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Fractured Face / Edge on Rear Caliper Pistons - Replace?


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Bike: 2003 R1150RT


Due to a lost caliper bolt that went unnoticed for some time, I suffered some damage to my rear braking system (caliper was held only by front bolt and tilted up/forward as a result).


For safety sake I replaced the disc and pads of course, however, I also noticed crumbling of the face of the rear caliper piston (attached image).


I am leaning toward rebuilding the caliper but wanted a second opinion (maybe I am too paranoid).


Assuming a rebuild is in order (it looks horrific to me), I can't seem to find the rebuild kit for the rear caliper that includes the piston. BMW only lists the seals? Anyone have a source for a complete kit (seals and pistons)?




Edited by Claudio
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You might take a look for a good used caliper. Put the caliper part number into a search - 34217660271 - and you should find a caliper available. Looks like approximately $46.


That piston on yours is probably okay but you have to make that call.

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Same bike , same problem. My caliper fell off at 70 mph and I didn't notice till I got off the bike about an hour later. I think all the braking I did caused the cracking as the Pistons were not pushing on an even surface. That was 70,000 miles ago. Still using the same caliper. I do check for degradation when I change pads and haven't noticed any, so I pretty much gave up worrying about it.

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Good to here its a plastic cap of sorts on the piston and nothing more. I'll monitor it for now and live with it.


Brake and new disc are in and working just fine.

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Thanks Lowndes. These are great sources I didn't know about.


Unfortunately the rear calliper (26/28 mm) has no rebuild kit that includes the pistons/pucks.


I ended up ordering a used calliper (complete with ABS sensor and brake line which I don't need but a spare set of parts for my aging bike is never a bad idea).

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