TR6 Brake Piston Tight

[Matt1969]

Hi, I am just changing the brake pads. Got three in without too much trouble, levering the brake pistons back. Last one though is solid. Any thoughts? Is this normal? 

[harrytr5]

No it is not! Maybe rust on the piston? Guess you will have to remove it  and work on it, on your bench.Compressed air  should get it out to inspect. It will pop with a bang so have a cloth in the area to soften the blow. Good luck!

Big Red has a good record on fully rebuilding them if need be.

Regards Harry

[Dave McDonald]

If you take the caliper off it can sometimes help to free it initially by pushing it back into the caliper, using say a G clamp, before then trying to blow it out with compressed air as Harry suggests. If you use compressed air you will need to hold the free piston in place with a G clamp so that it doesn't blow out first and all the pressure is concentrated on the stuck piston. Be prepared for brake fluid blowing out all over the place. It can be helpful before trying to blow the piston out if you apply the compressed air with the bleed nipple open with a cloth over it to evacuate the fluid first, before closing the nipple to blow the piston out.

Good Luck.

Dave McD

[rcreweread]

Make sure the master cylinder isn’t full to the top with the top on, hence nowhere for the fluid to go - the vent hole will allow some to escape ( and strip your paint) but possibly not enough quickly enough when trying to push piston back

cheers Rich 

Edited May 25, 2022 by rcreweread
clarification

[ianc]

Remove the pad from the piston which is stuck and replace the pad with something solid and somewhat slimmer (metal or timber, for example).

Press very hard on the brake pedal and the piston should move forward.

Remove the solid material and lever the piston back into the calliper - try to lever across the face of the piston so as not to tilt it.  This is not easy!

You may need to repeat this action a few times in order to free the piston such that it will slide fully home into the calliper.

As Rich advises, keep an eye on fluid level in the master cylinder as the piston is pushed back.

When TRs were the daily driver and we drove more furiously, pistons seldom stuck because they were moved more inside the calliper.  As we get older, the cars are used less frequently and we don't stand on the brakes from 90 mph approaching each roundabout, so the pistons can (and do) get stuck.  The best advice is to use the car as often as possible and, now and again, brake really hard from a reasonable speed (no, not 90 mph nowadays!).

Ian Cornish