audibot

I had my car into an dealership a couple months ago and when they looked over the car they said the front rotors were warped, but the pads still had about 60% life in them. Then they tell me that I should always replace the pads and rotors together and that Audi rotors shouldn't be turned, only ever replaced. Is there any truth to either of these things or are they just trying to part me and my money?

1move

iTrader: (1)

Whenever replacing the rotors you should replace the brake pads as well. As your current brake pads are grooved to the existing rotor and will cause vibration until it wears down on the new rotor which might cause uneven wear on the new rotors.

jfo

Why do they think they are "warped" and why do they want to replace them? Are you experiencing any symptoms like a pulsing/judder sensation in the peddle as you come to a stop?
If the rotors are not damaged and you don't have any annoying pulsing, then I would ask the SA why they need to be replaced.

StopTech, who produce performance brake parts, wrote an interesting paper on the myth of warped rotors. They determined that the pulsing sensation described as a warped rotor, is actually caused by uneven transfer of pad material to the discs. Here's the paper...

-Warped- Brake Disc and Other Myths

audibot

Thank you to you both for the information. I had no idea that they should be replaced at the same time.

jfo: I am getting a pulsing during braking and it is only getting worse. That article is an interesting read, but could so many mechanics be misinformed/ignorant regarding warped rotors?

If you both don't mind giving me your thoughts on my current situation I would be greatly appreciative.

When I moved to Vancouver in 2011 I took my car to an independent Audi specialist near my work to have my out of province inspection. I was told that I needed new front and rear pads, new front rotors, and to machine the rears. Car had 75,000km on it at the time. I knew of no other mechanics in my area and I didn't want to pay for a second out of province inspection later on, so I told them to go ahead with the maintenance.

Fast forward 1yr and car then has 94,000km. Get a pulsing sensation during braking and they recommend machining front and rears. I get them to do it.

4 months later pulsing is back. This time they tell me the front upper and rear control arms need replacing and that was causing the rotors to move under braking and caused warping. They machine fronts again. Car has 100,000km at this point.

Car now has 106,000km on it and fairly severe pulsing. I will be calling Shift Autosports soon to see if I can get my car in. I see lots of people recommending the shop, so probably can't go wrong. Do you guys recommend sticking OEM or using aftermarket? Car never sees track or hard driving.

1move

iTrader: (1)

I would do the control arms and do an alignment. Sounds like this place did their job but the control arms were going out to lunch. As far as rotors if you are looking for better ones and going with performance i would go with adam's rotors | custom brake rotors, made-to-order and some higher end pads. I personally would run this setup but its up to you. I would definitely change the OEM pads!

jfo

The idea of warped rotors has been around for many years. I've never met or read about a mechanic though, that has actually ever attempted to measure or confirm actual warping. Nor have I ever seen any analysis or recommendations from rotor manufacturers about how to avoid warping. Could it happen? Perhaps, but the StopTech paper is the first and only technical analysis I've ever seen.
I do my own repairs and have replaced many sets of rotors and pads on a number of vehicles over the years. My Audi is 2011 so I haven't had to change them yet. I will likely use Akebono ceramic pads which I've used on other cars and either Zimmerman or Brembo rotors. I haven't experienced pulsing since 1998 on an S70 Volvo, when I first learned about properly bedding in new pads and rotors.
The current OEM pads are fine, with good bite, quiet and improved/lower dust.
You can replace pads without doing rotors if they are in good shape...no runout, but new pads should accompany new rotors.
In Canada, Audi parts are way over priced which is the main reason to avoid them! I usually order my parts from FCP Euro. For Audi OEM, I use AudiUSAParts.com which is an Audi dealer in Portland. Here's one example of local price gouging..I had sticky rear caliper replaced under warranty last month. The part was $800!! The same part at AudiUSA was list of $650, and they sold for $450. Shipping by USPS would have been about $25.
If you need control arms, then they should be replaced. However, I've never heard any connection between worn control arms and rotors. He could be just speculating and you may want to have an Audi tech check them out. If you do need them, I'd look at AudiUSA for pricing and have an indie shop do them.

1move

iTrader: (1)

I agree with this and I don’t think you were trying to nit-pick at me but I was talking about vibrations and pulsating from misalignment or control arms themselves causing the vibration making it more noticeable at breaking as pressure is applied.

jfo

I was just referring to the mechanic's comment about worn control arms causing warped rotors.

audibot

Update: I ended up taking my car to Shift Autosport. No conclusive answer on what the problem was, but they put new front rotors and pads on and no more issues. They recommended Zimmerman rotors and techstar (??) pads. Overall I am happy with Shift's work and their service. If anyone is looking for a new Audi shop, I would give them a try.