Warped rotors-what's the deal on the family cars?

[Oh Haha]

Our Grand Caravan has 43,000 miles(we bought it with 36,500). While we were in the UP the brakes started shuddering with application.

My wife drives the van to work, about 400 miles a week but I was driving during our vacation. It was very noticeable on a freeway offramp, slowing down gradually from 70 MPH.

I pulled the front rotors today and had them turned and it's back to normal.

My question is what causes the rotors to warp? I know that hard use like on the track can certainly be a cause but what about the family truckster?

When I come to a stop after gradual slowing I will release the brake pedal for a moment and then gently hold the vehicle still. My thought is to not "melt" the pads into the rotor in one spot. I do this with every vehicle I drive including my work trucks, with and without air brakes.

What is the general thought on warpage?

BTW-my sister has the same problem in that she only gets around 10,000 or so miles on a set of rotors. Is it the driving style of the gals?

[red-beard]

I find that warping seems to be casued from PARKING the car not long after heavy breaking.

The rotors heat up but, the pads prevent that spot from cooling down and while the rest cools, when parked. I had this happen on the Grapevine going north. We stopped at the rest area about 3/4's the way down towards Bakersfield. I had to go into Bakersfield and find someone who could turn the rotors. This was with my parents fully loaded Explorer.

[enzo1]

On my toyota 02 sequoia, I felt it was because the brakes were too small necessitating that my WIFES driving habits ( TOO FAST) applying brakes in a abnormal fashion, LOL toyota fixed the problem with bigger and better quality system

[Eric Coffey]

Originally Posted by Oh Haha

My question is what causes the rotors to warp?

Sounds like bad engineering/design.

[masraum]

I think that most cars have undersized brakes (at least compared to a sports car, and they do seem to be getting better than 20-30 years ago). Because they are undersized, I believe they are more susceptible to heat and more aggressive driving.

The specifics are probably what James mentioned.

I've heard/read that parking with hot brakes can lead to pad material or glazed deposits sitting on the rotor faces which cause the pulsating (not actually warped like an old record) rotors which again, is inline with what Red said.

[Rot 911]

Originally Posted by Eric Coffey

Sounds like bad engineering/design.

This. The 1999-2000 Jeep Grand Cherokees were notorious for this. Defective rotors. Went bad after around 20K miles. No recall, but they would fix them under warranty.

[legion]

Unless you can physically feel the brake pedal pulsating, it's usually not warping. Usually, it is simply oxidation built up on one part of the rotor but not another part. This can be caused by washing your car on the driveway (the calipers protect part of the rotor) or having the car parked in the rain.

This happens to my wife's car every single time it rains and she has it parked at work. The solution? Taking the car out into the country, winding it up to 70, and applying the brakes firmly until it comes to a complete stop. (Basically re-bedding the pads.) It wipes the oxidation right off of the rotors.

[red-beard]

Originally Posted by Rot 911

This. The 1999-2000 Jeep Grand Cherokees were notorious for this. Defective rotors. Went bad after around 20K miles. No recall, but they would fix them under warranty.

I wish I'd known this, because my Cherokee seemed to warp rotors anytime I did any towing.

[masraum]

Originally Posted by legion

Unless you can physically feel the brake pedal pulsating, it's usually not warping. Usually, it is simply oxidation built up on one part of the rotor but not another part. This can be caused by washing your car on the driveway (the calipers protect part of the rotor) or having the car parked in the rain.

This happens to my wife's car every single time it rains and she has it parked at work. The solution? Taking the car out into the country, winding it up to 70, and applying the brakes firmly until it comes to a complete stop. (Basically re-bedding the pads.) It wipes the oxidation right off of the rotors.

I've seen rusty rotors after a good rain or a wash, but that's usually done after a stop or two. I've never noticed it cause what anyone would call pulsating.

[Oh Haha]

The pulsating was most definately felt in the brake pedal. It may have been slightly for a while but she didn't notice it. I really don't drive it unless we are going away with the kids.

I thought maybe it was the way she drives but her response was to repeat my mantra about not keeping the rotor/pad in one spot after a long stop"just like you told me". Ok fine, so you were actually listening to me.


BTW-the pads looked good but I scuffed them and then took the vehicle out and bedded them to the rotors.

[A930Rocket]

I had 120k miles on my 01 F150 truck with original rotors before I had them replaced for grins. Since then and the past 60k highway miles, I've replaced the front 3 times and turned them twice because of warping. The last set were factory Motorcraft rotors, but were made in China and I think thus is the crux of the problem. Cheap metal and cheap parts, even if they are factory.

I wish I had my original rotors. They'd probably still be good.

