Vibration on braking and dry steering - Suggestions?

[Meemo]

Sorry it is a long one I have also posted this in the technical handling section.



So my b8 is being plagued by a vibration issue which has now left the car feeling dangerous and undriveable and me clueless.

It feels unstable and notchy and on braking it vibrates so hard the steering wheel shakes, like when you drive over the traffic control lines coming off the motor way or into a 30 (and then some). it was having these issues but bareable up until I bottomed out last week and whatever it was is now fudged good!



I have had all 4 disks and pads changed. it was vibrating on brake before and this solved it for a few months.

But few months later it came back, so changed a sticking caliper for a new one at the back and another set of new disks and pads. but the issue seems worse!

the fronts dont seem to be sticking so is unlikely warped at the front but I wont rule it out.



when the car is stationary when i dry steer at 3 points in the steer i get a distinct vibrate noise and feel in the steering and peddles, audible outside and in. We checked with the car off (so no power steering) and turned the wheel whilst someone had their hand on the steering rack underneath, and they felt the vibration through the steering rack (I really hope it isnt).



on driving the steering occasionally has a spack and suddenly pulls hard towards a dip or bump, physical turns the steering out my hands hard. I have driven this car since 2013 and it has never behaved like that, it feels awful and something is definitely broken.



Also had the control arm bushing and wheels bearing changed recently at the front. It is due a proper tracking but not bothering incase the front comes appart to fix this issue.



Any one want to play sofa mechanics? would appreciate some ideas of what to look at next, really appreciate any suggestions

 

[Meemo]

car is on air incase that is also important.

 

[jaygemson]

Hey Manda,

Regarding the vibration under braking, I have exactly the same issue on my old 2010 B8 S4. Under braking the steering wheel pulls left-to-right quite violently, depending on road speed and pedal pressure. It's been that way for the last 15k miles, the car now having covered 37k. As you said, new discs/pads solves the problem initially only for it to return a month or so later.

I solved the issue temporarily by having my discs skimmed whilst they're still on the car. This takes into account any run-out in the hubs, and after this braking was lovely and smooth until I needed new discs and the old vibration was back again.

I've changed the following in an attempt to track down the root cause:

• Brand new wheels (Team Dynamics Pro Race 1.3 - with no spacers or spigot rings)
• Brand new discs (sourced from DaveB @ vagbremtechnic, but I had the same issue with OEM Audi discs too)
• Brand new hubs and bearings (sourced and fitted by Audi Basingstoke)
• Brand new dampers and springs (OEM Audi adaptive dampers and KW height-adjustable springs)

And the vibration remains. The car is going to an independant specialist on Monday to have the front suspension checked and discs and hubs measured for run-out. I'm still convinced that it's run-out in the hubs, and if so it's going back to Audi, but I'll be sure to report back with any updates/findings.

 

[Meemo]

Hey Manda,

Regarding the vibration under braking, I have exactly the same issue on my old 2010 B8 S4. Under braking the steering wheel pulls left-to-right quite violently, depending on road speed and pedal pressure. It's been that way for the last 15k miles, the car now having covered 37k. As you said, new discs/pads solves the problem initially only for it to return a month or so later.

I solved the issue temporarily by having my discs skimmed whilst they're still on the car. This takes into account any run-out in the hubs, and after this braking was lovely and smooth until I needed new discs and the old vibration was back again.

I've changed the following in an attempt to track down the root cause:

• Brand new wheels (Team Dynamics Pro Race 1.3 - with no spacers or spigot rings)
• Brand new discs (sourced from DaveB @ vagbremtechnic, but I had the same issue with OEM Audi discs too)
• Brand new hubs and bearings (sourced and fitted by Audi Basingstoke)
• Brand new dampers and springs (OEM Audi adaptive dampers and KW height-adjustable springs)

And the vibration remains. The car is going to an independant specialist on Monday to have the front suspension checked and discs and hubs measured for run-out. I'm still convinced that it's run-out in the hubs, and if so it's going back to Audi, but I'll be sure to report back with any updates/findings.

