Where to buy brake caliper pistons

[drswift]

This goes in the "bonehead" file for sure, but I tried to make my own tool for removing the rear brake caliper piston on my R11RT. It got stuck in that little center hole, and in removing it I broke out some of the piston center, enlarging it to the size of a pencil width. The dealer says I have to buy a whole new caliper ($300+!!). My two questions: 1. Is there a source for just the pistons?, and 2. What's the risk of riding with a damaged piston on the rear brake?

 

[kpjensen]

look for a used one @ beemerboneyard.com

 

[drswift]

Yeah. Found a used caliper there. I'm still curious about just finding pistons. Also, that little brass hex clip holding the brake pad pin can only be bought as part of a $19 brake pin assembly from BMW! Another parts scam.

 

[PGlaves]

The easy way to remove brake pistons is to push them out with a few puffs of air from a compressor and a rubber tipped blow gun. A couple of puffs is all it takes. Careful not to slam it out and pinch your finger. Experience hurts.

 

[dlearl476]

Not familiar with that particular model, but chances are they are brembo brakes. Try www.cyclebrakes.com. If anyone has a repair kit, or a piston, it will be them. If not, the caliper with be cheaper than at a BMW dealer.
If Melissa is there, ask to speak to her. She's the Queen of Calipers.

 

[drswift]

Thanks, Dave, for the Cyclebakes lead. I'll give them a call this week.

Still no comments about riding with a damaged piston. Logic tells me that the strength of the piston comes from its circumference, not its surface. Any thoughts?

 

[dlearl476]

Thanks, Dave, for the Cyclebakes lead. I'll give them a call this week.

Still no comments about riding with a damaged piston. Logic tells me that the strength of the piston comes from its circumference, not its surface. Any thoughts?

I'm a little confused. In your OP, you said you "broke out a little of the center" of the piston. I would understand that to mean the top. Also unclear about what you mean by the "strength" of a piston. It's "strength" i.e. the qualities that make it work, or not, are it's ability to perfectly seal one side of it from the other side of it in the cylinder, so that brake fluid doesn't leak past it. It's "strength" i.e. how hard it is, is relatively unimportant.

 

[fourbmw]

Go to the website "tawvehicle.com". If I am correct that the calipers are still made by Brembo, you can follow the directions to the repair parts listings. Years ago I completely rebuilt the calipers on my k75.

 

[drswift]

you said you "broke out a little of the center" of the piston. I would understand that to mean the top. .

Yeah, the top of the piston with the little hole now has a big hole. This rear caliper only has pistons on one side (only one side of the pads is being compressed. ) I don't see any fluid leaking out, and the brakes seem to work fine (given what little I use the rear brake.)

 

[Kev95gs]

I just rebuilt both my front and rear calipers.

The original pucks for the front were hollow in the center. The new ones have an "insert" that is higher than the height of the puck, but the same height as the original, the insert is the portion that actually makes contact with the pads and pushes them to the rotor.

I was told that there was no replacement pucks for the rear and that you would have to replace the whole rear caliper, if you had broken a puck/piston, as well. I removed the rear pucks using compressed air, replaced the seals, cleaned and reinstalled the original pucks.

My concern would be that the "insert" would somehow break in two, leaving one puck longer than the other causing uneven pressure from both pistons or that the broken one could be forced out due to the uneven heights, causing a complete loss of brake fluid all over your rear wheel and no rear brakes. (I hope this makes sense).

If it were me I would find new pucks or a new/used caliper and replace.



Kevin

 

[drswift]

Thanks Kevin. I exhausted all sources and the consensus is that with an older bike my options are a used caliper (which I ended up getting from BeemerBoneyard) or a new one. It was the top of the "puck" that had the damage. A number of mecanics have told me it's no big deal, that Brembo put these covers on motorcylce calipers to limit road dirt. On all the high-end car brakes they make and even other new sport bikes the pistons are just open ended tubes.
At least now I have another spare piston and a few replacement parts.