Quote:
Originally Posted by thumbster
It's a definite no-no to reset the caliper pistons without cracking the bleeders open. Yes, most ABS units have screens, but the moisture that tends to accumulate in the caliper's piston bores will corrode the internals due to the DOT3 brake fluid's hygroscopic properties. Vacuum bleeding the old fluid is cheap insurance against brake system problems.
If your not cutting the rotors, it's a good idea to at least check the rotors for uneven wear and run-out and then, if it's all ok, rough up the rotor surface with some 120 grit sandpaper. This will enable the pads to seat quickly and give you better initial braking performance.
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None of the OEMs feel that it is necessary to open the bleeder when retracting the caliper piston. When Ford was asked this question during the Big 3 Brake Symposium in 2001, they stated that there isn't enough fluid movement in the system for any problems to occur.
For modern day brake pads, smoother is better. OEMs generally want the surface finish to be under 100 microinches. 150 grit sandpaper is a good way to improve the finish quality after resurfacing the rotor on the lathe. IMO, if the runout and thickness variation are not close to perfect, I'd resurface or replace the rotor.