I have owned and worked on dozens of cars over the years, but never come across this. We own a 2008 GMC Acadia. 12 Months/~14K miles ago (at 61K miles) we had the front brake pads replaced and rotors machined. 5 months/6K miles ago (at about 70K miles) we had the rear brake pads replaced and new rotors installed. All done at the dealer.
When we took our car in to the same dealer for a oil change and to look at “pulsing” brakes they told us that all 4 rotors were warped and the front brake pads (with 14k miles on them) were almost worn out and need to be replaced. No change in driving habits. The dealer said that is not abnormal for new brake rotors to warp after 6K miles and for pads to need to be replaced after 14K miles (even though our previous pads lasted over 60K miles.
Has anyone ever heard of this happening before? To me, if all 4 rotors are warped that quickly there is some bigger problem with the braking system where the brakes are being applied, even lightly, all the time. Please let me know your thoughts.
If dealer installed thinner/cheaper aftermarket rotors rather than OEM specific rotors the rotors can warp in a short period of time.
You can read about it here. http://www.aa1car.com/library/raybestos_rotor_warning.pdf
I doubt the rear rotors are bad. If they turned the front rotors, they may have cut them down to much and caused them to warp. I don’t like turning rotors. I actually use Raybestos rotors as mentioned by Tester. As I can attest to by my daughter’s driving, she wears out life time pads out in a year. It all depends on the type of driving and how heavy you are on the brakes. That being said, all the mileages are too low for normal driving.
I agree and would have just replaced the front rotors instead of turning them down. The other thing is I always re-torque the wheels after someone else has tightened up the lug nuts. Over-tightening can warp rotors.
Good input everyone, I can imagine a scenario where they may have used rotors that were cheaper aftermarket ones because there invoice does not state and we were never asked whether we wanted OEM parts. Bad assumption on my part that is what they use.
I could also see the over-tightening too. I always used to re-tighten so I could make sure I could get them off in case of a flat, but this is another good reason to.
My wife’s driving habits haven’t changed that much, so I have a hard time imagining her all of a sudden being 4x harder on the brakes, but stranger things have happened.
My guess was that rotors were machined to thin as knfenimore said.
My daughter who used to drive like a maniac, warped 3 sets of front rotors in 2 1/2 years on a new Nissan Altima. The dealer kept replacing them with new Nissan Pads because that was all that Nissan would use under the warranty. Finally at my suggestion he agreed to try Raybestos rotors.and they lasted the next 112000 miles with no problems.
I guess a mystery still remains, why are the pads wearing out? Because the rotors warp? I just don’t see how warped rotors – unless they were REALLY warped – could cause the pads to wear out. My initial thoughts were that the lug nuts were being overly tightened during wheel install, which is warping the rotors. If you use this shop again, and they remove the replace a wheel, maybe that’s a good time to bring out your torque wrench and see if they put the lug nuts on way too tightly.
hmmmm … Based on what they told you – that is common in their opinion for rotors to warp in 6 K and pads to wear out in 14K – I’d probably seek help elsewhere going forward. In my opinion, other than warranty work on newer cars, and difficult to diagnose drivability problems, it’s better to use a reputable inde mechanic with good references and who works on this make frequently for common repair and maintenance jobs like this.
There’s nothing wrong with machining rotors. Most usually have at least .030 of an inch to work with before reaching minimum thickness and .030 is a lot. If they cut them too thin then that coudl contribute to premature warpage but this should also be easily verifiable by miking the rotors.
Other potential causes of shudders caused by disc brakes could be failure to service the caliper slides while repairing the brakes, sticking caliper piston, failure to thoroughly clean any new or machined rotor before installing it, park brake shoes out of adjustment, etc.
Seeing as you had no problems for the first 60k miles, I’m having a difficult time buying into the 6k miles/now there’s problems scenario as being normal.
I wonder whether the previous pads weren’t bedded in correctly. Procedures vary but on some pads, you have to do careful braking for the first couple of hundred miles.
My Toyota Camry has a SB on warping rotors. It was caused by the OEM pads and Toyota changed the pad composition. Of course mine warped at 50k miles. I installed Ankebono ceramic pads and Raybestos rotors. It brakes great and no brake dust. Ceramic is OEM on the Camry.