# Let's talk Suspension/Chassis/Tyre setup!



## Madmax199 (Jun 14, 2015)

I have been meaning to start a thread where we can discuss track setup. This thread can serve as a platform for us track junkies to discuss many topics (regardless of the level of development on the car). Anything you have in mind is fair game, and I think that sharing ideas and comparing notes will be a great way for us to further the knowledge base and help each other reach our goals.

Some topics of interest (thread is not limited to those and anyone can bring topics they want discussed):

- Tyre size/compound optimization
- Alignment 
- Suspension geometry
- Aero
- Balance (weight distribution, steady state terminal behavior, ARB selection, tyre pressure). 
- Chassis stiffening


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## pinotattt (Oct 5, 2007)

Here's my cross weight :!: 1441Kg ex driver


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## NickG (Aug 15, 2013)

Can't wait to get more involved on this thread, still running through the motions of standard alterations at the minute so have nothing valuable to contribute, but it won't be too long!


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## Madmax199 (Jun 14, 2015)

*Tyre size and compound optimization -- part 1*

Let's face it, the TT is not light, has an unfavorable weight distribution, and rely on a front suspension geometry that is far from ideal to make the car turn. What the TT has going for it is some superb traction capability due to AWD. If you are into tracking your TT and/or building it as a track toy, you're doing yourself a disfavor if you're not capitalizing on the car's intrinsic traction advantage.

We all remember the car that put Audi and AWD on the map in the racing world. The infamous Audi 90 IMSA gave Quattro its reputation and now every brand has their own version!!! These beasts were so dominant in the racing world that they got banned from racing because other platforms and manufacturers could not keep up and fairly compete. What is it that gave them such an unfair advantage? Superior traction due to AWD -- if you're going to be heavier due to AWD, it makes no point if you're not taking advantage of the superior traction that it offers at the track. People tend to think that my success tracking a TT and winning all these trophies come from all the modding, or driving ability, my real secret is shoving a lot of rubber under the car.

The unfair advantage of having AWD and superior traction at the track. A must watch as an Audi aficionado an if you track your TT: 





Hans Stuk talking some more about the quattros and their racing advantage:





So, how much rubber were they shoving under these car? Way more than usual so they could put power down at any time while still cornering. The ability to be on the gas earlier than everyone while still outcornering them is the goal. A pic of how much rubber they used on the GTOs:









Now back to the TT. With its weight and poor distribution, how much tyre is ideal for track use? The answer is a lot! I still have not found the limit (and point of diminishing returns) where more rubber don't improve track times. I have tried 275mm, 295mm, and 315mm race slicks and the rule was consistent: wider=faster and easier to drive at the limit. My plans next is to go with 15x12" wheels to support 335mm race tyres. So if my 1130kg TT needs so much rubber, imagine how much a heavier TT is missing out on with 225/235/245 wide tyres at the track -- that's basically carrying a weight penalty for no reason, or carrying a heavy machine gun to war and only using a knife to fight.

So, not everyone has the ability to go swap for 295 rubber and take advantage of that unfair advantage. There always will be compromise due to budget, parts availability, space constrictions, and fabrication skills. I understand that, but that also does not mean running bicycle tires under a front heavy awd car that sees track action. Therefore, how do you get big rubber to fit and be functional under a MK1 TT? The answer is multifold, perfect fitment and how wide you can go is closely tied to how serious you are with using your traction advantage. In part 2 of Tyre size and compound optimization I am going to go into details about how to go about it. Strut perche placement, wheel offset, alignment, spring rates, etc. will be discussed, but I want to give you guys a chance to join the discussion before I go more into it. If you have any specific question or thing you want addressed, feel free to bring it to the table. That's what this thread is about.

PS: Don't think however that the car needs extreme modifications to be able to use big rubber. When I first tracked the TT on stock suspension, I used 315 on 17x10 wheels borrowed from my evo. It was not ideal (rubbed at full lock and awfull poking due to offset), but it worked and allowed the car to trophy in SCCA National events twice.

Stock suspension:










With coilovers and no real body/suspension mods, just proper offset:


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## CollecTTor (Jan 17, 2014)

I'm stuck at this step: bigger wheels and tires. Currently running Bilstein PSS coilovers with OEM Fat Fives and 245/40/17 Dunlop Direzza DZII's with 20mm front/25mm rear spacers. With the added camber I recently added to the front here and adding some spring rate to the rear via modifying the OEM sway bar here, I need more rubber to continue down the path of improved handling. Unfortunately, tires and wheels are a big budget area, so hopefully tax returns will help get me there in February. 8)


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## UR_TT (Nov 8, 2008)

Hi Max,

Been following your thread at vortex for a long time, great read! [smiley=thumbsup.gif]

This thread is something I been waiting/longing for.

