From digest.v7.n304 Fri Sep 19 16:00:30 1997
From: MARKSFAVA_at_aol.com
Date: Fri, 19 Sep 1997 16:25:09 -0400 (EDT)
Subject: RE: <E30> Brake Rotors

Dave,
In my opinion, it's not worth it to resurface rotors. If the rotor is warped, which yours are not, the warp may be "removed" by resurfacing but would probably soon return with the first hard stop. Apparently, the metal undergoes some transformation during the initial warping process that leaves it prone to re-warping.

It sounds as if you son's rotors are not warped but mererly have some surface grooves. I'd take them to a reputable parts store and have the thickness of each rotor measured; there is a minimally allowable thickness. It may be stamped on the rotor; if not, the parts store should have a listing for the minimal thickness. If the rotor(s) are close, replace them in pairs - both front and/or both rear rotors.

Now, I have my flame suit on - buy the new rotors at the dealer! You'll find them cheaper via mailorder but BMW OEM quality is tough to beat. I know - I've ordered parts that were supposedly "OEM" and turned out to be junk! Flame suit off.

If the rotors are well within spec, just remount them; the groves won't affect braking performance. Do replace the socket head screw that holds the rotor to the wheel bearing flange. Buy them at the dealer too Use anti-sieze compound on the threads of these screws. Also, use lithium grease on the hubs - where the center of the wheel mates with the hub. Since BMW wheels are "hub centric," it's a very snug fit between the wheel and the hub. Corrosion, however minor, will make the removal of the wheel a real bear.

Pads - Metalmasters pads are all I've used on my '85 325e (bought new). They are noiseless, dustless (well, almost), warm quickly, and stop like the proverbial anchor!

Just my humble opinion, but I HTH.

Mark Fiumara
Arlington, VA
BMWCCA #37523
1985 325e, 141k miles and still pulls 88mph in 3rd gear!!!!