# Strut float gap + new pics



## John-H (Jul 13, 2005)

Here's a question. Does anybody know what the gap is for? Specifically, the gap between the strut top retaining washer and the body mounting point? It's about 9mm or so on the TT depending on the condition of the top doughnut mount under the wing.

You get it on the TT and many other cars with McPherson strut type suspension. If you jack the wheel off the ground the gap closes up and the strut hangs on this top washer - it's the only thing that stops the strut falling out of the bodywork. Much older cars used to have rigid rubber mounts with no float.










I've been getting banging as the washer hits the bodywork when I go over speedbumps. I've just fitted some additional 9mm thick washers, to fill the gap, made from Powerflex material. Initial testing seems to show the banging is no more but I haven't tested it on a big speed bump yet.


















I just wanted to be sure I'm not compromising any other design feature by doing this and wondered if anyone could answer the question of what the float gap was actually for?









.


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## JAAYDE (Aug 15, 2006)

Interesting stuff John, i had my top mounts changed about 8k ago but i'm sure i still have a gap :?

Think i will take a look tomorrow (later today even) and report back..

ps you should give the engine bay a little clean :wink:


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## KenTT (Feb 20, 2005)

Hi John

You got me think about this, I wasn't sure that there was any float as such, just a certain amount of flex within the top rubber mounts.

I have gone and had a look at mine. The gap does not look as big as the gap on yours, it measures 7mm to the bottom of the rubber covered disk.


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## John-H (Jul 13, 2005)

Hi Jae,

I hang my head in shame and promise to clean my bay  . That picture was taken after a lot of bad weather. At least it shows up clean where the rubber was hitting the bodywork :wink:

Hi Ken,

Very nice pictures showing your gap very clearly (and clean engine bay :lol: ). Mine are new mounts which had an even smaller gap when first fitted but the Koni coilovers and 2,000 miles driving round Scotland opened it up again - to say nothing of the effect from Speedbumps.

I just can't think why the modern designs of strut top mount have this gap. There must be some reason for it.

My RS2000 has a similar gap but there is much more rubber (extended up from the doughnut) to absorb the impact of the top retaining washer. The TT only has a thin rubber edge on the washer.

Uprated adjustable mounts from K-MAC don't have this gap and the piston rod is rigidly retained in a poly joint. So I presume there's no harm in holding it more rigid.


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## Black Knight (Jan 16, 2007)

I've installed the KMAC strut tops on a calibra and there was no extra noise or vibration. I couldn't tell the difference really until I altered wheel alignment which is why I installed them.
I can't really think of a reason to have the strut top looser in any circumstances as it will obviously compromise roadholding and make wheel geometry unstable. The strut will absorb bumps and vibrations, unlike wishbones for example which do need a rubber "cushion".

IMO the only reason at all why struts tops are suspended in rubber and not rigid is the fact that struts increase their angle relative to the chassis/ground when the suspension compresses and decrease as the suspension extends.
This angle change is not that great obviously so the rubber slack is enough to accomodate it, otherwise they'd need to use a ball joint at the top too. Come to think of it, I wonder why they don't use one? Probably because it is easier for a bearing to supper the load, even though I know there are load bearing ball joints?


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## John-H (Jul 13, 2005)

Yes I can understand why it's suspended in rubber because the angle of the piston rod will change as the suspension compresses (and it absorbs vibration) but why the free play float gap?

If you jack the car up you can actually rattle the strut top up and down if you grab the wheel and lift! This is just uncontrolled slack! Beats me why :?


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## cyberdude (May 24, 2002)

I'm surprised no one else with similar set ups have complained about the knocking problems you're experiencing John. Makes me think that they are just living with it (which I find difficult to believe) or there is something not right with your set up.

You say you haven't lowered the car. Have you tried lowering it 25-30mm to see if the knocking persists?


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## Black Knight (Jan 16, 2007)

Dunno, on most of my other cars it looked something like this:










And there's nothing that can bang there..

Even though the 6-7mm gap TT has should be enough, the strut shouldn't move out of rest position by more than that IMO.

But, TBH when I first saw the TT strut tops I thought there was something wrong with them to look like that..
Maybe I'll put some dye or something on my chassis under the strut top to see if the strut top touches is?


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## timvgti (Mar 14, 2007)

I have the 'gap' also!
I never heard any knocking sound (happily).
I have a KW Sport Suspension Kit.
I think there is nothing wrong, this is just the way it's meant 2 be?

My 'gap':


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## TTCool (Feb 7, 2005)

John-H said:


> I've been getting banging as the washer hits the bodywork when I go over speedbumps. I've just fitted some additional 9mm thick washers, to fill the gap, made from Powerflex material. Initial testing seems to show the banging is no more but I haven't tested it on a big speed bump yet.
> 
> .


Hi John

Looks like this could be a Demon Tweek  :wink:

You do realise you will now have to attend the NW cruise :roll:

Regards

Joe


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## TTCool (Feb 7, 2005)

PS I see you have 

Joe


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## CHADTT (Jun 20, 2007)

Probably two uniformed questions below.!!

