside. However, it is no different to what happens with springs alone. I'll try to explain why.

Imagine our fictional axle, which has, for argument's sake, that roll stiffness of 2500Nm/deg. We could achieve this in two ways - 1) using springs of 1250Nm/deg and an ARB of 1250Nm/deg, or 2) just springs of 2500Nm/deg. At any given lateral acceleration, the load transfer at the axle by both arrangements 1) and 2) will be _exactly the same_. This means the loads on each of the tyres, inside and out, will be the same. Using arrangement 1 with the ARB *doesn't* cause you to lose load on the inside tyre any more than arrangement 2.

The mental image of using only the springs is that the inside wheel can just keep moving into rebound travel, thereby making inside wheel lift less likely. What practically limits this, is the reduction in wheel travel you will get from having such a high rate at the wheel. A rule when designing and specifying axles is that at maximum rebound, your spring needs to still be compressed by a small amount - say, 10-15mm. If it isn't, then it can actually fall out of the axle! Increasing the rate can significantly reduce the amount of rebound travel you have until the spring becomes completely unloaded (and falls out). Therefore, you would have to change the location of the rebound stop within the damper unit to keep your spring loaded.

Imagine our two arrangements have the following values then:

*Arrangement 1)*
Wheel rate in bump: 50N/mm
Wheel rate in roll: 100N/mm

*Arrangement 2)*
Wheel rate in bump: 50N/mm
Wheel rate in roll: 100N/mm

For both, the static load on the spring is 5000N and note that I have used the same rate for the spring and wheel rates there (i.e. the motion ratio between spring and wheel is 1:1). To calculate how much rebound travel you have before the load on the spring is 0N, and therefore your spring is at risk of falling out, you do:

*(Static load) / (rate)*
Which means:
*Arrangement 1) = 5000N / 50N/mm = 100mm
Arrangement 2) = 5000N / 100N/mm = 50mm*

So in pure rebound travel, #2 can only go to 50mm before the spring is unloaded. In roll, both #1 and #2 are 100N/mm, but if the rebound travel on the inside wheel is 50mm or greater, #2 will either lift its inside wheel (if the rebound stop has been correctly repositioned), or have its spring fall out (yikes).

What this is trying to show is that "Arrangement 2" is no less likely to lift a wheel in roll than "Arrangement 1", for a comparable set of stiffnesses. However, I have to admit to still being a bit hungover from a night at the dogs (I am a rubbish drinker).


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## Madmax199 (Jun 14, 2015)

Hey mate, I am loving the exchange and I think that the community will benefit from it. I am in agreement with pretty much everything you are stating. Computing the numbers have revealed the same conclusion for me as well when I started playing with suspension tuning almost 20 year ago. Heck, I can even produce exact numbers for the TT (through a suspension calculator) that reveals that lateral load transfer and roll control is the same using springs, bars, or a combination of both. What the problem is with all the math and theory is that:

1) they assume perfect conditions (which does not exist in real life).

2) the equations only deal with one condition at a time (lateral or longitudinal motion).

In practice, many things that are not addressed in the lateral load transfer equations (and the effect that ARB vs springs have on the chassis) unfortunately comes into play. Surface is never perfectly smooth and imperfections are constantly transferred when suspension ends are coupled with each other. Furthermore, braking and acceleration causes dive (braking) and squat (acceleration). These natural forces caused by weight being transferred longitudinally are not controlled whatsoever by the ARBs (since they are not lateral forces), the springs and dampers alone assume the responsibility. In the real world, having a car that nose dives, and squats a lot, is equally as bad (in terms of handling and performance) as ones that laterally rolls a lot.

Another thing not possible to include in the math are the specific design constraints. Not really a problem in the front, but the rear of the TT has very limited travel. Dynamic droop motion gets binded considerably by the ARB as result. An easy test that demonstrates this is removing a good-conditioned rear damper by lifting only the corresponding rear wheel, then trying to reconnect it. It becomes a battle due to the bar's jacking effect being very intrusive within the specifics of the design (very limited travel). This negative byproduct of the bars can play a big role in real life. Limiting droop travel through binding induces wheel lift -- and what happens once a wheel leaves the ground (regardless of being provoked by the bar vs the spring)? The rate of the bar becomes an instant zero which is very unsettling to a chassis in the middle of its cornering phase. If the springs are in charge of much of the lateral control, a wheel lift is more manageable. When half (or more) of the lateral control of an axle is relying on the bar and it's effect is gone, anyone can guess what that does to the handling and balance of the car.

