My 2.0TDi Saloon has a strange vibration/pulsation when I brake from speed eg when coming off a motorway and braking for the roundabout at the junction. It is not the ABS, I know what that feels like. I thought it may be due to wheel imbalance so I had all four tyres re-balanced but it has made no difference. The car is only a little over a year old and I bought it about 4 months ago. Unfortunately I cant quite remember when I first noticed the vibration but now I am aware of it it is bugging me. I could take the car back to the dealer but I suspect they will say it is not covered by the warranty as it is a brake problem and due to 'wear and tear'. Any thoughts?
vibrating saloon
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How often do you drive the car and how do you wash it? If you pressure wash and don't drive it often, it could be rust build up on the discs surface, you can check it visually and see. If it's indeed rust, then doing a couple higher speed shape braking should take care of it.
RichardT
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Brake discs can withstand pretty high heat, for normal driving especially on a year old car, it's hard to get it to warp unless it's exclusively track use?
Brake rust is pretty common on less usage vehicles, the rust formed after washing without driving it through, and the rust spot causes uneven surface on the disc causing the vibration when braking, usually more obvious with high speed braking than lower speed. Again, it's easy to tell if the disc is shinny and clean vs faint rust color spots here and there...
Brake rust is pretty common on less usage vehicles, the rust formed after washing without driving it through, and the rust spot causes uneven surface on the disc causing the vibration when braking, usually more obvious with high speed braking than lower speed. Again, it's easy to tell if the disc is shinny and clean vs faint rust color spots here and there...
Brake disc 'warping' is actually very very (very) rare. What you feel as warping is usually deposits of brake pad material on patches of the disc braking surface. The rapidly changing coefficient of friction is what you then feel as a vibration.
The way to get rid of these is to carry out a couple of consecutive hard stops from 60 to about 10mph. Brake hard, really hard, up to the point where ABS would kick in.
If that fails then a simple pad change can rectify it. A friends fiat coupe used to suffer with this problem incessantly, and he assumed it was warped discs. Replacement brembo discs and OEM were costing him a fortune, but when I did a run-out check on it with a DTI, the discs were perfectly true. I installed some red-stuff pads, gave it an Italian tune-up, and the issue never occurred again
The other common cause of such juddering is tyre damage. Check thoroughly the sidewalls, inside and out, and the tread surface for cracks and bulges.
The way to get rid of these is to carry out a couple of consecutive hard stops from 60 to about 10mph. Brake hard, really hard, up to the point where ABS would kick in.
If that fails then a simple pad change can rectify it. A friends fiat coupe used to suffer with this problem incessantly, and he assumed it was warped discs. Replacement brembo discs and OEM were costing him a fortune, but when I did a run-out check on it with a DTI, the discs were perfectly true. I installed some red-stuff pads, gave it an Italian tune-up, and the issue never occurred again
The other common cause of such juddering is tyre damage. Check thoroughly the sidewalls, inside and out, and the tread surface for cracks and bulges.
I haven't thrashed the car so can't think that I have ever caused the disc temperature to rise to a level to cause warping. The car is used regularly as I do about 20k miles per year and the discs look OK so I dont think it is a build up of rust. I've just had a set of winter tyres fitted and all the wheels balance so I dont think it could be tyre damage.
The mystery continues :-(
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First things first where do you feel the vibration?. Is it through the brake pedal, the steering wheel or the seat?. Hopefully we can then go on & guesstimate on the likely suspects.
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Just to add about new tyres etc...
I had a set of new tyres fitted a couple of years back at a local tyre depot. The car developed a wobble sensation from the rear so I took it back...They re balanced the rears again and the wobble was still there....I had to travel the next day so I told them to leave it till I got back....Well after a very torturous five hour journey I had no option to get it checked out again at an ATS depot in Tewksbury...They checked the wheels and they were shocked to see both wheels were out by 25 grammes on the weights....
When I got home I popped in to my local tyre depot and told them their machine needed re calibrating ....They did get it done and gave me a voucher for £40 as an apology...
So even though new your wheel and tyre combo could be out of balance?
I had a set of new tyres fitted a couple of years back at a local tyre depot. The car developed a wobble sensation from the rear so I took it back...They re balanced the rears again and the wobble was still there....I had to travel the next day so I told them to leave it till I got back....Well after a very torturous five hour journey I had no option to get it checked out again at an ATS depot in Tewksbury...They checked the wheels and they were shocked to see both wheels were out by 25 grammes on the weights....
When I got home I popped in to my local tyre depot and told them their machine needed re calibrating ....They did get it done and gave me a voucher for £40 as an apology...
So even though new your wheel and tyre combo could be out of balance?
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Wheel balance is usually speed related rather than under braking only & you can usually drive through the speed range to induce the vibration to confirm that. If it's felt through the seat & pedal I'd suggest it's worth checking out the rear brakes for warp / corrosion etc & any suspension items also. If the vibration was through the steering wheel it's more likely to be front end.
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It my view it has to be brake related - I would suspect the discs. Easy enough for Audi to check with the right equipment. If the discs, personally, I would insist this was a warranty issue. If (as I assume) you have ATE callipers on the front - their combined calliper retaining/slider bolts are susceptible to baked-on carbonised deposits which can cause slight sticking after applying the brake. These deposits need to be removed with something like wire wool at servicing to ensure continued good performance. The design of the ATE callipers makes this a very easy job to do in situ. without even removing the calliper. I'm sure the apprentices who tend to get the routine servicing jobs do this. 
I have found this sticking to cause both heat build up and uneven wear. If you are doing the equivalent of 20k pa mileage I wouldn't guess that your discs are suffering from rust/lack of use issues.
I have found this sticking to cause both heat build up and uneven wear. If you are doing the equivalent of 20k pa mileage I wouldn't guess that your discs are suffering from rust/lack of use issues.
