Originally Posted by kedwards005
How did your caliper rebuild work out, good...bad...? I found I have pistons which are sticking on the right front caliper while replacing brake pads. Anything you can share would be greatly appreciated!
1972 R60/5 Toaster
I'd say the rebuild was a success.
One thing to note, first. The rear caliper halves have a crossover tube to let brake fluid travel from one side to the other. The tube has standard brake line fittings. The front calipers do not appear to use a tube. Instead, like airhead BMW M/C calipers I've rebuilt, the front halves appear to have an internal fluid passage that uses an O-ring at the joint between the caliper halves to prevent fluid from seeping out. That's just from an outside look at the front calipers on my bike (a 2002 like yours), though.
The rebuild was actually very simple, and like any other caliper rebuild I've done (except with the crossover tube). I took the halves apart and cleaned them up with spray brake cleaner. Sprayed brake cleaner through all the passages to make sure they were clear. Bought the rebuild kit from a BMW dealer. Kind of pricey, but what else was I going to do? The kit came with new seals, new pistons, and some lube to use on the seals and pistons when putting them in the caliper halves. I also replaced the rear brake hose while I was at it. BTW, the banjo bolt that connected the upper end of the brake hose to the brake line was absolutely stuck and I destroyed it getting it loose, so buy an extra banjo bolt or two, and some extra crush washers, too. I recall the diameter of the bolts holding the halves together was M8. I used some blue loctite and torqued them to about 15 Newton-meters (NOT FT-LBS!!!!), I think. You can get some torque info here - http://yetmans.mb.ca/kohler/page3/page3.html
Put the brake hose and the caliper on, filled the wheel circuit, and bled the rear control and wheel circuits (took some time, but not a difficult bleed job).
Went for a test ride and came home. No leaks, but the brake pads were still rubbing the rotor more than I felt they should. Took some more test rides of increasing distance and decided to see how hot the rotor was getting. Couldn't hold my fingers on it, so it was VERY HOT. I'm embarrassed to say that at first it didn't dawn on me that what made the rotor VERY HOT was that I used the brakes to slow the bike right before checking the rotor temp. Duh!!! So, after I got my head out of the clouds, I took another couple of rides up the interstate and let the bike coast to a stop at a rest area. Success - the rotor was warm at best and I could keep my fingers on it easily. The rotor was not discolored and did not have any other indication that it overheated. So, I would say my rebuild was success.
Good luck with yours.