Does it really matter if there is a gap unless the car goes airbourne?

Is the gap there to allow for some form of heat expansion?


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## Black Knight (Jan 16, 2007)

What kinda troubles me more is side to side movement of the strut. The center shaft seems quite thick and quite near the encompasing hole of the chassis. The strut moves and tilts around in the mount. On my old calibra with standard strut mounts the struts would move around 10mm in each direction when you turn the steering wheel lock to lock. And calibras struts are a lot more vertical than TTs which are leaned inwards and backwards(castor) and should try to tilt and move around even more.


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## John-H (Jul 13, 2005)

cyberdude said:


> I'm surprised no one else with similar set ups have complained about the knocking problems you're experiencing John. Makes me think that they are just living with it (which I find difficult to believe) or there is something not right with your set up.
> 
> You say you haven't lowered the car. Have you tried lowering it 25-30mm to see if the knocking persists?


This is a very relevant point. I've not lowered the car and I've stuck to the original ride height because I don't want to loose ground clearance. This means that the piston rods are more extended out of the strut body than someone who has lowered.

When you couple this with the fact that the piston travel is less than standard with the Konis (to allow for lowering), then you can see that the pistons are going to more easily become fully extended when going airbourne and the top washers hit the body as the wheels leave the ground.



CHADTT said:


> Probably two uniformed questions below.!!
> 
> Does it really matter if there is a gap unless the car goes airbourne?
> 
> Is the gap there to allow for some form of heat expansion?


Not uninformed at all! This is only a problem when the wheels leave the ground and the struts hang.

I think the effect is there with standard suspension but you'd have to hit the speed bumps faster and harder to make the car bounce high enough to get the problem - so you don't experience it because you don't drive over them that fast.

I can't see anything expanding as much as the quite considerable gap though.


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## cyberdude (May 24, 2002)

John-H said:


> When you couple this with the fact that the piston travel is less than standard with the Konis (to allow for lowering), then you can see that the pistons are going to more easily become fully extended when going airbourne and the top washers hit the body as the wheels leave the ground.


Is it not possible that by not lowering, you are running the Konis outside their design envelope, i.e. the 'natural at rest position' is not within the intended design envelope. May be worth checking with Koni on this. :?


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## John-H (Jul 13, 2005)

cyberdude said:


> John-H said:
> 
> 
> > When you couple this with the fact that the piston travel is less than standard with the Konis (to allow for lowering), then you can see that the pistons are going to more easily become fully extended when going airbourne and the top washers hit the body as the wheels leave the ground.
> ...


Koni say that standard ride height is perfectly acceptable - well they did over the phone. They are supposed to be adjustable which I would take to mean to encompass a variety of ride heights. You have a point though - clearly it's not just the rest height that varies but also the allowable travel above and below the chosen rest point - as one increases the other must reduce. The total travel remains the same.


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## Black Knight (Jan 16, 2007)

I think shocks provide same resistance over their entire length.

IMO the main reason for fitting different shocks when you lower a car significantly is that the standard shocks still provide same resistance per mm of suspension travel. And since you've lowered the car with different spring you've reduced the travel, the amplitude of the springs, so the shock provides less total resistance per one bounce/jounce. Then you put on firmer shocks and you get back to the same or more resistance per bounce/jounce as was on standard.


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## John-H (Jul 13, 2005)

Black Knight said:


> I think shocks provide same resistance over their entire length.
> 
> IMO the main reason for fitting different shocks when you lower a car significantly is that the standard shocks still provide same resistance per mm of suspension travel. And since you've lowered the car with different spring you've reduced the travel, the amplitude of the springs, so the shock provides less total resistance per one bounce/jounce. Then you put on firmer shocks and you get back to the same or more resistance per bounce/jounce as was on standard.


Yes dampers are the same damper rate no matter where the ride height is set - at least all the ones I know - ignoring active types with the potential to adjust dynamically or ones that vary damping with frequency etc.

The Koni Coilovers have a separate adjustable rebound damper setting however. The ride height is set by adjustment of the lower spring platform retainer position. The springs stay the same length and rate but obviously the car centre of gravity lowers so the roll is reduced which in this respect is like increasing the spring rate. Rebound damping can be set separately to match.


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## Black Knight (Jan 16, 2007)

John-H said:


> Black Knight said:
> 
> 
> > I think shocks provide same resistance over their entire length.
> ...


Actually, no, CG lowers compared to the ground which is really irrelevant when it comes to body roll. Lowering a car with macpherson suspension lowers its roll center(relative to the CG) and this actually increases body roll - gives the CG more leverage to roll the car around the roll center.


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## John-H (Jul 13, 2005)

Black Knight said:


> John-H said:
> 
> 
> > Black Knight said:
> ...


