Front camber advice

[sambb]

Cool. I'll be really interested to see how the TT conversion goes so I'll be checking in. Do you have a build thread or anything to keep an eye on or is here the place.

[Sirocco20348]

Wow it's been almost a year since the last post. I haven't completed the install yet, as life has got in the way etc..

But today I chanced upon a set of Audi TT control arms with the little extra bit of metal to drill into. So hard to find, but I can now keep my original shine suspension.

I'm expecting my control Arm angle to be similar to this. Hopefully installed over the next few weeks.

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[dylan8]

Getting that control arm closer to level and the improved control over alignment settings made a huge difference in my car even without the sway bar. You'll enjoy it.

[Sirocco20348]

Wow.. huge surprise when I opened the box today!!!

Can anyone else notice why I'm super surprised??

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These are some rare pre-recall Audi TT Control Arms. You can tell from the size of the small bushing.

They were recalled because of a number of deaths that happened on the autobahn in Germany when people attempted high speed lane changes. The tighter setup would induce unexpected oversteer and most people were not experienced enough to recover it, resulting in massive crashes.

Audi Offers TT Fix After 5 Deaths - The New York Times

I also noticed that the other big rubber Bush is not solid like in the post recall control Arm.

I never expected to find a set in Australia...

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[sambb]

That's interesting. I read a piece by a guy in the **** Shine camp talking about the Mk1 TT issues and it was saying that it was the camber gain properties of the hub that was at fault. ie its positioning of the pivots. The story said that the hub design was too good resulting in excellent camber gain properties ie it wouldn't loose camber relative to roll angle and go into factory dictated understeer beyond 8/10ths. It was actually maintaining its static camber angles throughout roll and basically getting to the point where it would keep holding in and gripping until the tyres just let go. The inexperienced driver could'nt read that this was about to happen and lost it. However your story says that an ex-rally guy died so who knows or was he just pushing big time? I vaguely remember that the control arms were changed too but I'm not sure. So if you got pre recall ones I would love to see what angles they produce for caster and camber and what kind of track they produce.

[sambb]

makes me wonder if the entire sub frames in the polo 9N3 gti can be changed and these control arms be fitted.

[Sirocco20348]

The Ex-rally guy may have been doing 300km/h on the autobahn. Mistakes happen.. geez I've known about these for a while, but expected nearly all to have been destroyed during factory servicing.

Of further interest, some guys rate the pre recall arms so much they fabricated their own inserts for the MK2 control Arm.

Defcon Bushes

Hey Sam, Can I ask your opinion about the below. You have been living and breathing optimal geometry etc for some time now.

What I think might happen once I put on the TT Hubs with the shine suspension, which positions the ball joint 1.33" lower. Is that the inner pivot point of the control Arm will be higher than the ball joint (as per the schematic picture in the above post. Any concerns? All online articles I read about MacPherson struts say that it is not a problem, but I am not sure where that puts the roll centre etc on the mk4.

Also I'll be using the pre-recall control arms with the 20mm Mk4 FSB instead of the 19mm. I honestly have no idea what this car will drive like.

I don't want to compare my car to a race car with 100% fabricated hubs, custom suspension, but the Frazero Mk4 race car has an interesting choice of control Arm and sway bar. They use the poverty spec stamped control arms and thicker Mk4 sway?!

Haha so I'm really confused but there are some great fabrication pictures in here...

Yellow Frazero Mk4 | Club GTI

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[sambb]

No not all. If the inner pivot is higher than the outer, that will push your roll centre up higher towards the centre of gravity and make it handle better. That's the whole point of roll centre correction kits etc its so that you can run the car low without adversely affecting geometry. The control arms level idea is so that if you don't have roll centre correction, its considered the limit you would take the pivots too without mangling geometry/handling. Thetheoretical point taken for centre of gravity is about crank height normally. Even with your control arms slightly angled up towards the inner you wouldn't get near that I don't think, but the closer the better. Basically my car went from stock height, to H&R fronts which were way too low and had the outer pivots much higher than the inners, raised again with weitecs which put the arms just about level, back to stock after that. Considering that all those springs had identical spring rates to factory, the only thing I was changing was geometry and the H&R's were appalling (way too low), the weitecs were much better (control arms level but still slightly up on the hub end) and stock were the best (level). I now have changed over to 400lb fronts MCA coilovers and I think I'm even a tad higher than stock and it is a proper change for the better, so control arms angling up towards the inner pivots has been nothing but an improvement for me and it aligns the steering arms for less bump steer to boot.
Re the race car using the pre recall control arms I don't know what the difference is between them. Do the ball joint positions create more caster or give wider track. I'd guess that they'd use the ones that give better angles. For front anti roll bar it comes down to how much rear anti roll you'll have. eg if you put the 20mm on and cant get stiff enough rear springs and/or bar into it then it'll want to understeer more, so the front bar choice is a bit more holistic looking at what the whole picture will be. But then again 19mm vs 20mm isn't a huge jump so you cant go badly wrong either way. Are both bars droplinked onto the control arm or does one of them droplink off the strut as off the control arm would be the pick.