My set up as of today,




























"aktuell" is current
"vänster" left
"höger" right
"fram" front
"bak" rear

Front, full alubushes in front and top, total swaybar delete with 120nm springs on two way adj racespec konis. 
Rear, std swaybar and 220nm springs on same racespec konis. (Dampers are rebuilt and shimmed F+B).
245/40-17 on R compound, BBS leMans 17*8,5. (kumho v70a hard)
Haldex "blue"
Power std, chip and exahust.

Current, 
Understeer like a pig. Plans, fix rear toe for a zero or a toe out setup, "push around rather than pushing in"
Slower laptimes last year on 245s compared to 235 the year before. ?!
Can´t find wider wheels for 5*100 than 8,5?! Want to stay on17" for unsprung weight unless bigger is lighter!?

So let the bashing begin!  
Nah, any pointer to me becoming faster is more than welcome, car is driven to and from races but not a daily.

//U


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## Von Twinzig (Feb 10, 2014)

Good thread concept.

In my early days here I asked this exact question.."What's the widest rubber I can run on this thing without rubbing?"

Other than the show car stretch guys there was no clear answer, so, in need of a workable solution I went conservative with the default 225 section.

The rubbing thing is important. Set-ups that work fine on the street or on fast, flat circuits like Silverstone or Snett (apparent clearance inside and outside) get undone on circuits with fast downhill bends like Pouhan at Spa, Paddock Hill at Brands or La Chapelle at Bugatti Le Mans (ask me how I know :? ). My car, like most, has to be driven on the street so needs to be compliant and with no rubber or wheel outside the line of the arch. I accept the compromise this brings, so it will be interesting how this thread develops.

Watching with interest.

VT


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## NickG (Aug 15, 2013)

Team dynamics do pro race 1.2's in 17"x9" in 5x100 fitment, which will run 255/40/r17 tyres nicely. Having seen a few posts recently regarding wheel size, this is how I'm currently being swayed.

What I do know is, my current setup is fine, on 225mm wide tyres using 20mm spacers... So as long as I can find another 10mm these should fit! Hopefully.

Is there a more technical way to be sure of this? Almost definitely, but I couldn't tell you how! :lol:


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## Madmax199 (Jun 14, 2015)

UR_TT said:


> Hi Max,
> 
> Been following your thread at vortex for a long time, great read! [smiley=thumbsup.gif]
> 
> ...


First, let me say that I'm happy that this thread is getting some traction and that you guys are participating. I will do my best to give some inputs where I see fit and hopefully address all that have been posted.

Ok, looking at your setup I see a lot of positives (front arb delete, good dampers, R-comps etc.), but there are a few red flags that need to be adressed before getting a good baseline to gauge future development from.

- IMO, the alignment is jacked up. Fix the alignment and I guarantee it will be a different car at the track. To do this there are quite a few things you need to tackle:

1) your toe is off balanced right/left on both axles. There is no reason for this (especially up front) and should be corrected. A slight front toe out helps with turn-in sharpness, but IMO it is often not worth it for the tyre wear penalty. In the back, you always want to dial some toe-in IMO. Going with zero or some toe out makes the rear too lively on high speed corners and will take away driver confidence. The only time I see zero rear toe or some toe out being applicable to our platforms is with huge effective rear aero that works at all speed generating some substantial downforce.

2) You have way too much rear camber. You are running about double what you should. In the back, the sweet range is between -1.3 deg to about -1.8 deg. More than that and you're under-using the rear patch in the straights and never get into the meat of it while cornering (based on calculated effective stroke range of the rear suspension).

3) You need to figure out a way to dial more static front camber compensation -- or as a susbstitute, dial more caster (dynamic camber gain). These cars start to think about turning at -3.5 deg camber or more. It's the nature of the beast with these strut based front geometry, the dynamic camber loss needs agressive static compensation or you will be understeering. Can't really escape the intrinsic design flaws/limitations unless you start altering the geometry itself (for most, static camber compensation is the easier route to take). For example, I used to run caster plates that allowed me to just need -3.5 deg front camber for good and even temp spread across the front tyres. Nowadays I no longer run them, I have to dial -5 deg of front camber to get the same grip generated and close to even temp spread. So -3.5 (or more) front camber is a necessity with the TT, find a way to get more.

- The other thing I would work on improving is more rubber under the car. This unfortunately requires wider wheels and 5x100 is a pain because there is not much of selection for performance width (9"-up). I suggest converting to a more tuner-friendly bolt pattern like 5x114.3. Such a move will widen your options and open a new world of used wheels availability. Once you have the mechanical support of wide wheels, wider rubber always equals more grip and faster times. I agree with you, 17" is a smarter choice that 18" for track duty.

Besides that, I feel that you are on the right path. The front bar delete is a huge step and removing some of the understeer tendencies of the car, you just need to optimize things around it. One question I have for you is the bushes in the front control arms, you mentioned alu bushes, is that defcon/cookbot style or full solid in the forward position?

