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Brake rotor cooling


mnichols

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I have a 95 M3 that I run at DE events almost exclusively. Its no longer a street machine. It weighs about 2750lbs empty and as my speed has steadily progressed, so have my brake temperatures. I've wanted to continue using OEM Zimmerman or Brembo rotors with Hawk DTC60 or similar PFC pads. This combination seems to work great on the track, no brake fade and excellent stopping power. However, I've overheated my rotors and warped the passenger side rotor at the last event. I had hoped that it was simply deposits, but alas no. The rotor runout is .004 of an inch, more than double OEM standards. The driver side survived and remains within specs.

 

My car still has the dust shields installed and my next move would be to remove them to get more air flowing around the rotor. Any one have concerns with this idea?

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  • 1 month later...

For what it's worth, I had problems on a WRX with brakes overheating. I perforated the stock dust shields in about a 3" diameter area (a bunch of small holes drilled). I fabricated half-assed ducts out of household ducting; basically a short tube with a couple of flanges. These ducts attached to the dust shield, positioning the opening over the drilled holes. Then I used high temp silicone flex tube, attached to the duct and ran them forward to inlets in the bumper. It was a cheap solution (except for the flex tube) and worked like charm.

 

It would have been much cleaner and easier to use short pieces of 3" od exhaust tubing for the ducts. Before you ask, I don't have pics. Sold the car a few years ago.

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Sounds like it may be time to rebuild your calipers...warped rotors are often caused by frozen/stiff calipers...

 

and add brake ducting

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I'm not too sure about the dust shield design on your BMW, but removing the dust shields on my car had a profound effect. There really isn't a downside to driving without them either. I would start with that if your budget is a concern. If the problem persists then look into making your own ducting or purchasing a kit like the one suggested above.

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  • 1 month later...

I would keep this in mind if you decide to add any type of ducting to the rotor. Make sure the duct blows air into the center of the rotor to the fins, if the duct blows air on the inside pad face of the rotor the inside of the rotor face cools faster than the outside face which will crack a rotor every time.

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