Well I wasn't going to mention roll centres but although that's true for independant McPherson struts, it's more complicated than that because of the anti roll bar. If the roll bar was infinitely stiff for example, the roll centre would be at the contact point of the outside tyre and the road and the body would only roll by lifting the inside wheel off the ground. Lowering the car would then reduce the vertical distance between the centre of gravity and the roll centre and reduce weight transfer. The real picture is a cross between the two. The Konis also have progressive rate springs so the roll stiffness varies with roll, further complicating matters - and this isn't considering the rear suspension which is a trailing arm design where roll centre tends to be at ground, so again lowering the centre of gravity would reduce the vertical moment between it and the roll centre. It has a roll bar too. Overall, lowering reduces roll but will affect front and rear to a differing extent. It's a complicated compromise. I'd like to work this all out properly with a computer animation perhaps.

Anyway, I spoke to a motor engineers, Roscoe Engineering in Liverpool, about the top bush. Their comments were that many MOT testers don't like the float gap, as when the car is jacked up and they heave on the wheel, there is a very disconcerting looseness in the whole assembly. The manufacturers say it's fine when the car is resting on the ground. Of course there is a problem when it isn't! The reason for the gap they say is just to allow for articulation with steering and compression - the whole thing is effectively like a ball joint.

They were interested in the modification, as they deal in rally sport and know of this problem. Their only caution was that if it was tight it might strain the top retaining washer and bend the end of the piston rod. It isn't tight though, as I can turn the washers by hand when assembled, so they are still free to move. They thought that was probably OK but advised checking for play at all steering angles - which I've done. The only thing that bothers me is that when dirt gets in there the washer may tend to rub off the paint from the body mount as they are in contact.

So in the mean time I will remove the original rubber edge to the top washer which will leave a 3mm gap and allow the Powerflex washers to rattle.

What I think I might do longer term is to make a second thinner pair of washers with a tigter centre hole that jams in place on the top washer, so ensuring a 2 or 3 mm or so gap and which keeps it suspended above the paintwork.


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## Black Knight (Jan 16, 2007)

So any change of the top end of the strut hitting the chassis with side-to-side movement?


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## John-H (Jul 13, 2005)

Black Knight said:


> So any change of the top end of the strut hitting the chassis with side-to-side movement?


If you take a cross section through the standard doughnut and exaggerate the movement it's a bit like this:










That really is exaggerated though.


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## Black Knight (Jan 16, 2007)

That's not really what I thought.
The center shaft is thick as the hole in that mount cutout you just posted and it is quite near the edge of the mount hole in the chassis. At least it looks that way on the pics someone posted.
Is it possible that the shaft/rod moves sideways enough to touch the chassis?
I think the strut does experience forces that will make it move around in the mount. Simple suspension movement causes it to tilt in the mount as the suspension travels. But braking, acceleration and lateral forces would make it want to move sideways, or in other words the strut would want to rotate around the bottom ball joint.


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## John-H (Jul 13, 2005)

I sadly have to report that although my modification has helped reduce the banging I was experiencing it has not eliminated it.

I've got a wide platform speedbump under a zebra crossing I use as reference on the way to work. I can drive over this a little faster before noticing some knocking and the knocking is not as extreme but it is still there.

I suppose I'm feeling the sudden change of compression rate between the original rubber mount and the Powerflex washer 

Whilst I was playing around with the rubber edging to the top washer the other day I noticed that the amount of distortion in the top mount is quite extreme. Not only has it distorted upwards - it's also distorted sideways towards the middle of the car!

Perhaps I hit speedbumps too fast. Perhaps I need the adjustable mounts in order to control camber which has clearly changed


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## Black Knight (Jan 16, 2007)

Are you sure the strut rod/piston isn't touching/banging the chassis with sideways movement? It seems quite possible, even more possible to me than the strut top touching the chassis.


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## HighTT (Feb 14, 2004)

John-H said:


> I've got a wide platform speedbump under a zebra crossing I use as reference on the way to work. I can drive over this a little faster before noticing some knocking and the knocking is not as extreme but it is still there.
> 
> Perhaps I hit speedbumps too fast.


Slightly off topic but if you hit speedbumps at an angle ( on-coming traffic allowing :roll: ) you will find that the whole experience is much less jarring


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## John-H (Jul 13, 2005)

Black Knight said:


> Are you sure the strut rod/piston isn't touching/banging the chassis with sideways movement? It seems quite possible, even more possible to me than the strut top touching the chassis.


Does this help clarify (thanks to ken's image). There is a chance the dished retaining washer might touch the body but there is no chipped paint.


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## Black Knight (Jan 16, 2007)

And you're sure the washer is hitting the body with up-down movement? Or do you just think due to the fact you can move the strut up/down when the car is lifted you can hear that happening when driving?
Have you tried putting some kind of dye or whatever on the body all around the mount hole to see if the washer would get dyed?

I can't really see the reason for the gap though. If I got this straight, the only thing retaining the strut from falling out is the top washer(red) dropping onto the chassis(the gap)? Why on earth is there a gap there then? 
Obviously the car would have to literaly jump into the air for the strut to start actually pulling the retaining washer down with its weight and this should hardly ever happen, but still there is no reason why there should be a gap before the retaining washer hits the chassis? 
Perhaps because if it was sitting flat on the chassis the strut tilting would cause the retaining washer to tilt against the chassis? And when it moved sideways the washer would slide across the chassis. This would not be such of a problem if there was a rubber bushing/washer between obviously.. but the strut movement would still try and distort this bushing and it might not last that long?