PS: isn't it awesome that the TT has such good cross balance from the factory? I know the front/rear distribution isn't the best, but every TT I have seen on the scales have near perfect cross balance.


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## Von Twinzig (Feb 10, 2014)

Ur, what rake are you running? I have 1deg dialled in at the moment. That will help your understeer, but clearly you need to keep an eye on your corner weights. And on that subject, your's is a race car so did you setup your CW with your body weight in the driver's seat?

For the UK track guys (and anyone who wants the best setup) save up and take your car to Chris Franklin at Centre Gravity. http://www.centregravity.co.uk/. Your life will never be the same. Expect to be there 8-12 hours.

VT


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## UR_TT (Nov 8, 2008)

Madmax199 said:


> First, let me say that I'm happy that this thread is getting some *traction*


I see what you did there..  :lol:



Madmax199 said:


> 1) your toe is off balanced right/left on both axles. There is no reason for this (especially up front) and should be corrected. A slight front toe out helps with turn-in sharpness, but IMO it is often not worth it for the tyre wear penalty. In the back, you always want to dial some toe-in IMO. Going with zero or some toe out makes the rear too lively on high speed corners and will take away driver confidence. The only time I see zero rear toe or some toe out being applicable to our platforms is with huge effective rear aero that works at all speed generating some substantial downforce.


Ok Balance toe L/R. My alignment shop will have to be that little more accurate I guess. 
Tyre wear is not an obstacle, if it brings results it´s worth it. I personally don't mind a little twitchy, backend but I hear you.



Madmax199 said:


> 2) You have way too much rear camber. You are running about double what you should. In the back, the sweet range is between -1.3 deg to about -1.8 deg. More than that and you're under-using the rear patch in the straights and never get into the meat of it while cornering (based on calculated effective stroke range of the rear suspension).


Oh, didn´t see this one coming! Just so I fully understand you are recommending less camber than factory specs? (-3,33 to -2,67) 
I did go back and had a look at some pics and you may have a point. 
Red "arrows", there shouldn´t be gap to ground there right? 



















Madmax199 said:


> 3) I used to run caster plates that allowed me to just need -3.5 deg front camber for good and even temp spread across the front tyres.


On this we can totally agree, regulations doesn't allow for rebuilt towers so I need bolt on parts for this fix. Any good links to plates that will hold up for racing? (if in Europe even better)



Madmax199 said:


> - The other thing I would work on improving is more rubber under the car.


If running close to std power, at what level do you think you start losing speed due to too much rubber that cant bee effectively pushed around? Or is that in your opinon a myth?



Madmax199 said:


> One question I have for you is the bushes in the front control arms, you mentioned alu bushes, is that defcon/cookbot style or full solid in the forward position?


They are full solid with needle bearings. 











Madmax199 said:


> PS: isn't it awesome that the TT has such good cross balance from the factory? I know the front/rear distribution isn't the best, but every TT I have seen on the scales have near perfect cross balance.


Maybe, but my posted pic includes a fat driver aswell! (105kgs) So mine isn't that perfect with me out of it ;-)
Thank you for input, I have somethings to ponder on, I will give it a go for spring training and see what results will be. (Will report back of course.)


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## UR_TT (Nov 8, 2008)

Von Twinzig said:


> Ur, what rake are you running? I have 1deg dialled in at the moment. That will help your understeer, but clearly you need to keep an eye on your corner weights. And on that subject, your's is a race car so did you setup your CW with your body weight in the driver's seat?
> VT


Hi VT,

Dont know on rake, I have a regulated min groundclearence of 75mm and at this point front controlarms are the lowest point. 
And you are correct my CW was done with me sitting in the drivers seat. All 105kgs of me..


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## CollecTTor (Jan 17, 2014)

The most/highest OEM spec for rear camber is -2.48° @ 332mm fender arch top to wheel center height. Yes, Max and I agree, ~1.3-1.6° is all you need in the rear. Regardless of power level, more rubber allows more cornering force.


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## Madmax199 (Jun 14, 2015)

UR_TT said:


> Madmax199 said:
> 
> 
> > First, let me say that I'm happy that this thread is getting some *traction*
> ...


1) yeah a little lively backend is good when constitent, predictable and can be induced. When it's randomly looking to bite you, it could be overwhelming even to the best talents, and it shows on the clock.

2) that is correct, your pictures confirm that you're underusing the rear patches. The last pic is the most revealing, the inside rear (under load) is still quite negatively cambered -- the goal with static compensation is to have a perpendicular wheel/ground under lateral load. Therefore some camber compensation is good to account for dynamic camber loss, but too much and you basically have a portion of tyre being effectively used. Shoot for -1.5 in the back (about middle of the ideal usable range) and you should fine.

