Brake caliper overhaul - R65 1981

[Barry]

I didn't have compressed air either. Grease gun sounds a good idea though.

If they are tight I doubt you will do it with pliers without damaging the pistons.

[Rob Valdez 79 R65]

If you don't have an air compressor (buy a cheap one, you will need it), take the calipers to a car repair shop.  They will blow them out quickly, and probably not charge you very much.

[Bob_Roller]

The ATE caliper  pistons are no longer available from BMW, they are specific to the R65, the larger bikes had larger diameter pistons .

So treat the pistons with care .

[Ed Miller]

The ATE caliper  pistons are no longer available from BMW, they are specific to the R65, the larger bikes had larger diameter pistons .

So treat the pistons with care .

Motobins has them in stainless steel, as does that guy who I posted about some time back, but I don't know if his measurements are correct.

Or Justin could probably whip out a few dozen quickly....

[Bob_Roller]

I checked Motobins, they removed them from their online catalog about 6-8 moths ago, just checked again today and I couldn't find them .

[Ed Miller]

Oh.  Sorry.  I wish places would tell me these things so that I could keep my memory updated.

[Justin B.]

Justin could probably whip out a few dozen quickly

Yeah, right...  

[NorR65]

I have got one caliper off the bike, splitted it and pushed out the piston with a grease gun. It was a lot of hard work. Both pistons have some pitting at the top and bottom, not in the middle of the piston. The caliper did not leak before I took it apart so I think it will perform OK with new seals. Do you agree?

[Mike V]

Nor65

My guess is you'll be fine.  The piston is in contact with the square o-ring mainly in the center portion of the piston and a very small travel area at that.  Try cleaning the pistons of grit and gunk and corrosive buildup with a green scotch brite pad or 00 steel wool soaked in brake fluid.  Flush well with brakekleen and re-polish. Kind of a wet lubricated non-abrasive polishing affect.  Don't scratch or burr the piston surface where it contacts the square o-ring.  The corrosion you're seeing is probably the outboard portion of the piston exposed to the elements.  Be sure to clean the inside bore of the calipers very well and with a sharp plastic or wood (non-abrasive) tool clean the inside corners where the square o-ring rests in place.  The better for reinstallation of the piston and seating of the square o-ring.  Be sure to replace the old square o-rings with new ones.

Clean, clean, clean...

http://s428.photobucket.com/albums/qq8/gruntyman66/81%20R650%20Restoration/Front%20Brakes%205-09/?action=view&current=81R65Restoration001.jpg#!oZZ30QQcurrentZZhttp%3A%2F%2Fs428.photobucket.com%2Falbums%2Fqq8%2Fgruntyman66%2F81%2520R650%2520Restoration%2FFront%2520Brakes%25205-09%2F%3Faction%3Dview%26current%3D81R65Restoration002.jpg%26

http://s428.photobucket.com/albums/qq8/gruntyman66/81%20R650%20Restoration/Front%20Brakes%205-09/?action=view&current=81R65Restoration05-19-09008.jpg

http://s428.photobucket.com/albums/qq8/gruntyman66/81%20R650%20Restoration/Front%20Brakes%205-09/?action=view&current=81R65Restoration001.jpg

[NorR65]

I got new seals for the caliper and seals for the master cylinder from Motobins. Cleaned everything and installed the seals.
My brakes is much better than before. The caliper pistons was more pitted than I liked. I guess I need new pistons which I can not buy anymore.
Maybe other mc or cars use 36mm pistons? Any ideas?
Or can I use calipers from other BMW`s?

[Bob_Roller]

Brembo calipers from the LS will work on bikes that originally had ATE calipers, the pistons for the Brembo's are still available .

The aluminum pistons don't seem to exhibit the corrosion problems of the chrome plated steel pistons the ATE's have .

[Barry]

I guess I need new pistons which I can not buy anymore.
Maybe other mc or cars use 36mm pistons? Any ideas?

Brake pistons are relatively simple cylindrical lumps of metal with the correct dimensions. Any decent machine shop could make new ones in stainless steel using yours as a pattern.