Need Caliper Rebuild Help!

I can't get the second piston out of the caliper! How do I used Compressed air? (The first time I just used the brake fluid to force the problem one out, btw is covered with gunk, and undoubtedly the problem!)

Thanks!

elGato

 

Put the other piston back in and hold it with a c-clamp. Use compressed air or grease gun to push the other out.

 

that or what i did was use one of the caliper mounting bolts to plug the brake line hole on the caliper, it's the same threading on my bike. then shot it with the grease gun

 

You mean the OTHER piston, from the second caliper?

Take the caliper off, and use the "grease gun" trick. It's much safer than compressed air (which never works well for me.)

The "gunk" on the outside of the piston is not the cause of your problem.

It's the built up dried crud behind the seals in the caliper body that is causing the problem. The key to this whole exercise is to get those seal channels dentally clean without gouging them up. If you "kiss" the dried crud with a propane flame it's easier to get it all out of there; but you'll probably need to repaint the calipers if you use that option.

 

I found that some 0000 steel wool works well in the seal channels in the caliper. Be sure to use plenty of brake cleaner to get any remnants from the steel wool out. Like fitz says, they must be clean. Then just a light honing of the caliper, you don't want to remove too much material.

If your pistons have any surface pitting at all you will need to replace them.

 

Thanks for the help! I ended up figuring out the grease gun trick on my own! Then I used a dremel to clean behind the seals! And I replaced the pistons! Took it out today, and it fixed here problem with overheating my new rotors! It's ready for my summer trip now!