3) for bolt-on top camber plates, look into Silver Project camber plates. They are based in Poland IIRC, and will get you into the -3 deg as sold (control arm ball joint slots all the way out). If you want more you will have to look into aftermarket tubular control arms, a bit expensive since it's going to be from the US or fabricated. But this will allow you to have all the camber the chassis needs.

As far as when more rubber becomes too much for the available power, I am confident that this is a myth. Whatever is lossed in straight line speed, is more than re-gained just with added lateral grip. On top of that, braking will be improved, and the ability to be hard on the throttle during final cornering stages is exponentially greater. You just need to drive knowing that you can push harder in the corners and apply more throttle earlier at exit, the times will fall in line. Cheers!


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## Madmax199 (Jun 14, 2015)

CollecTTor said:


> The most/highest OEM spec for rear camber is -2.48° @ 332mm fender arch top to wheel center height. Yes, Max and I agree, ~1.3-1.6° is all you need in the rear. Regardless of power level, more rubber allows more cornering force.


Pic for support:


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## NickG (Aug 15, 2013)

NickG said:


> Team dynamics do pro race 1.2's in 17"x9" in 5x100 fitment, which will run 255/40/r17 tyres nicely. Having seen a few posts recently regarding wheel size, this is how I'm currently being swayed.
> 
> What I do know is, my current setup is fine, on 225mm wide tyres using 20mm spacers... So as long as I can find another 10mm these should fit! Hopefully.
> 
> Is there a more technical way to be sure of this? Almost definitely, but I couldn't tell you how! :lol:


So just checking on these wheels, Max you're probably able to help, would the 17x9's fit with a 40mm offset? The 'will they fit' calculator tells me they'd be 15mm closer to the strut than an OEM setup, is there that much room? I'm not too concerned about the arch clearance as they'd be virtually where the OEM wheels are on my 20mm spacers fitted currently anyway!

http://www.willtheyfit.com/index.ph...diameter2=17&wheelwidth2=9&offset2=40#content

Cheers! 8)


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## UR_TT (Nov 8, 2008)

Do a search for ATS DTC, they do 17*9 with a ET30 for 5*100. 
Will be what I´m going for next. [smiley=sweetheart.gif]


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## Madmax199 (Jun 14, 2015)

NickG said:


> NickG said:
> 
> 
> > Team dynamics do pro race 1.2's in 17"x9" in 5x100 fitment, which will run 255/40/r17 tyres nicely. Having seen a few posts recently regarding wheel size, this is how I'm currently being swayed.
> ...


Nick, with that offset you will need to add some spacers to get some inner strut clearance. This is easily done with your generic 5-10mm spacer.


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## NickG (Aug 15, 2013)

Madmax199 said:


> NickG said:
> 
> 
> > NickG said:
> ...


Damn, I really don't want spacers, I know Team Dynamics can be really good with stuff like that, so I might be able to get them made in ET30 if that's the case, just have to investigate the cost of buying direct I guess!


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## Madmax199 (Jun 14, 2015)

What's wrong with spacers? If hub and lugcentric, they're essentially the same thing as getting the wheels with a lower ET.


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## NickG (Aug 15, 2013)

It's only small, but the added weight! If I can get them made correct then surely that's the better option?


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## Madmax199 (Jun 14, 2015)

NickG said:


> It's only small, but the added weight! If I can get them made correct then surely that's the better option?


If the wheels can be the proper offset, that's obviously ideal. But there is no other disadvantage, the spacers are aluminium and add less weight that lowering the offset with the wheels (spacers usually have speed holes to reduce their weight, while wheels are adding full thickness to the center block).


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## Matt B (Apr 8, 2007)

Right max - I'm totally putting my faith in you now. 
I have two very expensive sets of lightweight wheels but they are only 18x8 et 35 with 15f and 20r spacers.
I have kW clubsport suspension with adjustable tie bars, adjustable top mounts and the H&R arbs.
Oh and everything has uprated bushes and defcons and I have the haldex touchmotion

I completely believe you about wide wheels now so I am going to invest probably in 18x9.5 or 18x10 but I am really thinking I will need to make some changes to get these bad boys to fit without rubbing.

So - what would you recommend ? Or is this just a case of finding an ET 40 ish wheel with no spacers and having a bit more poke ? I have to clear my AP racing 6 pots that is my only real consideration.


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## CollecTTor (Jan 17, 2014)

Matt B said:


> Right max - I'm totally putting my faith in you now.
> I have two very expensive sets of lightweight wheels but they are only 18x8 et 35 with 15f and 20r spacers.
> I have kW clubsport suspension with adjustable tie bars, adjustable top mounts and the H&R arbs.
> Oh and everything has uprated bushes and defcons and I have the haldex touchmotion
> ...