Grip and traction (ability to put power down), has also been proven in practice to be reduced when bars are heavily involved. The percentage at which this happens is proportional to the amount of bar involved and the coupling inflicted on the axle. I have seen this firsthand in the late 90's with my track Honda CRX (the first time I was able to monitor data and lateral G-forces). The car generated +0.3 G of lateral force with the front ARB disconnected as a single variable. Puzzled, I repeated the test several time on several surfaces, and the result remained the same. The stock bar simply (through these mentioned real-life intangibles) was chipping away at raw grip generated. Decoupling each end of an axle (restoring suspension independence) always have resulted in the same thing in all the sport/track cars I've been involved with since that CRX (4 Mitsubishi eclipses, two Lancer Evolutions, a professionally raced World Challenge BMW, an SCCA F-prepared Saturn, and now the TT). For example, in the TT my highest recorded lateral G with the factory front ARB was 1.22 G in racing situation. With the same tires size, disconnecting the end links just to test things automatically resulted in a new best (1.37 G recorded via maxQ data), and that was not even in racing conditions which tend to provide higher recorded average and peak lateral forces.

I am saying all this to allow the readers to also understand that besides what works on paper, there is also real life results that, more often than not, adds many variables that can't be added to a rigid computation. Below is a youtube video that I like to link to people to get them an idea as to why many knowledgeable people tend to use as less ARB possible when tuning suspensions. Obviously as we discussed previously, there are practical limits like Natural Frequency putting a ceiling into what's possible with springs alone. But within that limit, and staying specific to the TT platform, ARBs are not necessarily your friend if handling and performance is the goal. Discuss...


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## Thistlebeeace (Oct 15, 2014)

Madmax199 said:


> Hey mate, I am loving the exchange and I think that the community will benefit from it. I am in agreement with pretty much everything you are stating. Computing the numbers have revealed the same conclusion for me as well when I started playing with suspension tuning almost 20 year ago. Heck, I can even produce exact numbers for the TT (through a suspension calculator) that reveals that lateral load transfer and roll control is the same using springs, bars, or a combination of both. What the problem is with all the math and theory is that:
> 
> 1) they assume perfect conditions (which does not exist in real life).
> 
> 2) the equations only deal with one condition at a time (lateral or longitudinal motion).


I've used deliberately simple numbers to explain the phenomena, yes, but the fundamentals still apply once lots of real world noise is applied. It's much easier to understand why that noise does what it does using those fundamentals as a base.



Madmax199 said:


> In practice, many things that are not addressed in the lateral load transfer equations (and the effect that ARB vs springs have on the chassis) unfortunately comes into play. Surface is never perfectly smooth and imperfections are constantly transferred when suspension ends are coupled with each other. Furthermore, braking and acceleration causes dive (braking) and squat (acceleration). These natural forces caused by weight being transferred longitudinally are not controlled whatsoever by the ARBs (since they are not lateral forces), the springs and dampers alone assume the responsibility. In the real world, having a car that nose dives, and squats a lot, is equally as bad (in terms of handling and performance) as ones that laterally rolls a lot.


Yes, you're right - just like it has a roll stiffness (in front view), a car has a pitch stiffness too (in side view), and as you say, the only thing resisting pitching motion under accel/braking is the front and rear springs. Braking retardation can easily match lateral accel in almost any car, so with the same CG height, you could well imagine that the pitching moment is every bit as large as the roll moment - only now you don't have ARBs on your side.

Two things help you out here, however:
1) Wheelbase is generally much longer than track width, so your pitch stiffness is much higher than your roll stiffness (if judged from only the spring rates). 
2) Front anti squat and (especially) rear anti lift amounts are generally quite significant, so you generally get more geometric pitch resistance (from the 'pitch centre') than you do geometric roll resistance (from the 'roll centre').

That's why you can normally get away with 'normal' spring rates in pitch. Be that as it may, yes, you'll always get more pitch stiffness with a stiffer sprung setup. Depending on the car (i.e. how much geometric pitch resistance you have) that might be quite important to overall composure and handling.



