Debate about warped rotors

MrLabGuy · #1 03-12-2008, 05:01 PM

My wifes Chrysler 300C is shuddering when she applies the brakes. She called Chrysler service about the issue and the technician told her that is sounded like the rotors were warped.

I find that hard to believe taking into account the quality metals and designs used in today's rotors. Had the car been designed properly for normal driving the rotors should not warp. My wife has about 32K on this leased 300C which gets turned in September of this year. She commutes a short distance to the next town on the freeway at the most 20 miles.

This is what I feel is most likely happening. The pad material which gets embedded into the rotors has distributed unevenly causing the brakes to grip at different parts of the rotor which created a shutter. This is pretty common with run of the mill pads and the result is the same...Replace the rotors and pads the same as if the rotors were really warped. Unless you are auto crossing or riding your foot on the brakes I doubt you've created enough heat to warp the hardened metals used in todays Heavy Duty brakes. Unless Chrysler used inferior metal in the rotor or under-designed the brakes for her size vehicle which I doubt.

What say you car fanatics?

Quicksilver · #2 03-12-2008, 05:04 PM

I ended up with warped rotors on my 7 series twice. Stopped the shuddering right away.

primetime · #3 03-12-2008, 05:09 PM

Its not unlikely that Chrysler used inferior parts..But it could be any number of things...Furthermore try to see if the rotors can be resurfaced.. They usually can do that sort of thing if its not too bad...

Wagner · #4 03-12-2008, 05:07 PM

I warped a rotor and locked a caliper on the X5

So many things can cause a rotor to warp, poor pads being the most apparent. Is she hard on the brakes?

Wagner · #5 03-12-2008, 05:12 PM

Doubt it has anything to do with product inferiority...if that were the case...my X5's caliper and rotors were POS's considering they were all (rotors) replaced twice in 50K miles. Too much can effect this and cause an otherwise good rotor to go bad.

MrLabGuy · #6 03-12-2008, 05:14 PM

Wow...I was told I had warped rotors on my E39 5 series BMW and I tested out my own theory.

I took the car out and did a series of high speed panic stops in forward and reverse to in a sense redistribute the pad material and the shudder was gone.

My guess is this condition is being called warped rotors because it feels like warping. Unless the rotors are taken off and run against a lathe there is no way to tell. Seeing most rotors today are just replaced and not turned down there is no way of knowing. BTW...It is a good thing not to have rotors turned down. That reduces the thickness and caused the rotors to heat up faster thus reducing the life and braking distance.

I guess it could be warping but that would surprise me considering how she drives this vehicle and the fact that the Hemi comes with gigantic disks up front. Also...I doubt BMW uses undersized or inferior rotors so the fact that this happens brings quality into question.

Quicksilver · #7 03-12-2008, 05:18 PM

One of the things i use to do was backup at a good clip and hit the brakes and that use to move things around just enough to halt it for a while.

MrLabGuy · #8 03-12-2008, 05:46 PM

Quote:

Originally Posted by Quicksilver

One of the things i use to do was backup at a good clip and hit the brakes and that use to move things around just enough to halt it for a while.

That almost makes my point. That alone would not bend your rotors back into place but what it would do is lay down a temporary bed of pad material over the rotor which would make for an even braking surface.

This is why bedding your pads properly after a brake job is so critical. After a fresh install you should not heat up your brakes and then sit at a traffic light or stopped on the freeway which would allow that pad material to penetrate into the rotor in that critical time-frame in that one area.

What I do is find a close parking lot or side road and do a few controlled stops forward and backward to lay down an even bed of pad material. Since I've been doing this I've not had any of the warping issues which were common with my first 5 series and other cars prior.

soccerjunky · #9 03-12-2008, 06:30 PM

Quote:

Originally Posted by MrLabGuy

That almost makes my point. That alone would not bend your rotors back into place but what it would do is lay down a temporary bed of pad material over the rotor which would make for an even braking surface.

This is why bedding your pads properly after a brake job is so critical. After a fresh install you should not heat up your brakes and then sit at a traffic light or stopped on the freeway which would allow that pad material to penetrate into the rotor in that critical time-frame in that one area.

What I do is find a close parking lot or side road and do a few controlled stops forward and backward to lay down an even bed of pad material. Since I've been doing this I've not had any of the warping issues which were common with my first 5 series and other cars prior.

Great advice..i do same thing making sure not to leave my foot on the brake pedal when stationary

1. After installing new brake pads, make 6 to 10 stops from approximately 30-35 mph applying moderate pressure.
2. Make an additional 2 to 3 hard stops from approximately 40 to 45 mph.
3. DO NOT DRAG BRAKES!
4. Allow 15 minutes for brake system to cool down.
5. After step 4 your new pads are ready for use.

i did this with my axxis pads on the x5 and when i stopped they were smoking .... however since they point on they performed flawlessly

motordavid · #10 03-12-2008, 05:18 PM

LabGuy,
Does she or, you notice any steering wheel wobble/shake/wiggle at
any speed, while not braking? Even slight wiggle?

I've had the high speed brake shudder on our X since about the 2nd or
3rd year...stlr blew it off several times. I got new front pads & rotors
under maintenance in year 4: made it feel slightly better for 20 mins.

New, (to me), style 132s with good rubber in year 5: brake shudder gone.
Could not get it to shudder no matter what I did. Year 6, nail in front left
of those 19" 132 tire: hillbilly tar changer did not put tire back on anywhere
near where it was originally mounted, around the circum. of wheel: brake shudder
back immediately.

I've posted this refrain several times here...I have found a very good Indie in Asheville
who went over the front end with a fine tooth comb. His opin was susp. components were fine.

Anecdotally, I think it's a combo of brake pad residue, rotor wear, and tire imbalance due to
tire wear over time. Threads here tell of complete front end R&R with some to no cure. It's a mystery.

I still have an occasional wobble in wheel at speeds from 35-<60 and occasional high speed brake
shudder espc. on long road trips when the brakes are used infrequently, but severely, as in dodging
cops/hard braking for the idiots on the interstates...
Curious to read if your wife's steering wheel has any shimmy, sans braking.
GL,mD