Thanks Jay, I am passing my car to the guys who fitted my airride @olethalb and Chris .
Looking into my symptoms across forums (dangerous I know) it can be caused by Droplinks which will cause vibration on braking and highspeed, both of which I have, or alternatively Engine mounts.
Will let you know if we resolve it too dont like the idea of skimming another set of disks :'( just had the backs skimmed this week as that's what we thought was causing it.
Good luck!
Manda

 

[Meemo]

I also had a wheel bearing changed recently.. they can cause run out, will have to measure the runout and see if chucking money at it for a front skim might help.

 

[jaygemson]

Interesting point about the drop/end links, I'd read similar things on other forums too. They're not too expensive so definitely worth a shout. A master tech at Basingstoke Audi confirmed that there wasn't a recall on the control arms though, I've also read that people have replaced those to resolve motorway-speed vibrations but not vibrations under braking.

The thing that makes me believe it to be hub run-out is that I can hear my front discs catching through the calipers once per rotation (a subtle "hiss... hiss... hiss" when driving slowly next to a wall/fence) so they're clearly not running true despite being brand new. If the hubs and bearings have been replaced with brand new Audi parts there should be zero run-out, but I'll find out for sure on Monday!

Would definitely be interested in seeing whether you have any run-out on your hubs and discs too.

 

[Meemo]

Interesting point about the drop/end links, I'd read similar things on other forums too. They're not too expensive so definitely worth a shout. A master tech at Basingstoke Audi confirmed that there wasn't a recall on the control arms though, I've also read that people have replaced those to resolve motorway-speed vibrations but not vibrations under braking.

The thing that makes me believe it to be hub run-out is that I can hear my front discs catching through the calipers once per rotation (a subtle "hiss... hiss... hiss" when driving slowly next to a wall/fence) so they're clearly not running true despite being brand new. If the hubs and bearings have been replaced with brand new Audi parts there should be zero run-out, but I'll find out for sure on Monday!

Would definitely be interested in seeing whether you have any run-out on your hubs and discs too.

So my guy reckons its these grooved dimpled disks, and they are tearing chunks out of the pads. So i am getting some pagid ones on and sending these back to the company I got them from, hopefully get a small amount of my money back although I am not hopeful, but they have been very compliant and asked for them back to be inspected.

The vibration on the steering turned out to be nothing more than a bent heat shield rubbing on the ball joint when i steered (this must be what I bent when I bottomed out), I had this noise a long time but go so much worse after smashing the underside of my car. So pleased it was not a steering rack!

I squirms horribly under brake, the steering is all over the place, but he is confident if I ditch these disks the problem will go away, I will get the car tracked and am swapping my wheels so the real test will be if it comes back for a few months like before.

I really miss having a car currently even if it is a piece of poo lol

How you getting on with yours?

 

[jaygemson]

Always nice to find a simple fix to a potentially expensive issue! You must be over the moon. I really hope that the discs do the trick for the vibration - keep us updated if you can.

The only update from my side is that a fairly serious amount of run-out has been measured at the discs, particularly on the driver's side. The hubs weren't measured though so I can't say for sure whether it's discs or hubs at this stage, but I'm going to get a second opinion as soon as I can. I'm also in discussion with my disc supplier for a potential replacement set. Watch this space!

 

[jaygemson]

Second opinion is in, and this is one that I trust. Marcus from diskskimmers.com kindly came out to see me today, an ex-Williams F1 engineer with a mobile laith, years of experience and a methodical approach to fixing brake vibrations.

Within 20 minutes he'd found the problem - the new hubs aren't straight! He measured >0.5mm runout across the whole surface of each disc, and around 0.15mm on the hubs (driver's side was slightly worse). He's providing me with a written report to take to Audi in order to facilitate the replacement or re-fit of the hubs and bearings.