Madmax199 said:


> Another thing not possible to include in the math are the specific design constraints. Not really a problem in the front, but the rear of the TT has very limited travel. Dynamic droop motion gets binded considerably by the ARB as result. An easy test that demonstrates this is removing a good-conditioned rear damper by lifting only the corresponding rear wheel, then trying to reconnect it. It becomes a battle due to the bar's jacking effect being very intrusive within the specifics of the design (very limited travel).


It would still be exactly the same if you had a stiff springs/no ARB setup of the same roll stiffness.



Madmax199 said:


> This negative byproduct of the bars can play a big role in real life. Limiting droop travel through binding induces wheel lift -- and what happens once a wheel leaves the ground (regardless of being provoked by the bar vs the spring)? The rate of the bar becomes an instant zero which is very unsettling to a chassis in the middle of its cornering phase. If the springs are in charge of much of the lateral control, a wheel lift is more manageable. When half (or more) of the lateral control of an axle is relying on the bar and it's effect is gone, anyone can guess what that does to the handling and balance of the car.


Again, it doesn't matter if it's via stiff bars or stiff springs - once a wheel lifts at one axle, the stiffness of that axle is no longer causing lateral load transfer at that axle. Any further load transfer after wheel lift occurs at the other end of the car. The behaviour exhibited will be the same.



Madmax199 said:


> Grip and traction (ability to put power down), has also been proven in practice to be reduced when bars are heavily involved. The percentage at which this happens is proportional to the amount of bar involved and the coupling inflicted on the axle. I have seen this firsthand in the late 90's with my track Honda CRX (the first time I was able to monitor data and lateral G-forces). The car generated +0.3 G of lateral force with the front ARB disconnected as a single variable. Puzzled, I repeated the test several time on several surfaces, and the result remained the same. The stock bar simply (through these mentioned real-life intangibles) was chipping away at raw grip generated. Decoupling each end of an axle (restoring suspension independence) always have resulted in the same thing in all the sport/track cars I've been involved with since that CRX (4 Mitsubishi eclipses, two Lancer Evolutions, a professionally raced World Challenge BMW, an SCCA F-prepared Saturn, and now the TT). For example, in the TT my highest recorded lateral G with the factory front ARB was 1.22 G in racing situation. With the same tires size, disconnecting the end links just to test things automatically resulted in a new best (1.37 G recorded via maxQ data), and that was not even in racing conditions which tend to provide higher recorded average and peak lateral forces.


That's great info - and definitely shows how influential (i.e. stiff) ARBs can be on grip balance - doing it in the same session is the best way of generating comparable data. Because each of the experiments involved disconnecting the ARB however, I'm confident that the recorded difference was due to the significant change in roll stiffness (and hence lateral load transfer) at that axle - not due to any difference in the way that springs and ARBs transfer load. It does prove that it's a very, very effective mod that you can do quickly though!

The ideal test would be of the two setups with comparable roll stiffness and roll stiffness distribution, though that of course is a lot more faff and lacks the immediate data capture.



Madmax199 said:


> I am saying all this to allow the readers to also understand that besides what works on paper, there is also real life results that, more often than not, adds many variables that can't be added to a rigid computation. Below is a youtube video that I like to link to people to get them an idea as to why many knowledgeable people tend to use as less ARB possible when tuning suspensions. Obviously as we discussed previously, there are practical limits like Natural Frequency putting a ceiling into what's possible with springs alone. But within that limit, and staying specific to the TT platform, ARBs are not necessarily your friend if handling and performance is the goal. Discuss...


I think the same applies for this guy's experiences too - the comparisons he made were of a car with a) way too much front ARB and b) no front ARB. I don't doubt the result for a second, but again, it isn't comparable. The fundamentals need to be comparable before any additional variables from real life can be properly understood.

Ultimately, I'm not 'pro-ARB' here - just trying to demonstrate that they don't hamper you if specified 'intelligently'. By that, I mean:
- Don't just fit the biggest bars you can find
- Don't use an excess of ARB at one end of the car
- Don't rely just on larger bars if significant increases in roll control are your goal

I'm not about to take the QS on track, but if I did seriously and could find the bits, I'd probably do something like the following:
- Increase springing by approx 50%
- Increase damping by a similar amount (to maintain % critical damping)
- Fit adjustable ARBs at both end, which by calculation allow me to adjust the ARB contribution to roll stiffness by approx -25% to +50% of the originals

And that lot would not just be 'because I'm going on track', but to satisfy (somewhat) these aims:
- Increase roll control significantly (mainly to even out tyre wear across the tread, by reducing camber loss to ground) (springs/ARBs)
- Increase overall body control to better cope with quick changes of direction (springs/dampers)
- Adjust front to rear grip balance by a significant amount (ARBs)

I did pretty much this, for these reasons, with my BMW, and was pretty happy with it. I did spec the springs to shift lateral load transfer 2% rearward as I couldn't achieve this with the adjustable ARBs available. As I touched on in an earlier post, this was mainly to give me the balance I want - UK track days are explicitly *untimed* events (I think for legal/liability reasons) and also, it's still a road car.