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## John-H (Jul 13, 2005)

Yes it does hit the body as you can see in this picture where the dirt has been rubbed off and the top of the body mount is clean  .

It does it more than you think and as I say speedbumps are the worst at doing it.

But yes, it could in addition be something else contributing to the vibration.


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## stevey4 (Mar 21, 2005)

Hi ya,

I have exactly the same gap with nicely polished metalwork under the rubber mount where it touchs over bumps. I also have an annouying knocking as i go over small jerky bumps.

I reached under the wheel arch, grabbed hold of the spring and pulled it towards me and away a few times quite hard and I could hear a faint knocking the same as I hear while driving. Next step for me is to get a pro opinion re this.

Steve.


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## TTCool (Feb 7, 2005)

Sorry to hear this John. I'm just mulling over random thoughts here. Could it be something to do with your TT being a 1999 ( I'm guessing ) model and something changed in the mounting area, in the body panel pressing for example, very shortly after that; unlikely I know. Mine is May 2000 and I have no problem with the Koni Sport Dampers and Eibach Pro Springs along with a 25mm drop. Your kit is the coilover version which suggests to me to be where the problem is, in the kit itself, _if there is a problem._ I'm assuming you didn't have this problem before. The only thing that has changed is the fitting of the koni Coilovers. The more adjustment possibilities you are afforded the more chance of wrong footing the car. Do you think that if my setup was on your car you would still have the same problem? Have you thought of softening the dampers? :roll: I would stand back from a purely technical stance and approach the problem with a huge amount of common sense. One lesson I learned when I was racing was 'It shouldn't work, but it does' 8) or conversely, 'It should work, but it doesn't' 

There must other members on here who have your setup. Has anyone experienced this? Does the bang occur only on speed bumps? Have you tried the airborne test? I can't help feeling that some of the problem is in Koni's chosen parameters with regard to damper firmness, spring rate and rebound with regard to this specific application, the TT. The coilover kit, so far as I know, is more leaning towards track use where there are no speed bumps :roll: Also, I used to find that it was very easy to overdo my enthusiasm for arriving at the best possible handling etc on my road cars. In my experience once you choose a more competition orientated route you often find yourself between a rock and a hard place and your supplier of components can only generalise in what they provide for your use in your particular application, which in this case is trying to satisfy track and road use. I've got my firmness adjustment as stiff as it will allow without spoiling the ride, so not at maximum.

Tommy: "Doctor, when I raise my arm, it hurts"
Doctor: "Don't raise your arm"

Tommy: "I think I'm shortsighted "
Optician: "Come over to the window. What can you see?"
Tommy: "I can see the sun"
Optician: "How far do you want to see"

Joe


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## Black Knight (Jan 16, 2007)

John-H said:


> Yes it does hit the body as you can see in this picture where the dirt has been rubbed off and the top of the body mount is clean  .
> 
> It does it more than you think and as I say speedbumps are the worst at doing it.
> 
> But yes, it could in addition be something else contributing to the vibration.


It also looks to me like the body mount is clean a bit on the side? As if the mount top both tilted and dropped down on the body mount?


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## John-H (Jul 13, 2005)

Black Knight said:


> ... It also looks to me like the body mount is clean a bit on the side? As if the mount top both tilted and dropped down on the body mount?


Possibly - but it might just be that my hand rubbed off some of the dirt as I was screwing off and on the plastic cap :wink: .



HighTT said:


> ... Slightly off topic but if you hit speedbumps at an angle ( on-coming traffic allowing :roll: ) you will find that the whole experience is much less jarring


Hi Ian,

Very true but I think the suspension should be capable of handling things like this - which is my test speedbump:










It's outside the Manchester United football ground if anyone wants to try it. The platform is quite large and exactly the height of the curb. OK the car does bounce a bit at 30mph but why should I put up with a bang with my TT when my old Escort handles it without complaint. In fact the only thing I remember with the original TT suspension was a creaking ARB which I've now fixed.

Joe,

Thanks for your thoughts  . I believe the bodywork is exactly the same but the doughnut is marginally different - not importantly. Later suspension was of course lowered.

As I see it, it's a problem that was there before but I had to hit bumps much harder (faster) to get the bang. So, as speedbumps are usually in a 30mph zone, I never usually experienced it. Where I definitely have noticed the old suspension crashing before is on the open road, when I've hit a ramp - like a road re-surfacing or a pothole that's felt a lot harder than it should with a bang. These are usually one offs and difficult to compare as they are all different. I've been tackling the gap because that's where I believe the problem manifests itself.

Yes, fitting the coilovers has caused it to become a problem (actually just reduce the threshold speed) but I believe this to be for the following reaons:

1/ The coilover dampers are harder. The stiffer compression pushes the body up quicker and the stiffer rebound may allow the doughnuts to drop out of their hole as the body bounces off the rubber doughnuts.

2/ The coilovers have a shorter piston stroke, so may bottom out and cause the doughnuts to come out of their holes as the wheels leave the ground - earlier than standard struts.

