I’ve had my TTR 250 1996 for 10 years . The master cylinder failed a few years ago, with rear brake sticking on, and I replaced it with an aftermarket one. The rear brake started sticking again last week and cracking off the master cylinder high pressure connection didn’t free the rear brake so that pointed towards the caliper. Sure enough, the caliper piston was quite stuck, so I stripped down the caliper and removed the piston using the brake pedal. I immediately tried to re-assemble the piston without the outer dust seal but with the old inner fluid seal, but it was almost impossible- I suspected a swollen fluid seal etc. I removed all seals and cleaned everything up and tried to assemble the piston into the caliper but it would not go in. The piston appears to have swollen, it looks like it may have some sort of thin rubber coating, I’m not sure. Perhaps this coating has swollen. Has anybody encountered this before? Any help appreciated.
