Annoying reoccurring brake wobble - HELP!

Conquistador · #1 5th June 2015, 08:52 AM

Car started getting terrible brake judder when braking on the way home from the annual meet. It became gradually worse until the car was almost undriveable.

Front discs and pads were placed last month by Formula 1, along with one of the uprights (or "hubs" as Audi calls them) at great expense.

Took it straight back there on Monday morning and they agreed to change the pads under their warranty. Got the car back and exactly the same thing is happening, if not worse. It even wobbles slightly when the brakes aren't applied now. F1 said the next step would be to fit genuine Audi pads.

Now, I do remember one of the techs taking me out to the workshop to show me the new discs on the car when they were fitted last month. It was in the air on a lift so the discs were about shoulder height. He put his hand on the driver's side disc thinking it was already bolted on but when he did so, it fell to the workshop floor narrowly missing his foot. Could this have affected anything I wonder?

Or could it be where the new pads weren't bedded in correctly? I'm conscious of holding the brakes on when stopped after braking so the heat from the pads is concentrated to one point on the disc causing warping in the long run but build op of contaminants short term. I usually slowly creep forward in traffic to avoid this now.

Sorry for the long winded post but I want to get to the bottom of this!

DJS · #2 5th June 2015, 09:17 AM

When they changed the pads under warranty did they also change the disc's?

Conquistador · #3 5th June 2015, 09:21 AM

Not the second time. Just replaced the Pagid pads with more Pagid pads.

He also mentioned it could be worn bushes. Don't agree with this though.

Can't drive it above 50mph without getting wobble now

DJS · #4 5th June 2015, 09:26 AM

That will be your problem, with brake judder 99% of the time its the disc's that are warped and the pads get damaged as a result. That's why the judder has come back so soon after the second set of pads. I would ask them to replace the pads and disc's and then bed them in correctly.

ainarssems · #5 5th June 2015, 09:33 AM

Quote:

He also mentioned it could be worn bushes. Don't agree with this though

Could very well be bushes, quite common cause of brake wobble on Audi's under moderate braking. It's usually the bottom curved arm bushes.

David's8 · #6 5th June 2015, 10:00 AM

Quote:

Originally Posted by ainarssems

Could very well be bushes, quite common cause of brake wobble on Audi's under moderate braking. It's usually the bottom curved arm bushes.

As stated above, mine was a combination of factors and, if the bushes in the lower control arms have some play, then that will make any shuddering worse even if it is not the cause of it. That was why even when the new pads/discs had cured 90% of the shuddering, i still some at high speed braking. The issue of warped discs has been discussed before and the likelihood of such an event seems to be considered as low if not unlikely. Unless of course someone has hard, physical evidence of warping occuring? (I am happy to be open minded on this)

David's8 · #7 5th June 2015, 09:26 AM

Mine suffered this issue for while. I had new discs and pads after which the shuddering started. My independent changed the discs under warranty (although I think that warping is a low probability issue) and also found that the new pads from Pagid had cracked. (see my post elsewhere). The shuddering still occurred slightly over 75mph on braking and that was cured by replacing some of the control arms which had a small amount of play. If yours now shudders without braking then it must be balance or alignment.

It may be that dropping the disc has damaged the disc and un-balanced it. Were the wheel weights dislodged when removing/replacing the wheels? Also replacing the hubs would iirc require alignment check.