"Warped" Rotors

[Ohmess]

So, Sister in law is here for a visit and upon arrival expressed concern that she has "warped" rotors. Vehicle is a 2019 Volvo XC60 with 23k miles.

Vibration does not occur without braking, or when braking from 35mph or less. I strongly suspect the rotors are not warped, but instead have uneven pad deposition on them.

She just had the tires rotated, so I retorqued the wheels. Still vibrates when braking from speeds above 35 mph. So, this is not the problem.

I've always gone through the process of bedding in my rotors with my BMWs, and have never had this problem.

If I had a set of racing pads laying around that fit her car, I might try that. But I don't.

So, my question is, can a bedding in procedure resolve this problem? or is some process of scuffing the rotors required?

 

[HB Chris]

How about the common problem in later BMWs like the e39 with the tension arm/bushing?

 

[adawil2002]

Check tire pressures, mismatched front pressures will cause pulsing. Out of balance wheels will cause this too. May need to have the car aligned if correct tire pressures don't cure it. Examine the treads wear for cupping or uneven wear. How hard is the braking from 35 to 0? Could it be the ABS module is malfunctioning.

 

[autokunst]

I'm on my second set of rotors on my e90. The originals started vibrating, and we cut them. They started vibrating again, and we replaced them. It was subtle, but I am a stickler for this. After a couple of years this last set is holding up so far. Evidently I am hard on brakes. I like corners.

 

[JFENG]

can a bedding in procedure resolve this problem? or is some process of scuffing the rotors required?

I would do a very light cut at a brake shop and then folllw a careful bedding in process. It if comes back, it’s an incompatibility of the driving style and brake compound.

 

[bavbob]

Ask if any potholes or curbs were struck. Sadly, only upon prompting, do my family members recall such things.

 

[mulberryworks]

I've had a couple of Volvo 940 wagons and warped rotors were/are definitely a thing with Volvos. Over torquing or unevenly torquing the lugs is said cause this probably in conjunction with engineering that doesn't allow for real world sloppiness.
I've read on the forums that having them turned is a waste of time and the answer is to replace them. They are not expensive but for one of my cars the pulsing wasn't severe and so I carefully set the torque correctly and the pulsing gradually subsided over a few months though I sold the car before it went away. YMMV.

 

[teahead]

THey're warped.

Pads should have been bedded by now.

 

[Sean Haas]

My wife's Subaru used to have this occur commonly. My guess is a combo of crappy pad material and hard stops holding the pads in pace while hot. In any event I would just essentially rebed them, and some partial stops from high speed on an exit ramp would redeposit pad material evenly and eliminate the vibration. Has worked with some other cars as well. Worth a shot, don't cost nuthin'.

 

[Stevehose]

My F150 rotors would warp very quickly

 

[tochi]

So, Sister in law is here for a visit and upon arrival expressed concern that she has "warped" rotors. Vehicle is a 2019 Volvo XC60 with 23k miles.

Vibration does not occur without braking, or when braking from 35mph or less. I strongly suspect the rotors are not warped, but instead have uneven pad deposition on them.

She just had the tires rotated, so I retorqued the wheels. Still vibrates when braking from speeds above 35 mph. So, this is not the problem.

I've always gone through the process of bedding in my rotors with my BMWs, and have never had this problem.

If I had a set of racing pads laying around that fit her car, I might try that. But I don't.

So, my question is, can a bedding in procedure resolve this problem? or is some process of scuffing the rotors required?

As discussed in this thread, there could be many causes of vibrations when braking. (E.g., loose wheels, loose calipers, loose pads, loose/worn wheel bearings). Easiest and most direct approach might be pulling the wheel and inspect rotor condition including a check for runout while rotating. For those with dubious eyesight, a dial indicator worth employing.

Bedding in process probably would not have any effect on already-glazed pads. it might offer some benefit with freshly scuffed rotors and friction material. As an aside, I don't think any rotors, including those originally fitted to E9s are completely immune from warping or even even cracking. This is especially true when hot brake parts meet not unforeseen conditions like sprinklers puddles and weather anomalies. A friend recently rotated the tires on his all original E3 and was surprised to find one of his front rotors was cracked. This was despite the fact that his vehicle never exhibited any symptoms.

 

[Sean Haas]

THE REAL TRUTH ABOUT WARPED BRAKE ROTORS

The REAL truth about warped brake rotors... The typical situation: New pads are fitted to a new pair of brake discs. A week later there’s a vibration or “judder” when the brakes are applied. A call to a mechanically inclined friend and an online search offers the diagnosis—the brake rotors are...

alconkits.com

Not always the case, but an interesting discussion about why vibration may occur without an actual warp, which was generally my case.

 

[Blinkling]

My '93 Taurus had this problem constantly. Getting rid of the original brake calipers which had stationary caliper pins helped. Then, switching to 2-piston calipers from a later Mustang solved the rest of the problem.

My theory is that on crappy systems: the pads shift around; and the piston goes off-axis and binds a bit; and the leading edge of the pad heats up more than the back edge; the pad material gets deposited willy-nilly all over the disk.

I kind of think that for some cars you've just gotta replace the caliper, rotor, and pad at the same time. Sadly.