3/ I have the car ride height set standard (670mm floor to arches (actually it's dropped to 660mm)), so the pistons will be nearer their end stops than with a lowered car.

So where do I go from here?

a) Put up with it - it's not as bad now with the Powerflex washers. It still happens because when I hit a bump and the doughnut compresses, a gap opens up under the Powerflex washers. The lesser bang I experience now is when this gap closes and the Powerflex washer suddenly hit the body.

b) Experiment with a softer material than Powerflex - perhaps to match the doughnut rubber.

c) Buy some K-MAC adjustable top mounts. They are ball jointed with no float gaps but they are well over Â£100. They may cause more road noise too.

d) Experiment with damper rates and ride heights - not too keen as a solution as I wanted to retain standard height - it might prove a point though. Lowering alone will show it's a piston stroke problem if it affects the speed threshold over the test speedbump :wink: .

e) Complain and get my money back? :roll: . Perhaps fit the same kit as you have (I wonder if the piston stroke is longer?). I'm a bit loathe to though. The Koni Coilovers do perform wonderfully in the main and I have to say I'm very impressed.


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## TTCool (Feb 7, 2005)

Perhaps you could start by emulating the sport setup by setting the firmness of your dampers at their softest and unwinding the springs so that you have a 25mm lower ride height, which would be 340/345mm from the centre of the hub cap to the edge of the wheel arch. Try that over the speed bump. If you find it's too soft, increase the firmness a quarter turn and try again without doing anything else. Firm the dampers up one quarter turn at a time. Remember you need to be on level ground to check the 340/345mm measurement with your tyre pressures the same on each axle and cold. You could count the threads on the damper so that they _should_ be equal but you would ultimately have to check and make sure the measurement from the centre cap to the wheel arch is OK. I'm assuming you can adjust the rear damping externally but if you can't, doing the front only might suffice. If there is an adjustment for rebound, why not set this to the middle of it's range. My rear damping is set half way and I haven't changed it yet.

Ignore what all this does to the camber and toe for the time being.

To be honest, John, I knew exactly where you were coming from when you said your were fitting coilovers. I was on the edge of doing the same but I can assure you that the Koni Sport and Eibach Pro setup will get you anywhere you want to be with regard to road holding, for road use.

I've just remembered, Dani has this setup hasn't she, and you've driven her car. Did you get any indication that there might be a problem. Probably not, as Dani has made no complaint. Can you perhaps drive her car over the same speed bump and see what happens ... Dani [smiley=smoking.gif]

By the way, what happens when you drive over cattle grids?

So far as the supplier is concerned I've no doubt that you are the first and they have fitted hundreds without a problem.

We will have to thrash this out when we stop for food on the NW cruise. Can you swim by the way? Perhaps we could tread water for a couple of hours :roll: The forecast is terrible, but it's not over until the mermaid sinks.

Joe


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## John-H (Jul 13, 2005)

TTCool said:


> ... it's not over until the mermaid sinks.


 :lol: Is that a fat mermaid perhaps?

I think Dani and most others have lowered on Coilovers so I'm being different. I wanted to avoid me having to slow to a crawl whilst approaching cigarette papers lying on the road so as not to cause the car to bottom out. They of course go very slowly over speedbumps.

I'll have to check but I may be a little under standard ride height - a quick calculation taking wheel radius off my floor measurements suggests 342mm (rim to centre) but that's not taking into account the deformation of the tyre which is why they specify rim to centre - only I find that tricky to measure.


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## HighTT (Feb 14, 2004)

John-H said:


> HighTT said:
> 
> 
> > ... Slightly off topic but if you hit speedbumps at an angle ( on-coming traffic allowing :roll: ) you will find that the whole experience is much less jarring
> ...


John - have you repeated your speedbump test using a person without an umbrella :lol: :lol:


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## John-H (Jul 13, 2005)

HighTT said:


> John-H said:
> 
> 
> > HighTT said:
> ...


That's not an umbrella Ian - that's his top retaining washer - I saw it bouncing off his head as he went over :lol:


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## Black Knight (Jan 16, 2007)

John-H said:


> Black Knight said:
> 
> 
> > Are you sure the strut rod/piston isn't touching/banging the chassis with sideways movement? It seems quite possible, even more possible to me than the strut top touching the chassis.
> ...


I just can't understand why you get a bang? The strut top washer already has a plastic/rubber thing that should not create a bang when hitting the chassis. It might hit it a bit harder, but I doubt it would be very audible like a "bang" sound or that it would create a sharp "knock" through the chassis, maybe a dim "thump", but definitely not a knock. And it is damn near impossible to get a bang if you added a powerflex washer in between?

Could the spring retaining washer(cyan) be hitting something? How can you be so sure it is the mount washer creating the bang? Sure, the chassis mount top is cleaned from dirt and the mount top washer may come in contact with it, but it may not be the source of banging?

Oh btw, I read that you had steering column problems before and it seems to be a common problem. How did it manifest? How did the steering play feel like when driving?