The rears have plenty of room for 10" wheels. It's the fronts where you are limited by the strut/spring and fender/wing. Max has gone to Swift springs in a 5" length instead of 6" to raise the perches on his coilovers and make clearance to run the wheels without spacers. My KW coils on my GTI were very slim compared to standard OEM/Koni/Bilstein strut spring perches (huge OD of OEM style springs), TT should be the same. On a buddy's TT with KW v3's, there wasn't enough clearance with a 9.5" wheel but that was with 285 tires. The tire would hit the spring perch, so spacers were needed. The Swift springs would be the solution here as well.


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## Matt B (Apr 8, 2007)

CollecTTor said:


> Matt B said:
> 
> 
> > Right max - I'm totally putting my faith in you now.
> ...


I have kW coils as well so I guess I would be best just to check my clearances. I do like the idea of running 10's. 
Will also see what length my current springs are, if short springs move the platform out of play then that would be a good result - provided I can get the right Spring rate


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## Madmax199 (Jun 14, 2015)

Matt B said:


> CollecTTor said:
> 
> 
> > The rears have plenty of room for 10" wheels. It's the fronts where you are limited by the strut/spring and fender/wing. Max has gone to Swift springs in a 5" length instead of 6" to raise the perches on his coilovers and make clearance to run the wheels without spacers. My KW coils on my GTI were very slim compared to standard OEM/Koni/Bilstein strut spring perches (huge OD of OEM style springs), TT should be the same. On a buddy's TT with KW v3's, there wasn't enough clearance with a 9.5" wheel but that was with 285 tires. The tire would hit the spring perch, so spacers were needed. The Swift springs would be the solution here as well.
> ...


Matt, as Adam pointed shortening the spring length effectively raises the perche height above the wheel/tyre height. This gives more inner clearance, allowing to bring the wheel inward (higher offset). Spring companies like Eibach, H&R, or Swift if you want to get fancy, offer various length/dia/rate springs. Therefore, it's just a matter of ordering the ones you need.


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## Madmax199 (Jun 14, 2015)

Let's talk TT aero! Audi did a pretty good job with the TT in terms of Aero (as a package). The under-belly was designed very conciously for that era, with the front undertray, the 4 wheel kicks/spats (or whatever you want to call them, the two rear trays by the fuel tank. The end result was a decent drag coefficient (0.34) for a car of this shape, and the later recalled spoiler added even less lift at speed.










With that said, for us looking to track the TT, there is room for improvement. Things like lowering the car, front splitter, rear wing or spoiler, rear diffuser, flat-underbelly, fender and quarter panel venting, effective side skirts, improvement on the wheel spats, etc. can have some huge impact on lap times. So let's get a discussion started so we can share notes, ideas, and answer all the questions that may be lurking.

I am starting the convo with this little sim video of the coupe's body. Thoughts?


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## NickG (Aug 15, 2013)

Reminds me, I need to get a splitter made up sooner rather than later (as a replacement for the undertray I don't have!)


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## Von Twinzig (Feb 10, 2014)

Max, totally daft/bonkers thought....is it possible to develop some kind of blown diffuser with our setup?

VT


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## Madmax199 (Jun 14, 2015)

NickG said:


> Reminds me, I need to get a splitter made up sooner rather than later (as a replacement for the undertray I don't have!)


Yeah Nick, do it! I have ran without an undertray for years and cringe at the thought of what that does to the front end at speed. I just built one and it's not that hard with some time, material/hardware, and doing some fabrication to make the mounts structurally sound and chassis-mounted. By itself, it should help reduce a good percentage of the front end lift -- I also plan to add some side wheel spats to decrease the amount of drag from my bulging wheel/tryre.


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## Madmax199 (Jun 14, 2015)

Von Twinzig said:


> Max, totally daft/bonkers thought....is it possible to develop some kind of blown diffuser with our setup?
> 
> VT


Blown diffuser? I am not familiar with the idea!


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## NickG (Aug 15, 2013)

Madmax199 said:


> Von Twinzig said:
> 
> 
> > Max, totally daft/bonkers thought....is it possible to develop some kind of blown diffuser with our setup?
> ...


My knowledge is from F1.

Essentially the exhaust discharges at the start of the rear diffuser, so add to the flow of air and "re-energise" the low pressure air with exhaust gasses (it was used very effectively to increase downforce in F1 and was a primary reason the Red Bulls were awesome for so long!)

It's something I looked at, but decided that the odds of getting it right without any way to test, were very slim and in fact if be more likely to make the car worse! I.e. When off the throttle stability can be effected as you lose downforce, this scared me a bit!


