Need help: Rotors warping

[youngturk]

If anyone has any experience with this or knowledge of how to fix this problem I would greatly appreciate your help.

I have a '92 240SX SE Coupe with Z32 calipers and 30 mm rotors. My car has the SE 7-spoke 15" alloy wheels with a 15 mm H&R (hub-centric) spacer to accomodate the Z32 calipers. I live in Austin, Texas.

Last year in July, we installed the Z32 calipers with 30mm Brembo cross-drilled and slotted rotors and Project Mu brake pads. The set up worked great, but the rotors warped after a few thousand miles. I had the rotors cut, but they wapred after a few hundred miles. I had the rotors cut again, and they warped within a day. Please note that I am the original owner of this car and really do not drive or brake it aggressively.

A close friend has an S14 with Z32 brakes and S14 stock wheels using Bendix brake pads. I thought the problem with my car was the Project Mu brake pads (which braked very good, by the way) and perhap using cross-drilled and slotted rotors. So, I switched to Nissan OEM Z32 blank rotors and Bendix brake pads. Drove on a high-speed and twisty drive for 275 miles in February '05 (cool weather) with no warpage. A couple weeks after the drive, the weather warmed up about 10 degrees (spring weather). Shortly thereafter, after just regular city driving, the rotors started showing signs of warpage.

Well, with brand new OEM rotors and Bendix pads, I have begun to wonder whether the problem is my wheels. With 15" wheels, the Z32 calipers and rotors are very nicely tucked in there. It actually looks pretty nice. There is very little gap between the top of the calipers and the inside wheel surface. I am wondering whether the design of the wheel is not allowing enough air to the rotors for it to cool off during regular city driving, which obviously does not involve high speeds, but frequent stop and go. I am also wondering whether the small gap between the top of the calipers and the inside of the wheel is causing the heat from the rotors to be trapped.

Does anyone have any experience with or recommendations about this situation? Do I need to get bigger wheels (which I can't afford right now)? Could the calipers be the problem?

Thank you in advance.

[deezlins]

here is a good link about warped rotors and pad material transfer and break inhttp://www.stoptech.com/whitep...h.htm

[sleepyRPS13]

doesnt bad bearings or improper torque of the wheels can cause brake warpage..

[Q45tech]

Or an out of spec hub surface which forces the true rotor to become warped to conform with hub mating surface when rotor heats up.

Use "brakealign rotor shims" to make sure as installed rotors is way under 0.001" to start.

http://www.brakealign.com/pages/products.htm

[youngturk]

here is a good link about warped rotors and pad material transfer and break inhttp://www.stoptech.com/whitep...h.htm

That is a really good article. Helped me understand what things may be wrong. Thanks.

[youngturk]

doesnt bad bearings or improper torque of the wheels can cause brake warpage..

Yes, you are right on both counts. I have already had the bearings tested - they are okay. The problem with improper torque is covered in another NICO posting. I am going to rectify that too.

Thanks for your input.

[deezlins]

you're quite welcome

let us know what you end up finding out