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## Black Knight (Jan 16, 2007)

John-H said:


> That's not an umbrella Ian - that's his top retaining washer - I saw it bouncing off his head as he went over :lol:


 :lol: :lol: :lol:


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## John-H (Jul 13, 2005)

Black Knight said:


> ... I just can't understand why you get a bang? The strut top washer already has a plastic/rubber thing that should not create a bang when hitting the chassis. It might hit it a bit harder, but I doubt it would be very audible like a "bang" sound or that it would create a sharp "knock" through the chassis, maybe a dim "thump", but definitely not a knock. And it is damn near impossible to get a bang if you added a powerflex washer in between?
> 
> Could the spring retaining washer(cyan) be hitting something? How can you be so sure it is the mount washer creating the bang? Sure, the chassis mount top is cleaned from dirt and the mount top washer may come in contact with it, but it may not be the source of banging?
> 
> Oh btw, I read that you had steering column problems before and it seems to be a common problem. How did it manifest? How did the steering play feel like when driving?


With the Koni's the spring top retainer is only small and well away from anything.










I'm pretty sure that the gap under the top washer is where the vibration - which is felt more than heard - is coming from. It has felt like the engine hitting the bulkhead - like something heavy on the loose but less so much now - and that's the point the powerflex washer has reduced it. I think it's still there to a smaller extent because the doughnuts will still compress and create a temporary gap under the powerflex washer, which when it closes will suddenly stop as the powerflex material is quite hard and a large surface area, so I still get some vibration.

I'm not discounting that it could be something else in addition. Roscoe Engineering say they have experienced this sort of thing too. It might just be the pistons hitting their end stops so lowering should raise the speed threshold of the problem when I go airbourne.


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## Black Knight (Jan 16, 2007)

Also wanted to say, those speedbumps of your look rather nice. You should see speedbumps in Croatia.. Anything over 15mph will surely break up something in the suspension.. they're pretty high with flat surfaces and ramps at sharp angles...

Here's a cell picture I took(was collecting pictures of unsigned speedbumps so I can complain to authorities)..










Try taking that at 30mph and something will definitely crack..


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## John-H (Jul 13, 2005)

Perhaps it's me going too fast over them that's the problem 

Those things are called cushions over here.

By the way I forgot to mention my steering column play was in the bottom sliding joint. It causes about 7mm of play at the steering wheel rim. Difficult to find, I had to lock the bottom UJ with two mole wrenches to the floor to tell. It's not a problem driving and with the DEFCON mod the steering has firmed up so much it's obviously much better. I've got another steering column to put on when I get round to it. You were allowed up to 1/2" play for an MOT in the UK but it's no longer specified.


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## Black Knight (Jan 16, 2007)

So you're still driving with it? The steering play doesn't bother you simply isn't noticeable? I mean 7mm of play is not that small given the pretty fast rack ratio of the TT, how does it not bother you?

Does it cause you to correct steering often? With road camber changes etc? Does it give you an unsafe wandering/floating feeling at motorway speeds? Or wandering while hard braking?

The TT steering was so nice, just how I like it, before mine developed play..
Maybe you just can't remember how nice it was and have grown used to the play?
There's nothing worse for me than bad steering.

I'm still trying to figure out where the play is in my steering. Everything points to the steering rack but noone is really sure enough before disassembling it and it is a job to disassemble it for nothing. 
The thing that bothers me the most with the steering rack or steering column theory is what I managed to do on the motorway. Brake a bit harder and the steering wheel turns to the left at least 5 degrees, release the brakes and the steering wheel returns to center. All the while the car is going straight ahead. I can't repeat it on demand on every bit of road, but when I did notice it, I repeated it on purpose several times and it happened every time. That kinda puts me off the steering rack or steering column idea. If the wheels remained straight during braking there would be no reason for the steering wheel to move out of position because of play in the steering rack or column?
The only thing I can imagine causing that is something else allowing play causing the wheel to move out of position(backwards for example) but still keep going straight which would cause movement in the steering rack
I've replaced the bushes and it didn't make any difference.. Dunno, maybe to replace strut mounts perhaps? Or ball joints? Shouldn't the bottom ball joints knock a lot when worn?


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## John-H (Jul 13, 2005)

I find the TT steers straight and doesn't wander much on th emotorway even when going in the dips caused by heavy lorries braking near exits. I think this is basically the bottom end, rack, steering arms etc. being is a sound condition. I find I don't have to correct the steering. It's certainly better than my Escort RS which does tent to wander up and down ruts a little. Perhaps I've got used to it but I noticed a marked increase in feel, feedback and response to steering wheel twitches with the DEFCON. In comparison it feels like a quick rack on a rally car now.

Worn ball joints usually rattle over road repairs, broken tarmac and pot holes etc. in my experience. It could cause you toe and changes.

Thing is, if you let go of the steering wheel, brake and see the wheel move but you still drive straight, I would have thought that's play somewhere being taken up due to the forces created by the scrub radius of the wheel offset (worse with spacers) - where the wheel alters toe on one side - but if you've let go of the steering wheel the castor angle shared between both sides cause the rack to move so the forces equalise between both sides and the car continues to drive straight.

