Rear Brake Piston Frozen Need ideas

[davestrike]

Hello All,

Well I have been working away on refurbishing my old beauty and ran into a bit of an issue.

The rear brake piston is frozen inside the chamber.

Yes I see some rust on the outside facing towards the disc.

I tried filling new oil in the reserve and in the brake on the rear, bleeding it, to use that as a way to pop out the piston. No dice.

Any ideas on how to break it free without maring up the piston? Or completely toasting the rubber seals?

Thanks for any help!

[TopCatGr58]

Hey Dave,

Don't worry about marring up the OUTER edge of the piston that makes contact with the pads, just don't grab too far below the seal edge once it starts coming out. I had both of mine that were totally stuck. I used PB Blaster, and then a blow dryer, but a heat gun would be just as good to heat up the housing. I put the caliper in a vice, and used a pair of slip jaw pliers to grab the piston and rotate it, kept squirting the penetrating fluid, heat, rotate, and once it broke loose and could spin, then I applied vertical pressure as I rotated it, and was able to twist it up out of the caliper bore. My seal was not damaged from the penetrating fluid, I cleaned it all up and put it back together, been 6 years now, and still work just fine!
T.C.

[dpotter58]

I popped mine out with air pressure but they weren't tightly stuck.
I used a blow gun in the brake line hole

[davestrike]

Top,
I will give your idea a go. dpotter, I do not have air pressure available, well they do say I am full of hot air, but I know I do not have that much in me!

[fredintoon]

Grease gun!

Hi Dave,
find a grease nipple the same thread size as your caliper bleed nipple and fit it into the bleed nipple hole. Connect your grease gun to it and pump. A good lever-action grease gun will develop perhaps 10,000 psi. If that don't shift it, look for another caliper. Safer than air, too. A piston freed with air pressure comes flying out like a bullet. A grease-driven one just goes splurt.
Fred Hill, S'toon.

[John]

Grease gun powered pidton removal method

I have been a staunch proponent of using a grease gun to remove frozen caliper pistons for a ong time. It works when all other methods fail. You won't need to find a grease fitting, just use the bleeder screw. The grease gun coupler will latch onto it just fine. You will want to find a bolt to use in place of the banjo bolt that attaches the brake hose, or you can wad up some paper towel and stuff it up into the banjor bolt to prevent the grease from oozing out of it. As soon as the piston is out, remove the square O ring in the caliper and clean the grease from it, scoop the grease out of the caliper, and then use some brake cleaner to clean the remaining grease out of the caliper.

[davestrike]

I got the caliper out!

I used a rubber piece with pliers after soaking in some brake cleaner.

A few turns and it slowly came out.

Found out what was holding it in, oxidization. All kinds of white gritty stuff that I am still cleaning out.

The rubber seal is intack and in good shape.

Thanks for the suggestions all!