Steering Wheel Wobble Under Heavy Braking - S3 8l

rolto1822

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Hi guys,

Thought I'd post up here as there are a fair few of you running these cars hard on track.. I had a recent trip to the Ring (where a lot of fun was had, first and foremost) - but under hard braking, the whole front end of my car seemed to shake, and the steering wheel would shake fairly violently. Didn't give me all that much confidence under braking, not ideal..

Anyway so the first suggestion I'm sure will be brakes. Rotors are fairly new, pads being used at the time - Ferodo DS3000. In daily use there is no noticeable issue, likewise under heavy braking whilst on the track, the braking effort was continuous as one hopes. I have had the "warped rotor" issue before (owned a Jeep.. let's not talk about it), and this is not that, i'd say for 99% certain. Again: the feel is through the front end and wheel, rather than the pedal and a non-consistent brake feel.

My thoughts are with bushings, particularly control arm bushings.. I have, however, had the car up off the ground and had a poke about, and a good wiggle, and nothing struck me as being of particular issue, aside from:

with both front wheels off the ground, when you manually (car off, parked) steer one wheel, the other did follow suit, but there was a small amount of play between moving one and the other moving in kind. No idea if this is to be expected (possibly just slack in the gears in the rack?)..

Bushings all appeared to be ok, putting a decent amount of force and using the wheel brace as a lever too (though just the little factory audi one), nothing moved that shouldn't do.

Car has to go in for the infamous German TÜV inspection next month and I'm worried that this may cause issues.. Would fix it if i knew what it was!

Again - during every day driving I can't detect any issues whatsoever (hence I'm hopeful for the TÜV inspection) but I'd like to get it sorted ASAP nonetheless, and certainly before the next Ring trip!

Any help/suggestions etc. is much appreciated at this point. I can't afford to take it to a garage and just throw money at them to find the cure.

Cheers! :tup:

Sam
 
hopefully when you are using that brace (albeit too small really) its with the wheels on the ground, with all the tension off the suspension components in my experience that method won't show much up unless the item that is worn is ready to fall apart really, needs to be done ideally on a 4 post ramp so the wheels are weight loaded
 
How many miles have you covered since the ring laps Rolto?

DS3000 are very good pads, but can be prone to depositing pad material on the discs during heavy use, which leads to a shudder under braking usually felt through the whole front end, and not the pedal.

I used to find it would typically vanish after 1-200 miles of road use.

One thing - you mentioned pads used 'at the time'

Does this mean you have since changed to other pads? if so, this will almost certainly be the issue. Ferrodos leave large amounts of pad deposits over the surface of the disc that don't usually cause any issues, but when changing compounds to other makes of pad, these often cause issues with judder.
 
@jojo - is this doable DIY style or is it worth paying someone else for the hassle? Track arm = control arm to confirm?

@jasongtr - the wheels were off the ground, don't have access to a four post lift sadly, though might it be worth me having another look with the vehicle on the ground?

@Prawn - Probably done a hundred miles or so. Had this last time I did a track day too, same pads. As much as anything else i'd expect the rotors to get wiped clean with a hard and consistent brake or two? I'm running OEM equivalent pads otherwise for road use, same rotors.. I don't really get how using a different pad with the same rotor and same quantity of potentially uneven pad deposit on it would change such characteristics? - Very happy to be wrong here. New rotors are not expensive.. would be keen to not have such an issue on track though so what's the real solution, since that's where i'm experiencing this.

@ALL - Here's a video of one of my laps, 4:29 under braking you can hear the shake from the steering wheel. Wheel shook very violently left to right.. It happened throughout the lap, I just remember it being particularly noticeable there (and I actually commented on it at the time)

 
Update- Went to go and give her a run around today. and she's been sat for a bit as I don't use her daily at the moment:

After accelerating and then letting off the accelerator pedal, there was a knocking sound, heard a good few knocks each time I did that; did it for 5 mins or so of driving about, then stopped doing it. Not sure if this could potentially be to do with her being sat for a while? Thoughts are again going towards bushings, maybe CV joints? Again bit confused by the fact that it went away?

Love cars but not loving them at the moment, at all =P

Again, any help or suggestions are much appreciated - also further to the braking issue! I'm not totally against buying new rotors and pads for the street, though still want to know what would be best to do with the Ferodo pads for when on track? They've got life yet and not as disposable as OEM equivalent stuff.

Sam
 
Just went out again and the knocking was noticeable whilst driving, in third and fourth most notably (didn't get up any higher than that though). Noticed a knocking sound coming from the back end, so probably drivetrain related. Knocking also reproduced when changing into 4th (letting the clutch up) from third.