With a worn wishbone bush or ball joint the end of the strut can move to alter toe but castor and camber too. If castor/camber moves the car gains thrust angle and will steer to one side I think moreso with castor. So therefore castor/camber is not moving merely toe, which causes centering correction in the rack because of the forces being linked and averaged one side to the other with a free rack.

With a tie rod inner or outer play you will just get a toe change causing the steering rack movement and not thrust angle. So, if my thinking is correct that points to tie rod ends inner or outer. Try jacking the wheel off the ground and grabbing quarter past nine and rock - see if there's play.


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## Black Knight (Jan 16, 2007)

That does make sense and it would then point to the right tie rod, but I've tested the tie rods several times, dry park, lifted, all kinds of tests..
The only thing I've noticed is that you can feel knocking inside the steering rack when the steering wheel is rapidly turned left-right..This is what pointed to the steering rack. But I'm not sure any more, it was a while ago, I think this was tested with the engine off. I was later told that this is normal when the engine is off and servo oil pressure is not built up?

I also can't see why, if the slack was taken up by the braking, it returns back after I depress the brake(no throttle, just coasting)? Also, the amount of steering wheel movement when applying the brake seemed exactly proportional to brake pressure or maybe even diving action. I could literaly control how much the steering wheel would offset from center by varying brake pressure.

Another thing, that I can definitely repeat whenever I want, is steering into the camber of the road. I need to steer into the camber to keep the car going straight. The amount of steer into seems to be proportional to the camber of the road and usually in the range of the steering movement I described under braking. The amount of "steer into" isn't dependant on vehicle speed. I can't remember though if this happens on both sides, road is cambered usually in one direction that makes me steer left into it. Can't remember if it works the other way, gotta find a bit of road with opposite camber to check.
I am so used to this behaviour now that I start steering into road camber in advance, just as I enter the camber so the car doesn't swerve off the camber. I prepare myself in other words. And I steer back to center after the cambered road again to keep the car going straight.

I'm sorry to be jacking your subject  But it seemed it was exhausted a bit


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## Black Knight (Jan 16, 2007)

I just went outside and did a dry park test with a friend. I held the tie rods as he rapidly turned the steering wheel. I couldn't feel any play in the outer joints and I can't really reach far enough to get a good feel of the inner joints, but what I did hear and feel is knocking. It is felt on both sides through the tie rods and when holding the steering column shaft where it is accessible inside and it seems to be coming from the steering rack or perhaps rack ends. It is there at all steering wheel angles, center, full left, full right. This time the engine was definitely on.

Buh, I'm just waiting for it to grow more obvious, but it doesn't seem to want to do that.. It is just annoying me..


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## John-H (Jul 13, 2005)

Black Knight said:


> ... the amount of steering wheel movement when applying the brake seemed exactly proportional to brake pressure...
> 
> ... I'm sorry to be jacking your subject  But it seemed it was exhausted a bit


My broadband's gone down so I'm on dial-up but I saved this post from befere:

Don't worry, you're pushing it up the list by posting and maximising the number of people who might chip in with an idea. :wink:

Yes, they do make noises when rapidly turned left to right. The knocking you're hearing could well be the damper mechanism that presses the pinion gear and rack together. There's a required amount of play and the slack is taken up by a spring which pushes on the back of the rack and presses it into the pinion.

If you're describing a proportional effect with the wheel turning under braking that sounds like there's something springey in this situation. If we've discounted rubber bushes I wonder if the damper spring could cause this? The pinion is off centre in the rack so as you press the brakes and the compression forces in the tie rods and rack increase, the rack will tend to lift against the damper spring and allow more toe out that side, which will be centred by the castor and turn the steering wheel left on a RHD car and right on a LHD car. I'm not sure of the amount but that would seem to tie in at least a bit. If that matches then perhaps you can adjust the damper play? - there's an adjustment on the ZF rack.


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## HighTT (Feb 14, 2004)

Black Knight - it sounds as if you have a bump-steer
or some kind of rear wheel steer problem or maybe 
a brake caliper problem.

John - my car used to follow the dips made by HGVs near motorway exits
when I had Pirelli P-6000s. I got rid of the tyres and I've mainly got rid of the problem.

I feel that all these geometry and braking problems are really hard
to diagnose on the TT because I think that all the electronic systems
designed to keep us safe are muddying the waters by attempting to carry out corrections.


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## Black Knight (Jan 16, 2007)

HighTT said:


> Black Knight - it sounds as if you have a bump-steer
> or some kind of rear wheel steer problem or maybe
> a brake caliper problem.
> 
> ...


