"Warped rotors" - Let's have a discussion

[PatDTN]

Don't forget the effects of worn wheel bearings. I stand with believers of material transfer. I raced a BMW and never had a problem. However I drove my street cars with the same braking style and got horrible brake shudder. My wife was about to kill me when I drove her car and it started it.

On my '96 Buick Roadmaster which accelerates nicely I went out on an empty road and went through a harsh bedding until my brakes cooked. No more shudder. For a while. I finally fixed my driving style, bedded them again and it's nearly gone for good. I think all that hard bedding messed with the metal.

On my '01 Sierra I decided to use metal conditioning pads to clean the front rotors. I was amazed at how much stuff I removed before I was seeing clean metal. That fixed them. Oh, I did use the conditioning pads quickly over the brake pads too.

If you have run pads down to metal on metal all bets are off. Turning rotors will clean the material off.

 

[dross99_si]

Thanks for the contribution!
You're right, other factors such as worn wheel bearings and suspension components may come into play.

 

[the blur]

That is correct. There is no warpage per say. It's just built up pad material that transferred to the rotor. Cutting rotors depends on the cutter, and the machine. Usually it's cheaper to replace them. On our trucks, rear rotors tend to rust, and pad contact seems to get weird. New rotors are cheap enough.

The most important thing on our trucks, is to grease the slide pins. Once the slide pins seize up, pedal travel increases.

 

[Brian Wilson]

For what it's worth, I always try to take top knot ch care of my cars. I always torque in a cross pattern and to spec no matter what. And I used to have problems with every set of rotor I bought and blamed the rotors for being cheap Chinese crap and warped right out of the box. I decided to test this so I bought brand new Chinese drilled and slotted rotors(the kind that have the worst rep for warping) and threw them on a lathe straight out of the box and put a dial on it. What do you know! Warped! Just slightly. I took them back to the parts store and they said I ruined them so no return. Fine. I decided to test them so without cutting them on the lathe I installed them on the front of my 96 zj. Slight shake. Barely noticed it. It may have even been in my head. I decided to do a extremely harsh break in cycle. I wanted to get them as hot as possible and keep them turning. So I take a road trip and get those things hot as hell. All highway. Getting to 100 and braking hard. Repeat. Then used them as little as possible on my way home to let them cool off before parking. I pulled them off a day or so later and put them back on the lathe. Perfectly straight. Absolutely perfect.

Since then, if I have a slight brake shudder I just do the same rough hard break in procedure and then clean the pads with some 240 gritty sand paper. And hit the rotors lightly. I have never bought a new rotor since and I know my old warped rotors are better than the new ones that people are pulling out of the box at parts stores. Just change your pads on time and they will last almost forever.

 

[Brian Wilson]

In short, I think(and proved on several occasions) you can save a warped rotor by getting it hot and letting it cool evenly. When you park a car with hot rotors, your pads are nothing more than giant heat insulators. This causes the rotor too cool faster everywhere except the pad area. This in my opinion is the main source of warped rotors. I have bought the 200$ ebay drilled and slotted rotor kits and find them to be just as good or better than the best parts store or dealer replacements. It is all about breaking them in and letting them cool. If you are towing a tank down hill, don't stop for lunch while your rotors are cherry red. Unhook the tank and let them cool off while you drive.