So the saga continues for me, but hopefully I'll have some comeback at Audi and they can get it right second time around.

How's your car Manda?

 

[Meemo]

Second opinion is in, and this is one that I trust. Marcus from diskskimmers.com kindly came out to see me today, an ex-Williams F1 engineer with a mobile laith, years of experience and a methodical approach to fixing brake vibrations.

Within 20 minutes he'd found the problem - the new hubs aren't straight! He measured >0.5mm runout across the whole surface of each disc, and around 0.15mm on the hubs (driver's side was slightly worse). He's providing me with a written report to take to Audi in order to facilitate the replacement or re-fit of the hubs and bearings.

So the saga continues for me, but hopefully I'll have some comeback at Audi and they can get it right second time around.

How's your car Manda?

That's great news for you, so new hubs should fix it? (fingers crossed).
No further news on mine, is still with my car whisperer, he works on it when he can in the evenings.
Will let you know what he says about the hubs on mine as i linked him the thread (worst kind of customer me... The sofa mechanic haha)

 

[Chop.]

just reading all this now, iv heard some bad reports about some types of grooved and drilled disks, when you replaced your first lot of discs were they grooved and drilled same make ?

hope you get it sorted nothing worse than motor troubles

 

[Meemo]

just reading all this now, iv heard some bad reports about some types of grooved and drilled disks, when you replaced your first lot of discs were they grooved and drilled same make ?

hope you get it sorted nothing worse than motor troubles

They was oem but had vibration so had them changed to these grooved and dimpled ones. I had a seized caliper and a wheel bearing since then So hoping that was what made this set bad + the grooves tearing up the pads.
Getting pagid ones put on now and will see how it goes and if it comes bk again after a few months

 

[Chop.]

Was thinking if it had been same discs then you'd found it but not so sure now

Are Both caliper slides and Pistons free on the front, is it only under braking ? Have you had front wheels ballenced

 

[Meemo]

So new disks all round and i have no knocking nor vibration fingers crossed they hold and that the wheel bearing going was to blame @chop @jaygemson

 

[Chop.]

Good job glad it's sorted, did you go grooved and drilled

 

[jaygemson]

Awesome news Manda! Thanks for the update.

No change this end for me - waiting on Audi to replace their broken dial gauge (convenient eh!) before it can go back in. I'll update you when I know more!

 

[Meemo]

Awesome news Manda! Thanks for the update.

No change this end for me - waiting on Audi to replace their broken dial gauge (convenient eh!) before it can go back in. I'll update you when I know more!

Never know, it could always come back if it wasnt caused by the wheel bearing. Which I think was caused by my wheels not being properly balanced. Visious circle.

Let me know what happens with yours, they refitted the hubs again and checked the droplinks?

 

[jaygemson]

Update!

The car went into Audi this morning and I watched as the run-out was carefully measured, the result of which is as follows:

Driver's side - hub only: 0.05mm (Audi official tolerance 0.02mm)
Driver's side - brand new Audi S4 disc (345mm): 0.2mm (Audi official tolerance 0.06mm)
Driver's side - AP Racing disc (362mm): 0.25mm

There wasn't time to measure the passenger side, but we'd seen enough to convince the master technician that the hubs are not true. They are being replaced under warranty next Friday, and measured for run-out after installation to ensure that they're perfect. Watch this space!

 

[Meemo]

Update!

The car went into Audi this morning and I watched as the run-out was carefully measured, the result of which is as follows:

Driver's side - hub only: 0.05mm (Audi official tolerance 0.02mm)
Driver's side - brand new Audi S4 disc (345mm): 0.2mm (Audi official tolerance 0.06mm)
Driver's side - AP Racing disc (362mm): 0.25mm

There wasn't time to measure the passenger side, but we'd seen enough to convince the master technician that the hubs are not true. They are being replaced under warranty next Friday, and measured for run-out after installation to ensure that they're perfect. Watch this space!

