Pdvsa

Hello my fellow audiers,

I have a dilemma. I bought a pre-owned rs5 and the rotors were replaced by previous owner back in dec 2014 (9 mo ago). I have had the RS5 for 2 months and took car in to Audi dealership for possible warped rotors. They did their spec out and my suspicions were accurate: warped rotors (once again). In my short 2 month ownership I have never taken to a track. Since the new rotors were put on, there have been 10k miles put on car.

Audi doesn't want to replace the rotors once again as all 4 were back in dec 2014 under previous owner.

I think the rotors are not of good quality. I have not driven the car hard. I have owned many sports cars and it seems to me that the rotors are of inferior quality.

Audi America will make their decision on Friday in regards to if they will replace.

If they don't, what are your suggestions? Also, I am interested in hearing your stories about Audi rotors.

Thank you

superswiss

There is a lengthy thread, actually several threads, over on Audizine about this issue. I'm not gonna repeat everything, but first and foremost there is no such thing as warped rotors. It takes a tremendous amount of abuse and heat to truly warp a rotor. What you are experiencing is uneven pad deposits and/or lateral rotor runout. Most techs just don't know how to properly diagnose brake issues, so they give you the lazy *** warp rotor diagnosis. The main culprit seems to be soft OE pads. The question to you is, did the previous owner bed the brakes properly? Many of the owners over on Audizine who are experiencing this issue have gone through several rotor and pad replacements under warranty. At some point, Audi supposedly discovered that the rotors were getting damaged during shipment to the factory, so it is possible that your car came with damaged rotors from the factory and the replacement rotors were damaged as well.

I personally had no issues with the OE rotors and pads. They lasted about 24k miles and performed excellently. I drive the car hard. I did European Delivery and put 4000 miles on the car in Europe. Many of those were high speed Autobahn runs and often involved full braking at triple digit speeds due to some moron pulling out in front of me. I also went to the Nurburgring while I was there. I do not buy into the claim that many have made that the rotors and/or pads are weak. That's just not what I personally experienced.

Nonetheless, I decided to go aftermarket and replaced the OE rotors with the ECS full float rotors for better cooling, better thermal expansion and the self centering nature of full float rotors, and I replaced the pads with Hawk HPS pads. I also replaced the brake lines and use race fluid. I'm an avid canyon carver, so I like good brakes and while the OE setup performed fine, I felt they could use a little upgrade. I love the new setup. I subscribe to the notion that a car is only as good as its brakes, so my aftermarket setup definitely noticeably improved the car , however, I wouldn't say the OE setup is bad.

Pdvsa

Hi superswiss, thank you for the response. I want to follow up in regards to the term "warped". The mechanics put the rotors in a runout machine and they measure the trueness and the rotor(s) are not true. If they are not true then to me, it seems its the metal that is not true because that's what the machine measures.

Anyways, I appreciate your comment and link to audizine. Will read in a minute.

Looking for more responses from others...

1stGOAT

I would agree with previous poster. Almost impossible to warp rotors, if really are not true I would bet they were defective before they were put on. If they are warped, you obviously need to replace them. I would check with a vendor like RacingBrake for a 2 piece rotor and something like HPS pads are fine for the street and easy on rotors. If Audi is going to replace them, ask them to check trueness before installation and note the run out measurement.

superswiss

As I said, you have uneven pad deposits or true rotor runout. If you have uneven pad deposits, then your rotors are thicker in some places and thinner in others due to the uneven layer of pad material on the rotors. That would show up as the the rotor being untrue. Uneven pad deposits can be caused by standing on the hot brakes at a traffic stop or by failure to bed them and then the pad material unevenly splotches/smears onto the rotor when get some heat into them. The purpose of bedding high performance brakes is to lay down an even layer of pad material on the rotor. In order to do that you need to get controlled heat into the pads. If the pads don't get heat in them, they work in abrasive mode and basically scrape directly against the metal, which is not what you want. You also have to repeat this process regularly as during daily driving the brakes never get hot enough to maintain this layer of pad material and instead scrape it off the rotors until you are back down to the metal.

True rotor runout on the other hand can be caused by manufacturing defects or damaging the rotor before installation and a very common cause for runout is improper torquing of the wheel bolts.

I agree with 1stGOAT, make sure they check the new rotors before installing them.

SloopJohnB@mac.com

The way to do it is to use a washer stack under each lug bolt rather than the wheel…torque the bolts and then do a runout check on the rotor.

I know of NO dealer tech that is going to do this or check runout on a brake lathe before installation. LOL. They'll install new brake rotors and pads and go for a test drive…smooth braking good to go.

There's no way to check rotor runout except on a brake lathe before installation; and that won't necessarily give you an accurate installed reading..it's really difficult to check rotor runout with wheels installed.

Pdvsa

Hello 1stGOAT (others feel welcome)
Couldn't the rotors be tried on the lathe?

Pdvsa

Thank you for the responses.

General question: could the rotors be trued up on the lathe? I think this might be called "turning" them or at least this is what I have heard it termed as.

I understand from the posts that the pads should be "bedded". I guess this process would apply to my current pads as well or not recommended for old pads.

superswiss

No, you shouldn't turn cross-drilled rotors. Turning weakens the material and the chamfer around the holes and makes the rotor more prone to cracking.

Yes, you can bed your current pads, but if you already have uneven pad deposits, then it won't do much. You would have to run an aggressive pad for a while to scrape off the current deposits and then switch the pads back and do a proper bedding.

Pdvsa

Oh I didn't think about the rotors being cross drilled.
I registered on audizine and have read some of the posts. It's been an education.

I am siding with the idea the pads might need to be stepped up to maybe the hawk HPS 5.0 as some other members recommended these pads.

Hopefully AOA will get the dealer to replace the rotors. Not so sure as the dealer knows the rotors were replaced once already back on dec 2014.

If the issue seems to be with the pads then I would think Audi dealers should educate on this when buying the more high performance cars.