My rear caliper on my 1995 R11000 with 80K seized. I purchased a new set of seals and stripped the caliper. To my surprise there is absolutely no marks on the brake pistons, they are completely clean. I have changed the brake fluid annually. The new brake seals were fitted and the brakes bled successfully The problem is that for some reason the caliper still seizes but not on a regular bases. It will behave itself for a couple of weeks and then seize. Within 10 minutes it will unseize and will not do so again for a few days.The bike has ABS 1. Is there any possibility that that the ABS module is not allowing the pressure to fall and, for some reason, maintaining the rear brake on? Is this a stupid idea? any one any other ideas?
Rear brake caliper seize
- Thread starter Peter
- Start date
stuart kerr
Registered user
Bendy toy
Registered user
Have you used silicone lubricant on the brake pistons? It causes them to slip too easily through the seals so there is nothing to pull them back when the brakes are let go. Try cleaning the seals and pistons with alcohol and refit with only brake fluid.
If that don't work it will have to be a new calliper.
Maybe
A knackered rear brake hose
They break down inside and or balloon
Can cause these symptoms collapsed rubber inside forms its own non return valve
Happened to my 99 1100 at the front, pipe knackered above splitter on fork causing front brakes to bind on
Stainless lines fitted jobs a good un
Frank
A knackered rear brake hose
They break down inside and or balloon
Can cause these symptoms collapsed rubber inside forms its own non return valve
Happened to my 99 1100 at the front, pipe knackered above splitter on fork causing front brakes to bind on
Stainless lines fitted jobs a good un
Frank
what he said !!!!Flying banana
Registered user
Ah, there you go, there's yer problem. THose R11000 models were too powerful for the braking systems, so they kept seizing. Apparently, BMW reduced the engine size to 1100 in the end becuase it was such a problem.
I'll get my coat.
ChrisH Kerry
Registered user
What about the pin that goes through pads? If it's worn with a ridge that can stop pads freeing off properly. You probably checked that already....
Mates r850r did that, I swapped caliper for my good used spare, no joy. Changed the old rubber line, again no joy. it was actually the rear master cylinder.
Once it was replaced no further problem, on stripping the old cylinder it had a ridge near the bottom of the bore and was causing the brake to stick on .
Once it was replaced no further problem, on stripping the old cylinder it had a ridge near the bottom of the bore and was causing the brake to stick on .
What is seizing ? have you seperated the two halves of the caliper and cleaned up and greased the two sliding caliper shafts ?
Sliding pins can be an issue as Steppers says
But also as mentioned above the rear hose. If it's sticking on? I had a couple with a rear hose that had de-laminated inside and when you applied the brake it pushed the pistons out okay but the "flap" of inner prevented them from releasing fully
I guess it was either the repeated application of the brake that pushed the pistons closer and closer OR friction from them being continuously partially applied made heat and expanded the fluid etc etc until the brake was on pretty much fully on
releasing the bleed nipple let the pressure off and they could ride for another while
Simple cure replace rear hose
You can also test by simply trying to push the pistons back with your thumbs if they won;t go release the bleed nipple and try again if the do the problem is upstream
Ride Safe you don;t need a sticky brake with all the leaves about!
But also as mentioned above the rear hose. If it's sticking on? I had a couple with a rear hose that had de-laminated inside and when you applied the brake it pushed the pistons out okay but the "flap" of inner prevented them from releasing fully
I guess it was either the repeated application of the brake that pushed the pistons closer and closer OR friction from them being continuously partially applied made heat and expanded the fluid etc etc until the brake was on pretty much fully on
releasing the bleed nipple let the pressure off and they could ride for another while
Simple cure replace rear hose
You can also test by simply trying to push the pistons back with your thumbs if they won;t go release the bleed nipple and try again if the do the problem is upstream
Ride Safe you don;t need a sticky brake with all the leaves about!
Thank you all for your helpful replies, much appreciated. I have split the caliper, fitted new seals and re-assembled using brake fluid only (no silicone grease). I fitted braided brake hoses, rear and front a few years ago. I like the idea of investigating the slave cylinder and the pin that holds the pads, as it is very old. I think the idea of slackening the bleed nipple to release pressure is good.
Steptoe, I presume one or more of the pistons is reluctant to retreat back into the caliper. What are “ the two sliding caliper shafts” you mention?
Steptoe, I presume one or more of the pistons is reluctant to retreat back into the caliper. What are “ the two sliding caliper shafts” you mention?
The rear caliper is a sliding unit. There are two big pins with rubber dust boots that it slides on. If these are gunged up and not sliding properly then the caliper will bind and not release properly. I strip and clean mine every winter (during the brake fluid change). There's a long winded but comprehensive write up on rear caliper maintenance on ADV.
I clean and grease them on customers bikes every time i change the rear pads.
On my own bikes once a month i push the caliper body with my foot forcing the pistons in and causing the sliding pins to move along their full length so they shouldn't have time to seize due to minimal movement. A 5 second job
Also i find 1200 models seem to seize more than the 1100/1150 models.
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