In fact, the biggest lever I've found on that car is a set of wheels with a significantly different offset on the front axle. They increase the front track by over 1", which makes the steering feel rubbish but the front end grip seems to never end.

Nick


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## Grahamstt (Jul 22, 2008)

Thistlebeeace said:


> Madmax199 said:
> 
> 
> > Hey mate, I am loving the exchange and I think that the community will benefit from it. I am in agreement with pretty much everything you are stating. Computing the numbers have revealed the same conclusion for me as well when I started playing with suspension tuning almost 20 year ago. Heck, I can even produce exact numbers for the TT (through a suspension calculator) that reveals that lateral load transfer and roll control is the same using springs, bars, or a combination of both. What the problem is with all the math and theory is that:
> ...


I think you two ought to get a room


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## Gonzalo1495 (Oct 13, 2014)

Grahamstt said:


> I think you two ought to get a room


Hey, some actual useful and critical information from two highly knowledgeable people. Lets tell them to gtfo. :?: 
I think a lot of people should be reading this quite frankly but eh. I'm glad this forum is getting more technical and less "he said she said".


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## John-H (Jul 13, 2005)

I'm still thinking about an infinitely stiff ARB with very soft springs. An interesting mental exercise for a hot relaxing bath :wink:


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## Thistlebeeace (Oct 15, 2014)

John-H said:


> I'm still thinking about an infinitely stiff ARB with very soft springs. An interesting mental exercise for a hot relaxing bath :wink:


Ever raced a Tamiya Grasshopper?


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## Von Twinzig (Feb 10, 2014)

Gonzalo1495 said:


> Grahamstt said:
> 
> 
> > I think you two ought to get a room
> ...


+1 [smiley=thumbsup.gif]

VT


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## Gonzalo1495 (Oct 13, 2014)

Madmax199 said:


> There is a spec amateur road racing series in the US that is populated by VW golfs (they share our front suspension layout), and I always found it ironic that they all run without a front bar because of the handling advantage, but some people in the forum culture think it must be a handling "upgrade" to run a big front bar on the same suspension design because company X makes and sells it.
> 
> I'm happy I sparked a discussion on the topic, maybe a few drones can be freed...


Read so many threads on vortex golf section discussing front bar removal I almost contemplated doing it myself. Decided to keep it as it's still not going to see a track anytime soon but you're absolutely right. Great information.

I think that last part is partially attributed to beginners who get caught up in: searches webpage for car upgrades -> these must be all the upgrades I need to have -> which translate to "these are the upgrades you need" posts on the forum. At least that's my theory, the funny thing is many of these companies can do this simply because the average consumer has no idea what they are actually doing to their car or has no real means to test the supposed "effects" it will have on it.


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## FreeRideSkier (Jul 18, 2011)

Anyone interested in making a track car out of a TT, you should check out my blog:










http://audittracecarproject.blogspot.co.uk/

Been there done it..


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## NickG (Aug 15, 2013)

FreeRideSkier said:


> Anyone interested in making a track car out of a TT, you should check out my blog:
> 
> 
> 
> ...


I've dropped you a PM a couple of days ago regarding this mate, with a few questions regarding CSCC.

Cheers 8)


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## Grahamstt (Jul 22, 2008)

Gonzalo1495 said:


> Grahamstt said:
> 
> 
> > I think you two ought to get a room
> ...


It wasn't a criticism twas a tongue in cheek comment cos they are clearly very knowledgeable


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## NickG (Aug 15, 2013)

Grahamstt said:


> Gonzalo1495 said:
> 
> 
> > Grahamstt said:
> ...