[Sirocco20348]

No not all. If the inner pivot is higher than the outer, that will push your roll centre up higher towards the centre of gravity and make it handle better. That's the whole point of roll centre correction kits etc its so that you can run the car low without adversely affecting geometry. The control arms level idea is so that if you don't have roll centre correction, its considered the limit you would take the pivots too without mangling geometry/handling. Thetheoretical point taken for centre of gravity is about crank height normally. Even with your control arms slightly angled up towards the inner you wouldn't get near that I don't think, but the closer the better. Basically my car went from stock height, to H&R fronts which were way too low and had the outer pivots much higher than the inners, raised again with weitecs which put the arms just about level, back to stock after that. Considering that all those springs had identical spring rates to factory, the only thing I was changing was geometry and the H&R's were appalling (way too low), the weitecs were much better (control arms level but still slightly up on the hub end) and stock were the best (level). I now have changed over to 400lb fronts MCA coilovers and I think I'm even a tad higher than stock and it is a proper change for the better, so control arms angling up towards the inner pivots has been nothing but an improvement for me and it aligns the steering arms for less bump steer to boot.
Re the race car using the pre recall control arms I don't know what the difference is between them. Do the ball joint positions create more caster or give wider track. I'd guess that they'd use the ones that give better angles. For front anti roll bar it comes down to how much rear anti roll you'll have. eg if you put the 20mm on and cant get stiff enough rear springs and/or bar into it then it'll want to understeer more, so the front bar choice is a bit more holistic looking at what the whole picture will be. But then again 19mm vs 20mm isn't a huge jump so you cant go badly wrong either way. Are both bars droplinked onto the control arm or does one of them droplink off the strut as off the control arm would be the pick.

Ok Awesome! You certainly have been through some spring sets...In regards to the FSB attachment point, I'll be connecting them to the control Arm. I just have to drill into the control arms to make connection points.

That's fascinating that the MCA'S are above stock height, how did you acheive that. The minimum drop I've seen on coil overs is like 1.5". Heavy Springs rates as well, would be keen to see what they are like. Did you request those rates through MCA?

The race car doesn't even have the cast Audi TT control arms. It's uses the stamped steel Mk4 golf arms which are apparently 'inferior' because of flex. Maybe it's a cost/benefit part because their isn't any difference in the actual size of the control Arm, just that the audi has adjustable camber and the smaller bush at the rear. They would take care of camber, castor etc from to mounts more than likely.

I'll be surprised if caster and track are changed at all with the pre-recall control arms..



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[sambb]

No the MCA's out of the box are height adjustable but more for a lower ride height. They are adjustable height coilovers so I was able to try different heights far easier than full strut/spring changes like previously. They came with 180mm springs and I actually changed over to 200mm springs recently so that I could run them more effectively up around stock ride height eg run them higher and keep a good bump:droop ratio
I got some pretty solid advice re spring rates from race engineer. They differed to what the kit was sold with but MCA are pretty good with that. MCA are a bit more biased towards running lots of spring and less bar, but the spring rates I was advised to go with were based on the tracks I run on and the max lateral G that say 205 r spec semis can handle so we went for softer springs than MCA wanted. The damping is adjustable which could account for the change. A pair of springs is only a hundred bucks if you purchased through them so you can chop and change cheaply. I have 7kg/mm fronts and stiffer 8kg/mm rears. With motion ratios etc that comes out at about square wheel rates all round of 380lb/in or so. Front 22mm bar, rear 20mm bar, toe out front and rear and the MCA's came with adjustable camber tops so I've got 3-3/1/2 up front and 1/1/2 rear. With caster bushes, that subframe mod I mentioned at the start etc I have 5/3/4 degrees pos caster.
Oh ok sorry I thought it had non recall TT arms. Yeah not sure maybe they figured those arms were strong enough and used them to keep unsprung weight down?