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## NickG (Aug 15, 2013)

Just read into it more, apparently Red Bull minimised the off throttle effect by utilising cold/hot blowing... Essentially throttle stays open at 100% but ignition and fuel is cut, so air keeps flowing through but producing no power - Cold blowing. When Max figures out how to do that on our cars, I'll reconsider a blown diffuser :lol:

They also then changed so thy fuel was added with no ignition stil, fuel would then ignite in the exhaust and hence 'hot blowing' to increase downforce further! Clever stuff, but testing is definitely required!!


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## Madmax199 (Jun 14, 2015)

^^ Yes, just googled it! It looks like open formula technology and very hard to succesfully implement without some serious testing. Get it right and there will be benefits, get it wrong and you'll be shooting yourself in the foot. At my level, I'll take the weight reduction and keep the short-routed piping and dump the exhaust right right in the middle of the car. It would be nice to see one of you guys give it a try though!


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## NickG (Aug 15, 2013)

I'll reconsider when the time comes for the rear diffuser!

I wonder how hard it would be to do a pipe like yours and a standard diffuser then leave a cut out in the diffuser front centre (with a plate fixed over as standard). Then have a "bolt-on" exhaust made up where by you could replace that section trackside with a fabricated section that will reach the diffuser, remove the plate from the diffuser and then test back to back on the same day.

Shouldn't be too difficult to say either yes it works or "F*** me, I need to remove it now before I crash!" :lol:


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## Madmax199 (Jun 14, 2015)

NickG said:


> I'll reconsider when the time comes for the rear diffuser!
> 
> I wonder how hard it would be to do a pipe like yours and a standard diffuser then leave a cut out in the diffuser front centre (with a plate fixed over as standard). Then have a "bolt-on" exhaust made up where by you could replace that section trackside with a fabricated section that will reach the diffuser, remove the plate from the diffuser and then test back to back on the same day.
> 
> Shouldn't be too difficult to say either yes it works or "F*** me, I need to remove it now before I crash!" :lol:


Definitely doable! The problem I foresee is that the effect on a tall production car will not be as pronounced as what is happening on low, flat-paneled, formula cars. Without some tooling, it might be hard to tell if helping or hurting in all conditions.


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## Madmax199 (Jun 14, 2015)

Let's get this thread rolling again!

I finished most of my aero package and it is unreal how much of an effect it has. I must say to everyone considering adding aero to a track TT (or any car), it makes the car drive like a totally different one at speed. When traction limits are exceeded now, instead of backing off to regain traction, you just push more and the car sticks. It is really hard to describe, but starting at 35-40 mph the car suddenly feels heavy (as if someone dropped a tractor trailor on top of it), but the power and ability to accelerate is still there. A 50 mph corner feels like you are doing 20 mph and totaly planted on the ground. I recommend it to anyone, when you see the GT cars flying by you at the track mid-corner and taking the dirty outside lane, now I know why!

The new levels of grip require some attention however. I feel that I could considerably raise my spring rates all around to deal with the new level of cornering grip. You can push so much more that the cornering loads are making, what is otherwise, very stiff springs feel very soft (I have 850/1300 lbs/in on the car font to back). I also feel that I can set up the car way looser to make things more lively and less neutral. I can't get the rear to rotate on throttle-lift no matter how hard I've tried -- so, some rear toe-in must be removed to get the rear more lively on lift (I may even need to dial rear toe out now, that's how glued the rear feels).

The mounts I had for the splitter also needed some revision. I made sure at the fabrication stage that my mounts (center posts and rear mounts) were all structural and chassis-mounted). What I didn't realize is that the bulk of the forces at play are acting in a localized manner on the front overhang. I did 4 bracing struts and thought it would be enough, but I underestimated how much load was placed on them. After my fisrt little testing round, the two central support rods failed. The bolt holes twisted, and the bolts gave in. I then added better hardware and load washers at the top as well, they still took a beating and I had to double the washers on both side to prevent them from buckling. I think that I now have the formula to secure the splitter, but will add another central strut to spread the frontal load and make the overhang stronger. Functional aero on a track car is some serious stuff!!!


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## CollecTTor (Jan 17, 2014)

Awesome to hear you so impressed with the improvement, congrats!


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## NickG (Aug 15, 2013)

Love me some Aero, as you know, it should be one of the last things done, so i'm a way off that for now!

Looking awesome though and i'm glad it works well too!


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## Converted2VW (Feb 13, 2011)

Hello everyone!
Track junkie in Texas here, although I control my addiction by driving my 2001 Roadster in the streets too...

Question: What are you guys using for coilover suspension?

I'm using ST coils but have found there's lots of body roll on corners which I'd like to get rid off.
These are great for street / spirited driving but I feel they fall short on the track.

I've been chatting with fellow TT trackers on the web and have heard H&R ultralows are a great option. Any other options out there? I'm looking for a stiff set up I can push further with confidence.