 Besides... They already have a room...

http://www.ttforum.co.uk/forum/viewforum.php?f=250

:wink:


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## Madmax199 (Jun 14, 2015)

Hey guys, I hope the exchange between Thistlebeeace and I didn't put you guys to sleep. I am the type that loves to stir the pot and invite people to look at things outside of the status quo. I kept the exchange going for so long because, for one it's not every day that I find people with the technical knowledge to analyze things with me in such depth -- and we are not really disagreeing but rather debating the practical vs theoretical aspects of using springs vs bars to control lateral roll. It is known that even in the racing world there are two school of thoughts when tuning suspension (more springs/less bar, less spring/more bar), and each approach can be made to work. What kept us going is that bringing the theories into real world application (which tend to look at ideal conditions), there are variables and design constraints that are not necessarily under the control of the formulas used to model the dynamics.

My thing is that beside grasping the theoretical aspects of things, I have a put a lot of practical time into specifically tuning the TT platform. My calculations and software shows the same data that Thistlebeeace has brought to the table, and if wasn't for the practice throwing a curve ball at the theories, there would not be a discussion. I hope you guys understand... and to be honest there is always something to gain from this sort of exchange.

So to put an end to this one, we'll say that bars and springs can both be used to keep body roll in check since lateral load transferred through the chassis could care less about what's being used. For the TT, it's design limits, and the less-than-perfect surface conditions in the real world we should conclude that:

1) too much springs will hit the practical ceiling of usable chassis Natural Frequency (let's say 3 Hz)

2) too much bar will have byproducts that are detrimental to overall grip

3) the factory bars (especially the front) are already pushing what's ideal for the platform

4) when having to compromise (not everyone have the means to test and draw their own conclusions), unless you're approaching high Natural Frequencies (again say 3Hz), it's advised to used springs to get better chassis roll control.


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## NickG (Aug 15, 2013)

Not at all, there was a lot of quality information and theories... beats another "Will these wheels fit" thread [smiley=bigcry.gif]

In conclusion, what would run/are you running in terms of spring rates and ARB sizing Front and Rear then? For say perfect track conditions?


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## Gonzalo1495 (Oct 13, 2014)

NickG said:


> Not at all, there was a lot of quality information and theories... beats another "Will these wheels fit" thread [smiley=bigcry.gif]
> 
> In conclusion, what would run/are you running in terms of spring rates and ARB sizing Front and Rear then? For say perfect track conditions?


Pretty sure he runs no ARB in the front and the stock 14mm bar in the rear with the adjusted hole for ideal conditions. I'm curious about the spring rates too however. :wink:


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## Von Twinzig (Feb 10, 2014)

One of the problems I found was getting springs. Once on coilovers the fronts were not too bad, but trying to find short, stiff springs for the rear proved impossible here in the UK.

VT


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## Madmax199 (Jun 14, 2015)

NickG said:


> In conclusion, what would run/are you running in terms of spring rates and ARB sizing Front and Rear then? For say perfect track conditions?


Well, this is a loaded question because what will work on a car with street tires (say factory width), is a world apart from what is ideal for the same car on race tires (especially wide one like I run). And there is no such thing as perfect road or track conditions. A cool experiment is to log the headlight leveling sensors with VCDS, they reveal a lot and can give a lot of insight into how much oscillation the chassis is seing. Below I also linked a video of my rear tire movement during a casual drive on decent road surfaces, it demonstrates how much there is going on even with what would be considered a stiff car.

Video of rear tire movement





I have tried many combinations of spring rates and bar rates over the years in my car. My final setup (with track in mind) is zero front bar with stock rear bar (needed or the springs would make me exceed what is usable in terms of rear Natural Frequency). My spring rate is 800/1300 lbs/in.

However, I must also note that I have more work than the average track TT, and that accounts for a lot with my "ideal" bar/spring selection. For example I run 315mm wide race tires, the front track is 2" wider than stock, I run negative 5 degree of static front camber compensation, the roll center geometry has been altered/raised to compensate for the effect of lowering, my dampers are valved to match the wheel rate, I have aero grip aiding the mechanical grip, my curb weight is 1,100 kg, etc.

With that said, although people tend to assume the car is as stiff as a rock, I till get a healthy dose of body roll when cornering. The car is still moving around when laterally loaded, and the suspension is still working....

Without roll center correction and 15mm US-spec R32 rear bar. Lots of body roll still with 650/1150 lbs/in springs









More recent with roll center corrected and factory 14mm rear bar (800/1300 lbs/in)


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