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Brake Rotor Warp

Question: What causes Rotor Warp even when the brakes are babied?



My 04 RX has 90K with original brake pads. I’m about to replace the pads and most likely, the rotors. I replaced the rotors @ 48K and now they are beginning to warp SLIGHTLY–but still, my calibrated foot can feel it as I stop. Here’s my question: obviously, from the 90K life of my pads, I’m EASY on the brakes-and purposefully so. I am baffled by the warping rotors. My mechanic always is amazed at my pad life and puzzled by the rotor warp. This has happened to the last 3 vehicles (98 Explorer, 02 Trailblazer, Lexus RX 330).

Where are you driving the vehicle? In the mountains? Heat will warp rotors very fast. Another possibility is overtightening the lugnuts when the tires or brakes are worked on. Lugnuts should be “torqued” and not tightened with a large impact wrench. Thirdly…late model rotors are getting thinner. Thinner means they warp easily even with the best of care or a calibrated foot.

When you replaced the rotors before, did you use good OEM rotors, good aftermarket rotor, or cheap rotors in-stock at your local auto parts store?

One cause is incorrectly tightened lug nuts, My brake guys do a free check after any tire rotation etc.

Often the issue is not “warp” at all but pad deposits on the rotor - those create brake shudder themselves and then the problem just get progressively worse as those spots get to be hot spots (the steel actually gets harder there and it all just goes downhill fast). It is basically an issue of thickness variation in the rotor rather than an actual distortion of the rotor shape.

I have found this discussion to be really useful: http://www.powerbrake.co.za/downloads/tech_01_judder.pdf

It pretty much covers the whole boat.

I read this in a different article a few days ago. At first I was hesitant but there is some validity to this. It claims rotors do not warp at all but build up pad material.

Are you sure the rotors are the problem? Even the slightest wear in a suspension component, steering component, or wheel bearing can mimic a warped rotor.
Warped rotors are not a guess either; it can easily be verified whether or not they are warped or not.

I’ve also read that bunk about rotors not warping and that’s just what it is; pure bunk.
Apparently the people who claim rotors don’t warp are unaware of metal properties, do not own tools like micrometers and dial indicators, and have never considered why brake lathes are manufactured.
Chuck a warped rotor into a lathe and any warpage will be apparent during the start of the first cut.

I would not go so far as to say they don’t warp at all. I’ve experienced clear warpage, and OK4450 posted a phto some time back of a rotor that he’d begun to cut on his brake lathe and they were clearly warped.

But surface deposits can also create problems. Especially if the rotors are not well cleaned of their protective coatings when installed.

Right - the idea wasn’t that they don’t or can’t warp. Just that it probably isn’t the most common cause of brake shudder.