AMGonFire

starting to wonder if something else is wrong with my wife's front brakes. Changed out the front rotors twice now cause I was getting pulsation and vibration in braking from warped rotors. Each time it fixed it. Pads looked good happened each time after about 8 months. Doesn't seem right. I mean my wife can't possibly be driving that bad. Stock brakes lasted 4 years no pulsation. I went all mb genuine first time. Second set rotors went with brembo. Could my calipers be bad? What do you guys think?

Mmr1

She can't be a bad driver? Have you seen her driving habits? The only time I warped rotors was when I used to take a highway they put up stoplights on. I'd get up to 60 then have to slam on the brakes. This went on for miles. Go, stop, go. I figure as I was stopped the area the pads hit cooled faster and warped the rotors. I changed how I brake and rotors are fine. Now I'll stop easier and creep so the pads are not sitting in one place. If all pads have similar wear , front are equal, rear are equal then it should not be mechanical. But I had a sticking caliper that was nearly locking up. If I didn't notice the excessive dust and that one wheel temp was much higher it would have done damage . I got it fixed under warranty. If fronts wear a lot faster than rear it could be a proportioning valve.

AMGonFire

ill have to compare front to back. I say can't be her driving because we have owned the car for 6 years. The first 4 was fine until I had to change brakes. Went oe. And then the quick warping of rotors started. I'm saying she isn't driving any different then the first 4 years compared to the last 2.

Mmr1

Look for more dust on one wheel and uneven wear on left to right . I had one wheel black, with an IR thermometer it was about 50f hotter than the other one

formerjeepguy

Does she like to use the hold function a lot?

"warped" rotors are most often uneven deposits of braking material on the rotors causing uneven friction and pulsing.

You might look into cryo treated rotors.

AMGonFire

I'll check that thanks

AMGonFire

no she doesn't use the hold feature at all. Never heard of cryo treated rotors where can I get them from

wunderless

Why is that an issue?
What's the difference, say at a red light, between the HOLD function and just standing on the brakes? Isn't hold just a line lock?

Hugo L.

I was about to ask the same thing.

formerjeepguy

I don't *know* that using the hold is an issue. But I have been thinking that when stopped the pedal pressure is usually fairly light leading to lighter pad pressure on the rotor. But you have to press harder to activate the hold thereby creating increased pad pressure on the rotor. When combined with a very hot rotor I think this would also increase the amount of friction material transfer to the rotor exacerbating the pulsing.

The theory is that after a hard stop from highway speed then using the hold you could get thick spots of pad material on the rotors leading to "warped rotor" symptoms.

I don't know this as fact and I was looking for data that might support the theory.

formerjeepguy

Centric, stop-tech and others make cryo-treated rotors. The evidence suggests that slowly cooling the rotors to cryogenic temperatures then slowly heating them and then allowing them to slowly cool to normal temps will stabilize the crystalline structures in the metal. Some studies in fleet vehicles show that this makes the rotors last much longer and makes them much less prone to uneven friction material transfer - "warpage".

Please google it for more info.

Odd Piggy

"formerjeepguy" may have the correct cause of your problem. Floating brake calipers are not very sensitive to actual warping, but all disk brakes are very sensitive to uneven deposits of pad material or small thickness variations in the rotor. 0.0001" micrometers and dial gauges can diagnose the problem, but it is usually less expensive to fix the assumed problem than buying the measurement equipment.

If it is uneven brake deposits, a "re-bedding" procedure may correct it. To do that a long road with very light traffic, like a rural interstate feeder road is needed. Make about 20 semi-stops from 50 down to 20 MPH with medium pad pressure, firm but no panic stops. Between each stop back off the brakes completely for 30 seconds. Do not stop completely. If you must come to a stop, hold the vehicle with the parking brake as holding the brake pedal down will just recreate the original problem because the disks will be quite hot.

If you cannot do this, some higher end brake shops have a motorized drum on which they can do this in the bay.

Benzfooled

My wife's GLK has had warped rotor's as well. First time replaced under warranty at 8,000 miles. Just rear rotors replaced at 23k and the fronts appear to bar warped again.

sethro1980

My rotors started to go around 35,000 miles. I hung in there despite the pulsation when braking and finally got all new rotors/pads at just over 40,000 miles. Go for ceramic pads when you change them out - no brake dust and no difference in stopping power.

Hugo L.

I recently changed my rotors and pads, and used OE pads. Didn't like them, switched to EBC RedStuff, and I now brake a lot harder, and have yet to warp rotors. I don't quite understand how your wife could do that, unless her name is Danica Patrick (in which case pics are welcome).