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## Converted2VW (Feb 13, 2011)

For the sake of completeness, these are the options I've been looking into:

1. H&R Ultra-Low or RSS coilovers (don't think RSS are available for the TT mk1)
2. Bilstein PSS9 adjustable
3. KSport Kontrol pro adjustable CAU051-KP

What others are you using and do you see body roll?
Alternatively, is it possible to get stiffer springs? although dampening is still affected by shocks...


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## NickG (Aug 15, 2013)

I don't know if they're available in the states, but I use GAZ Golds to great effect. Specified Spring rates that are higher than most kits (although not quite Madmax level!), with valving to suit that!


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## Madmax199 (Jun 14, 2015)

Converted2VW said:


> For the sake of completeness, these are the options I've been looking into:
> 
> 1. H&R Ultra-Low or RSS coilovers (don't think RSS are available for the TT mk1)
> 2. Bilstein PSS9 adjustable
> ...


Forget option 3 and the Ultra low crap.

H&R RSS clubsport is the ticket! That's what I run but with custom revalve and spring rate, but make no mistake they are more than capable right out of the box. All things considered, best track coilover for the platform (they are listed for the mk4 R32 but fits the TT as they're esssentially the same suspension wise).

Your other option would be to get the PSS/PSS9 (same thing except for the pointless bleeder screw) and have those revalve for stiffer spring rates since they're dialed soft for street use. If I was to do it again, I would have used a set of PSS (same dampers as the RSS clubsports btw) and revalved them. This would have given me the same thing a saved a few hundreds.

Get the RSS and you will never use the term "body roll" in a long time!


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## Converted2VW (Feb 13, 2011)

Madmax199 said:


> Converted2VW said:
> 
> 
> > For the sake of completeness, these are the options I've been looking into:
> ...


Thanks for the input Max. That's the direction I was leaning...

Now, tell me more about revalving...are we talking about increasing internal strut pressure to stiffen damping as well as increasing spring rates?
Who does that kind of work?


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## Converted2VW (Feb 13, 2011)

Also, if revalving and changing springs, wouldn't it attain the same result to do this with any good coils?


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## Madmax199 (Jun 14, 2015)

Converted2VW said:


> Madmax199 said:
> 
> 
> > Converted2VW said:
> ...


Yes, revalving entails changing the rebound and compression curve characteristics in relation to a known force. It is done by manipulating the size/quantity of the oil bypass plates. Any good road racing shop does this, but you can also go to the source. Bilstein California offers the service for all their dampers (even when sold in an off-brand kit like H&R). I believe the price is about $125 a piece for full service and revalve (including dyno plot).


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## Madmax199 (Jun 14, 2015)

Converted2VW said:


> Also, if revalving and changing springs, wouldn't it attain the same result to do this with any good coils?


Yes, but not all coilovers are easily revalved. Bilstein, Koni, GAZ, AST -- Yes! Things like KW and others you will be left with your pants down looking for revalve services. That's why I tell people, if you're going to upgrade springs and revalve the dampers, start with the PSS. At the end you end up with the same thing as a revalved RSS Clubsports but for a less (they're based on the same dampers). :wink:


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## UR_TT (Nov 8, 2008)

>Max,

I went on and did this today, (rear 14mm std)


















Do you run adj droplinks for this to work properly or are you still on std ones?

//U


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## Madmax199 (Jun 14, 2015)

I am still on standard ones. They are fine for using this mod, a slight radial rotation of the bar put them at zero preload with no binding at rest. Reminds me that I have these to install, project for tomorrow!


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## UR_TT (Nov 8, 2008)

8) 
Just wet myself!

Can´t go on post porn like that without a warning!

 :twisted:

//U


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## Converted2VW (Feb 13, 2011)

Madmax199 said:


> Converted2VW said:
> 
> 
> > Also, if revalving and changing springs, wouldn't it attain the same result to do this with any good coils?
> ...


Thanks Max!

After your first message I emailed ST to check on revalving options...I'm not expecting an answer.

For $1600 the RSS seem like the better option right out of the box...
I did try to find a used set of PSS9 but no luck.

Luis


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## kane (Jul 26, 2010)

Converted2VW said:


> I did try to find a used set of PSS9 but no luck.
> 
> Luis


If you're still looking


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## Antthony (Jul 29, 2016)

Max (or anyone who can answer), regarding this illustration:










Not meaning to ask silly questions here, just trying to understand what this picture is trying to illustrate  
Does 'Sports suspension' refer to the S Line suspension, or is this some how referring to aftermarket suspension?
Obviously as the standard suspension isn't height adjustable, the details given for 'standard suspension' refer to if fitted with lowered coils?

And those camber values, I take it those are what you will have at the given ride height? 
May I ask also, how much camber can we get in the front and rear with say a set of coilovers and around 25mm lowered?

