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A6 2.7T - Brake Vibrations/Warped Rotors

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Old 05-03-2000, 02:06 PM
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Default A6 2.7T - Brake Vibrations/Warped Rotors

I have experienced brake problems with my 2.7T. The problems occured as I pulled off the dealer's lot when I picked up my new car. It felt like I had warped rotors??? The car was immediatley returned to the dealer and has since had the rotors replaced 2 times. The car now has braking vibrations at high speeds (75mph +). Audi has looked at the car and has determined that it does vibrate, but the vibration only occurs after the brakes are heated up to an unusually high temp. I experianced these problems during normal driving, not unusual or abusive braking. I have an arbitration hearing upcoming with Audi and I was hoping some others may have some advice or can share a similiar experiance with me....Thanks.....Jeff
Old 05-03-2000, 06:10 PM
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Default Re: A6 2.7T - Brake Vibrations/Warped Rotors

Jeff,

There's a well-known problem with the rotors on cars that weren't properly stored during shipment. See item 46-00-02 at the site shown below. Your initial problem sounds like it was probably due to rusting of the rotors, as described in the tech. bulletin.

If your rotors have really been replaced, however, then the remaining problem is puzzling. Occasionally, a brand-new rotor will be enough out of round to cause brake pulsation. (I once had exactly your high-speed-only symptoms with brand-new rotors on my Datsun 510 race car.) Turning the rotors fixes that.

Presumably your dealer is smart enough to torque the lug bolts evenly on each wheel. (Uneven tightening can distort the rotors.) On the other hand, they weren't smart enough to have road-tested your car adequately before delivery...

Other possible causes get pretty esoteric: improperly seated pads; misaligned brake caliper; sticky caliper piston.

A slightly warped (or rusted) rotor still sounds like the most likely culprit--but these things are easy to check. Have they used a dial indicator to check the runout of each rotor?

Good luck, and let us know what happens.<ul><li><a href="http://tech.vw.com/audi/newtech.htm">http://tech.vw.com/audi/newtech.htm</a</li></ul>
Old 05-03-2000, 06:23 PM
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Default Re: A6 2.7T - Brake Vibrations/Warped Rotors

I have the same problem on our A6 Avant... Dealer insists nothing is wrong.. The rotors looked very rusty upon delivery... It is a nuisance, and annoying to feel that vibration while braking.. I think it also affects the braking capability in a negative way...
Old 05-03-2000, 08:50 PM
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Default Re: A6 2.7T - Brake Vibrations/Warped Rotors

The chances of your rotors warping three times is so slight as to be not worth considering. I have an A6 2.7t that I took to a driving school. We took turns accelerating to 60 mph then applying the brakes as hard as we could until the car stopped. After doing this exercise probably ten times in a row, the brakes were so hot that you could smell them smoking but not one Audi owner out of the 30 or so there had any problem with their rotors warping.

I have a TR8 that had a similar problem. I had the rotors turned twice with no improvement. At slow speeds I could feel the brakes pulling harder at certain points in the rotation of the wheel. Apparently the rotor itself was straight but the hub was either bent or improperly machined. By the way the fix was to replace the suspension bushings with polyurethane. It seems that the soft bushings combined with the slight wobble of the rotors caused the wheels to pull side to side, I could feel it in the steering wheel.

My guess on the Audi would be, in this order; out of balance wheel, the dealer never actually turned or replaced the rotors, one or more tires are out of round, one or more wheels are bent or out of round, improperly machined hub.
Old 05-04-2000, 05:28 AM
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Default Does the vibration only occur during braking?...

If not the problem may be else where.

Have you tried rotating the tires/wheels front to back?

The reason I say this is because I had simalar symptoms on another car. It turned out to be a defective tire that could NOT maintain it's balance. The tire would spin balance properly but after the tires warmed up the balance would be all out of wack on the defective tire. If the problem gets better or worse when you rotate the tires, you may have an out of balance/defective tire or a bent/defective wheel. As mentioned earlier by others, be sure that the lugs are torqued properly.

BTW-the culprit tire was a brand new Dunlap SP9000. Once the tire was replaced the problem was gone.
Old 05-04-2000, 07:22 AM
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Default Re: Does the vibration only occur during braking?...

Yes...Only during braking, otherwise there is no vibrations at all......
Old 05-04-2000, 08:22 AM
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Then disregard my previous post. It's probably not the tires/wheels. Hope I didn't waste your time.
Old 05-04-2000, 10:01 AM
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Default Re: A6 2.7T - Brake Vibrations/Warped Rotors

I had a similar problem after about 1500 miles on my 2000 2.7T. The car sat in my garage over a weekend after a rainstorm, so the rotors were wet when the car was parked. The rotors were so frozen to the pads that there was a very loud clunk and obvious jolt when I let out the clutch. This was not a gradual process. The brakes immediately vibrated at all speeds very noticeably. It appeared to be the rear(s) as there was no steering wheel shimmy on braking. Dealer turned 4 rotors, and said pad sticking was "normal". I complained that I didn't want turned rotors on a car with 1500 miles on it and they replaced all the rotors. So far no more rotor warp, but the pads still stick when wet and left overnight. I think it is just a matter of time befoe I have the right combination of wet and a long parked spell.

Incidentally, the dealer tried to tell me the rotors aren't really warped, as the floating calipers compensate for warp and don't cause the vibration we all attribute to a warped rotor. He said the problem was inconsistent surface thickness. So no solution here, just confirmation of the problem.
Old 05-05-2000, 03:49 AM
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Default Re: A6 2.7T - Brake Vibrations/Warped Rotors

Thanks for the message. During my process of trying to get my brakes fixed I have learned some unsettling facts about this car. The dealer admits that when the car sits for an extened period of time without being driven (2-3 weeks), there is a strong possibility that rust will build on the pads. Not unusual on most cars, but they say that the part of the rotor covered by the caliper will not rust therefore causing uneven rusting on the rotor. If the rust builds up too much, the brakes will vibrate and feel "warped" and need to be resurfaced of replaced.....Nice Huh???? $45000 for a car and you can't go away on vacation!!!!
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