How you get on?

 

[jaygemson]

Hey Manda!

New hubs and bearings are being fitted on Monday - not long

 

[jaygemson]

New hubs and bearings fitted under warranty, problem remains

Audi recorded video evidence of the run-out measured before and after the replacement parts were fitted. Official tolerance at the hubs is 0.02mm - the car came into the workshop with 0.06mm of run out at the hubs and left with ~0.01mm. Drove 30 miles home and the car felt great with no vibration at all on the old RS5 wavy rotors. I then fitted the new discs and the vibration issues came back again.

This video shows Audi's before and after clips, as well as the new discs dragging in the caliper once per rotation:

So at this point I'm thinking that not only were the hubs out of tolerance, but the new discs are also out of true. The car's off to Storm Developments today for further diagnostics (e.g. checking the drivetrain for any distortion).

Manda, how's your car been since your last update? Still smooth and trouble free I hope!

 

[Meemo]

New hubs and bearings fitted under warranty, problem remains

Audi recorded video evidence of the run-out measured before and after the replacement parts were fitted. Official tolerance at the hubs is 0.02mm - the car came into the workshop with 0.06mm of run out at the hubs and left with ~0.01mm. Drove 30 miles home and the car felt great with no vibration at all on the old RS5 wavy rotors. I then fitted the new discs and the vibration issues came back again.

This video shows Audi's before and after clips, as well as the new discs dragging in the caliper once per rotation:

So at this point I'm thinking that not only were the hubs out of tolerance, but the new discs are also out of true. The car's off to Storm Developments today for further diagnostics (e.g. checking the drivetrain for any distortion).

Manda, how's your car been since your last update? Still smooth and trouble free I hope!

oh man that sucks, I dont really want to jinx it but so far...
I know someone who had the same issue recuring on his mk4 golf, no explanation, so replaced his disks and that fixed it, but after a few months the symptoms would come back, and it all started after he got a new set of wheels.
So he ditched the wheels and it fixed the vibration and nothing since.

 

[jaygemson]

So glad that yours is still driving nicely, that's great.

Interesting that you mention wheels. The guys at Storm identified my Team Dynamics wheels as being slightly loose fitting on the hubs, with about 0.5mm of play. This despite them being custom made for my car! So that's definitely not good, and I'll be going back to my original 18s shortly.

They also found that the suspension and steering arm bushes are shot, probably as a result of the vibration and the additional power the car's making, so that's allowing movement where there shouldn't be. New suspensions bushes and steering arms will be fitted soon.

Finally, the discs definitely aren't running true. We measured >0.5mm of run out at the edge, versus around 0.1mm on the original RS5 wavy discs (which are already pretty knackered). They are proper 2-piece discs so some float is allowed (around 0.15mm) but what we're seeing is not right so they're going back to Vagbremtechnic to be inspected and either re-built or replaced.

So, progress is being made, and there's hope for the S4 yet!

 

[Meemo]

wow, I dont know how you still have patience left.
I got new wheels I am refurbishing as a weekend project at the moment and will swap over to be sure.
maybe you can have them bored to 73 merc fitment and use spiggot rings to 66.56 to be sure they are snug fitting rather than swapping back?

 

[jaygemson]

Good shout Manda. Quite frankly though, if you place an order for wheels made specifically for your car they should fit properly, right? I'll keep that option in my back pocket though.

 

[Meemo]

you would like to think so, but my experience with car parts recently has been wrong part or broken\faulty parts sent 5 of 7 times... Losing hope
Got a sticking caliper in replacement of a sticky caliper (never using ebay again), faulty disks.. 10 of them! (Mtec.. you suck), then wrong pads, then the right pads (Euro's but we all know they send the wrong part 8 out of 10 times anyway).. it goes on haha
Good luck! If I was you I would prob have them bored and spiggots, especially if you really like these wheels