Thanks


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## Antthony (Jul 29, 2016)

I guess nobody knows  :lol:


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## CollecTTor (Jan 17, 2014)

Us American's don't pay any attention to OEM suspension package, at least compared to how much you UK guys focus on it. That said, those ranges aren't the end all be all of rear camber settings. Look at the huge jump in camber on standard suspension from 355 to 360mm heights. It's a half degree, same change as the same height changes on the sports suspension and very similar overall numbers. That said, the more camber you have in the rear, the more your toe will be out of spec. Anything over -2* will give accelerated rear tire wear. On OEM sports suspension on my 180Q, I had -2.8* on one side and -3.1* on the other due to the springs sagging over the years. This caused the excessive camber, and resulted in accelerated inner tire wear. So even on OEM suspension, I needed one pair of adjustable rear lateral links (they're not really control arms). You want to shoot for ~-1.5* (between -1.7* and -1.3*) in the rear regardless of height to maintain optimum handling and minimize tire wear.


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## Antthony (Jul 29, 2016)

Yes that is all basically generic rear end info for any modern AWD, but I was wondering the origin or details of that diagram as i've asked about it on a few threads now with no answers. But nobody knows so I won't bother with it anymore 

What is meant by _"Us American's don't pay any attention to OEM suspension package, at least compared to how much you UK guys focus on it. "_? You have me intrigued.

I've also asked here and on a few of the Facebook pages about how much static camber can generally be had in the front to no avail, so I guess i'll just have to find out 

Cheers.


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## CollecTTor (Jan 17, 2014)

As for origins, that diagram is OEM, so not sure what you are interested in. What is meant by the "Us Americans" statement is that the UK community seems needlessly obsessed with pre and post facelift ride heights, when at the end of the day, the height makes no difference and the soft stock springs aren't going to handle that great regardless of height or sports or not or pre or post facelift.

As for static front camber, depends what "generally" means. You can get close to -2° by sliding the ball joints all the way out. You can get close to -3° by adding eccentric top mounts. You can get close to -4° by using Mk2 ball joints in addition to above. And you can make control arm extenders to get to.-5°.


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## Antthony (Jul 29, 2016)

CollecTTor said:


> As for origins, that diagram is OEM, so not sure what you are interested in. What is meant by the "Us Americans" statement is that the UK community seems needlessly obsessed with pre and post facelift ride heights, when at the end of the day, the height makes no difference and the soft stock springs aren't going to handle that great regardless of height or sports or not or pre or post facelift.
> 
> As for static front camber, depends what "generally" means. You can get close to -2° by sliding the ball joints all the way out. You can get close to -3° by adding eccentric top mounts. You can get close to -4° by using Mk2 ball joints in addition to above. And you can make control arm extenders to get to.-5°.


Thanks for that, very interesting, and makes sense to me also. By generally I just meant with the standard components what is the normally achieved maximum, so I know where my starting point is essentially, and you answered that as -2° thanks.

By eccentric top mounts do you just mean these things?:


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## CollecTTor (Jan 17, 2014)

Antthony said:


> By eccentric top mounts do you just mean these things?:


Sorry for the late reply, but yes, the SPC strut mounts. They are what I have on both my cars.


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## Antthony (Jul 29, 2016)

CollecTTor said:


> Antthony said:
> 
> 
> > By eccentric top mounts do you just mean these things?:
> ...


No worries, thanks. By the way, those ones I showed above are quite simple, supposedly give 1 degree neg camber and 1 degree more caster. To be honest that combined with sliding the ball joints like you suggested should be more than enough for my application as I really can't see me running more than 2.5 degrees neg on the front on this car. So would those simple ones be fine for that?

Cheers.


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## CollecTTor (Jan 17, 2014)

Antthony said:


> CollecTTor said:
> 
> 
> > Antthony said:
> ...


Like I said, they are what I use, and I'm just under -3* per side currently. [smiley=cheers.gif]


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## Gonzalo1495 (Oct 13, 2014)

Rather than open up a new thread, I figured this best questions belongs in here.

It's rather obvious the front of the car needs major tweaking. One of the concerns I have for my personal car is the Front ARB.

At what point can you get rid of the front arb? Can the delete be done to even a bone stock TT, or does it need much stiffer suspension to compensate first?


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## Antthony (Jul 29, 2016)

Start with Cookbots and firmer bushes, and the camber adjustability. Touch the ARB last if at all.


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## FJ1000 (Nov 21, 2015)

So coilovers ordered for the TT, and I'm wondering what's an optimal ride height for track driving?

Has anyone experimented with ride height and found what works well?

Measurements from ground or hub/wheel centre to arch would be handy.

Thanks!

Sent from my iPhone using Tapatalk


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## 1781cc (Jan 25, 2015)

I just set mine as low as I could go without rubbing... I am having her counterweighted and setup properly in June so will be interested to see what the setup will be after that.


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