I actually wrote down that it sometimes feel like one of the wheels has a funny bumpsteer curve, but I deleted the message 

It can't be a brake caliper problem. 
I can feel it present most of the time, regardless of brakes. Best examples are steering into road camber to keep the car going straight, feeling of floating and looseness when driving over really rough roads and feeling of toe change when turning sharp and varying throttle. 
It doesn't have anything to do with tires, I replaced them because they were a bit worn, could have lasted longer but I was sure it wasn't the tires even though everyone thought that would be a good bet. And guess what, it's still the same.
Tires can in no way induce floating or steering play sensations.
My car does follow road crown as any other, the problem is the steering play/looseness. Imagine the road crown pulling the car into one direction, now imagine there's play in the steering. The road crown pulls the car, the car starts going into a different direction and then finaly the slack in the steering gets taken up and then the steering wheel then also starts pulling in that direction. You can't stop the car from swerving all over the road crown as you have 10-20mm of play and the pulling keeps changing direction and taking up and releasing the slack at either side randomly. It's very annoying.
Also, the car often swerves to one side when heavy braking to a stop. It was usually the left side, but that may be because road is usually cambered to one side. And by swerving to one side I mean it swerves left all the while I hold firmly the steering dead on the center and do not feel a thing in the steering wheel and the car manages to change direction. This is an awful feeling of lack of control.


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## Black Knight (Jan 16, 2007)

John-H said:


> Black Knight said:
> 
> 
> > ... the amount of steering wheel movement when applying the brake seemed exactly proportional to brake pressure...
> ...


You mean the preload spring adjustment we talked about before? I've talked to several mechanics and they said nothing good ever came from adjusting that... but I guess it costs nothing to try :/ 
My car is LHD and the steering wheel turned left?  But as I said, the direction might be dependant on road camber.

The knocking I hear is a bit sharper lighter knock. Like tapping bodywork with a narrow long screwdriver or something. Something between a knock and a click.

Funny thing is when doing a dry park test it seems there's no slack at all, the wheels respond to the tiniest bit of movement from the steering wheel. Same thing when driving, it seems the car changes direction with the tiniest bit of turning the steering wheel, when going straight on a flat road. You can't really feel or find the slack, as in a few degrees of steering wheel movement where it feels empty of resistance. But it still always feels unsharp, sloppy, vague, mushy, unprecise, elastic. Does the TT have some kind of a damper that dampens steering wheel movement? On my old calibra I could very well feel the slack in the steering whel, you could feel exactly when you've taken up the slack by turning the steering wheel and at which point the wheels start responding. It is not like this on my TT. It is similar, but there is no empty slack, more like the slack isn't slack but an area where the steering response is mushy.
Maybe it could be the preload spring? Because it feels springy as you've said. Or perhaps there are some bushes holding the steering shaft in place or something that have gone soft or something allowing the steering input shaft to move sideways in the rack? Like, you turn the steering wheel and a part of the torque goes into the rack and turns the wheels and a part of the torque deflects off the rack to move the input shaft sideways? Something like that. This allows the wheels to respond to even tiny movements of the steering wheel, but if you make rapid movements more of the torque deflects and moves the steering input shaft instead of the wheels? Or something like that?


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## Black Knight (Jan 16, 2007)

btw. why does vagcat list different racks for V6s? what exactly is different? i thought i read somewhere V6 racks are faster but couldnt confirm it anywhere or find the original quite?


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## John-H (Jul 13, 2005)

What you say about slight movements moving the wheels but sharper ones additionally moving some springey element sounds exactly right for your symptoms. Whether that's the damper adjustment or some soft bushing is difficult to pin down. Obviously it happens more when the forces in the linkages are greater.

Another possibility may be loose rack brackets allowing the rack to move at one end.

I thought of a test. If you could somehow clamp the wheel rims so there could be no movement of the wheels at all, then turning the steering wheel should show up exactly where this springey movement is. Possibly you could do it in one direction/wheel at a time by parking the car as close as possible to a wall, then jamming some wood in between the wall and the wheel rim edge. With the engine running, turning the steering wheel, so the wood is compressed against the wall should make the rack forces become much greater and perhaps the play would them become obvious. Watch you don't damage your alloys though. Use some soft cloth or rubber over the wood

I can see all the different racks but in Ekta but it doesn't list the differences other than the whole item part numbers. :?


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## Black Knight (Jan 16, 2007)

John-H said:


> Another possibility may be loose rack brackets allowing the rack to move at one end.


Funnily enough, I also keep complaining about steering wheel vibration, but not shimmy, vibration, more like up-down vibration when at high speeds and it seems to happen with road surface irregularities being taken at high speed, it's like they transfer to the steering wheel. It was a lot worse also when the tires were overinflated(when I first got the car), about 4-5mm up/down vibration with the steering column fully extended. This I noticed long before the steering play started. I suspect this is not normal behaviour? I'd expect it from a Lada, but not the TT..

Btw. will clamping the wheels and then trying to turn them kinda strain the whole thing? Servo pump? Any difference if I do it with the engine off?


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## John-H (Jul 13, 2005)

Black Knight said:


> John-H said:
> 
> 
> > Another possibility may be loose rack brackets allowing the rack to move at one end.
> ...


The forces in the rack will be the same whether the wheels are clamped or not - it just depends on how hard you pull on the steering wheel. There can be a lot of force at the wheels enough to damage paint - I know I damaged my alloys like this on a brick wall - hence the need for something soft to protect them. I'm not suggesting you are too forceful with the steering wheel - it's just that having the wheels locked will show up where the play is more easily as you turn the steering wheel with as much force as in normal driving/parking. It's difficult to spot play with the whole thing moving.

With the engine off you are more likely to show up play in the steering column.


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