How to remove seized pistons from brake calipers

[VentedGibbon]

Pistons seized in your calipers? Never fear!

1. Remove the caliper from the bike and remove the bleeder screw.

2. Go to your local hardware store, find a grease fitting to go into your bleeder screw hole. M8 threads. Also, get a bolt to plug the hole where the banjo bolt for the brake line goes.

3. Using your grease gun, pump grease into the newly installed grease fitting until the grease comes out of the hole for the brake line.

4. Thread in the bolt to plug the brake line hole.

5. Using any thin, sturdy, and flat object (I used my wrench), pump the grease into the caliper until both pistons are pressed against the object. You don't want one caliper to pop out while the other is still seated.

6. Pull out your block and pump the grease until the pistons pop out. It may be useful to wedge one of the pistons against the caliper itself until both have popped out. Now the fun part, get all the grease out!

I hope this helps. I saw this on a YouTube video so I can't take too much credit. If anyone figures out a good method of removing all the grease, let me know.

[littlebeaver]

Welcome to the site.....already helping out.. Cool man thanks....

[Mr. C]

Dude, next time just remove the caliper from the bracket an pump the brake, it'll push the piston ....piston's out.

[RBGERSON]

+1 do it on the bike..with the caliper hangin off.

[VentedGibbon]

I don't have the bike at my house I'm fixing it in pieces, just another way to do things.

[Mr. C]

Another way to do it if you have a compresser is use air.

[WingAdmin]

This is a good way to do it if you can't use the brake lever to pump it out, or if they are in there too tight to use an air compressor - a grease gun can develop much more pressure than an air compressor.

Brake cleaner will dissolve and remove the grease fairly well.

[djoyner]

I used this method on my '78 and it worked great!

[JWILLWON3]

HEAT WILL MAKE THE GREASE FLUID AND RUN OUT, TRY AN OLD PAN FILLED WITH BOILING WATER OR HEAT GUN !

[JWILLWON3]

ALSO INSTEAD OF FILL THE CALIPER FIRST WITH GREASE, JUST FILL WITH ANOTHER FLUID, BRAKE FLUID OT EVEN WATER, YOU STILL GET THE HYDRAULIC PRESSURE AND LESS GREASE !

[harvey01]

I wonder for cleaning if after you have done the best you can with brake cleaner and dirtied up a bunch of rags if you just put it in the dish washer, set it on hot water and let it do its thing? Of course the significant other might have some thoughts.

[Paul Narramore]

Compressed air will shift stuck pistons with an almighty bang, so I always use the bike's brakes to shift the pistons a bit at a time and by placing a thin strip of wood between the opposing pistons. A G-clamp (US=C-clamp) over the non-stuck piston too. Excellent video on YouTube too, although he separates the calipers first and uses a slave master cylinder mounted in the vice. He makes a Scotchbrite tool to clean up the bores too.

[WingAdmin]

By far the easiest way is to take one of the old brake pads, put it in the caliper, then start pumping the brakes. The brake fluid itself will push both pistons out - but usually one comes out almost all the way before the other one even starts. Having the brake pad in there means the one piston hits the brake pad and stops before it pops all the way out, and then pressure then pushes out the remaining piston. Once it too contacts the pad, remove the pad, give it a couple more pumps, and one of the pistons will pop out. The other can usually then just be wiggled free.

[tomk1960]

I've disassembled and restored at least 150 calipers with the count increasing. Many of the calipers that come my way haven't worked in years and have badly stuck pistons. I have two methods to get them out. The first is to spray a little penetrating oil around the pistons, give them a gentle, yet firm tap with a flat rod in the center to break the bond between piston and seal. Then I try to get them out with compressed air making sure to have an old pad in place to keep them from flying out. If that doesn't work, my YouTube method always works. The grease method is clever, but very messy to clean up afterwards. Brake fluid is easy to deal with.

Whatever works for you is good with me!