[GWN7]

On my 98 Chev the rotors warped shorty after I had new tires installed. My local wrench asked if the tire shop used a impact gun on the aluminum rims. Over torquing the lug bolts can warp the rotors acording to him. Ever since I've followed the mfgs specs of 95 ft lbs and no problems.

[Tobra]

^what Bruce said^

[onewhippedpuppy]

Ditto on poor design and cheap parts. It seems even more prevalent when using aftermarket replacement parts. Land Cruisers like mine are known for being tough on brakes, but supposedly they very quickly destroy non-OEM replacement rotors. You get what you pay for I suppose.

[kanadary]

i have heard that if you put cold water on a very hot brake you can warp it too. ie. washing the car right away.

[MotoSook]

Under or marginal design and cheap castings used for replacement.

My current case: BMW 530i.

Bought STOPTECH slotted rotors for all four corners. As soon as I bedded in the new pads, STOPTECH street performance pads, I developed a vibration in the front. I thought I just over did it and it would smooth out, but it never did. I checked runout and it verified warped rotors. Had them turned and rebedded with less enthusiasm. A month later more vibration. Now the steering wheel vibrates so much it's embarrassing.


This is a case of well a designed system with poor replacement part quality.

Had problems with the Jeep Cherokee too. Poor quality rotors from FLAPS. I replaced them with Zimmermans IIRC and it fixed the problem. Fortunately, Jeep rotors are cheap. Not so the BMW rotors.

Unless you are descending a grade and/or really heating the brakes towing w/o trailer brakes, I really don't think some of the suggestions about pad deposit on a hot rotor or warping due to heat insulation by the pad are a concern. Most street driving won't generate that much heat.

Another potential problem is rusted or sticking caliper carriers or calipers. This is particularly so with single piston caliper designs that allow the caliper to float on pins (inboard side only). If you've changed enough pads you'll have noticed that the pads don't wear evenly on both sides. This tells me the pads don't work evenly and those could generate heat at different rates on each side of the rotor. It also could result in unequal force at moments.

We're all so used to opposing pistons on our Porsche calipers.

[berettafan]

Thought the Jeeps got totally redesigned front brakes around that time? Seems to me our '01 had that done at some point. under warranty as well.

[MotoSook]

When I tried to get the dealer to replace my rotors on the 2001 Cherokee. They said the poor design was only on the larger Grand Cherokee. I don't know why I didn't press the issue as I was still under warranty IIRC. Probably 'cause dropping off the car or waiting at the dealership was more a PITA and a waste of my time than what a pair of rotors are worth. I hate dealerships. Even when they do the work under warranty they is always something not to my liking. No matter the reputation of the dealership, there is always some inept service writer or incompetent tech all trying to milk job for more money.

[TechnoViking]

Originally Posted by legion

Unless you can physically feel the brake pedal pulsating, it's usually not warping. Usually, it is simply oxidation built up on one part of the rotor but not another part. This can be caused by washing your car on the driveway (the calipers protect part of the rotor) or having the car parked in the rain.

This happens to my wife's car every single time it rains and she has it parked at work. The solution? Taking the car out into the country, winding it up to 70, and applying the brakes firmly until it comes to a complete stop. (Basically re-bedding the pads.) It wipes the oxidation right off of the rotors.

This is true. It is very tough to warp rotors, or at least it should be. The feeling of unsteady gripping of the brakes can be caused by brake pad deposition on the rotors. When the rotors get hot, then you sit at a stop light with your foot on the brakes, a thin layer of the pads can chemically bond to the surface of the rotors, giving you the feeling that they are warped.

In my experience, the brake pad deposits can be very tough to get off, and turning the rotors may be necessary. So the fix is the same, but I bring it up to point out that going with a cheap brake pad can cause the problems you guys are talking about.

[Talewinds]

Originally Posted by Rot 911

This. The 1999-2000 Jeep Grand Cherokees were notorious for this. Defective rotors. Went bad after around 20K miles. No recall, but they would fix them under warranty.

I have a 2002 Grand Cherokee that experienced the problem very badly on its first set of brakes. I replaced them w/ slightly better equipment after that and in 204,000 miles I think I've only replaced the fronts 3-4 times, but it's shuddering again and I can tell its time for front brakes.

The conversations I had about the issue is summed up like this; The Jeep is 4,400lbs (actually quite light for SUV's, so consider the ones weighing 6,000lbs!), compare the brakes to those of your old Carrera and you'll instantly see the issue, the brakes are the same size (possibly with less overall mass) than a car half its size. PLUS, every commuter drives whatever vehicle they have these days like Mario Freaking Andretti.
To save weight/material, our obese SUV's and trucks get OEM brakes with not nearly enough mass and the vehicles are then driven quite aggressively compared to the way a pickem'up truck is designed to be driven.