Thread: Disc brake drag
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Old 06-28-2011, 09:34 PM   #42 (permalink)
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Mercedes even has service bulletins for the parts department on how to store brake rotors to keep them from warping before they were installed as replacements.

The previous post is precisely correct, concerning newer calipers and their ability to retract the pads a few thousandths to minimise drag. It does require rotors to be smooth and true to work properly. It will still work with worn-warped rotors but nowhere near as well. We turned every rotor before installation to make sure things started out with everything smooth. I have returned new rotors that were warped 40 thousandths right out of the box. possibly the improper storage MB had warned us of decades earlier.

On my 94 VX the brake fluid was so bad after sitting for 15 years the rubber under the cap on the master cylinder reservoir had basically disintegrated. Change the fluid as previously recommended, but I have some more suggestions based on experience.

If your car is over 10 years old, you may loose the master cylinder if you pressure bleed and push the pedal to the floor. It is better to flush the system while not pushing the pedal any further than its normal travel. If you suspect dragging or sticking calipers then you can diagnose things fairly quickly with a digital thermometer (also useful for a lot of other diagnostic procedures). Do a test drive and just read the temp at each wheel. If one is much hotter or colder than the others then you can safely assume the issue lies there.

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