Caliper Rebuild Problems (Help Urgent)

[crackerkorean]

Ok I am in the process of rebuilding my caliper and the tear down was just fine. But the rebuild it being a pain.

I was able to get the piston to get past the first seal but not the second one.

Should I just use a C Clamp to push the piston in the rest of the way?
this is the last major thing to do before I get my tank.

[Kevin]

thats how I do it. make sure your bleed screw is open.Kevin C.

[louthepou]

Yup. Also, make sure you have a bit of brake fluid on the seals so it wil help the piston slide in. Make sure you apply pressure evenly, and that the piston stays straight.

Louis

[crackerkorean]

well I used a C clamp and the piston didnt go in straight and I have an air leak. spent an hour of just bleeding the brakes to find this out.

so how do I get the piston out so that I can try to re seat it. And please tell me that I didnt waste 50 bucks on a rebuild kit.

I guess I an a gluton for punishment, either way I need some help.

[Walt_M.]

I use compressed air to get the piston out of the caliper but be careful, it will come out really hard. Aim it at a box of rags. You may have damaged your seal when you forced it in, I have always been able to get the piston in by hand, lots of brake fluid on everything.

[crackerkorean]

Could I use the old seal? Or did I just spend another 50 bucks?

Also how did you get a good seal where the brake line goes to pop  the piston out?

[louthepou]

I've been able to reuse old seals in the past, when that's the only choice. Make sure it's clean, clean, and without any minuscule crack.

I've also revived some old calipers that were so full of grime that I had to work with a dremel spinning a brush to clean all that was stuck in there, even in the groove where the inner seal sits. That, maybe, could be enough to make the seal be just too tight.

When a piston is really jammed in, I use my compressor and put some pressure in by one of the holes. I leave some oil in, and also lube the exterior side of the piston to help it slide. It can take some time. Only once did I have to use vise grips to remove (and therfore kill) a piston.

And I understand how you feel - I had to buy a whole kit too just because I was one seal short...  >:(

Hang in there!

Louis

[Kevin]

The square piston  seal is pretty rugged. If you want you can pop the piston back out with compressed air and look it over. To do this use a air wand or pistol and wrap the end with electrical tape to form a taper. I clamp the caliper in a vise and put a wrench across the piston so when it pops out it doesn't go airborne. I'm still using the orgional piston seals.  I do like to polish the piston and housing a little with mothers metal polish before reassembly.Kevin C.

[crackerkorean]

I am going to stop by the shop today and see if they can help me out. I might have them put the pisto back in if the seal is not toast. If it is I am going to have to wait till payday to get another kit.

[louthepou]

Seems like a prudent approach. Let us know how it turns out,

Lou

[crackerkorean]

The shop was unable to get it out. They were able ot pust it out about 1/16th of an inch.

Any other ideas??

Does anybody have a working caliper for sale?

[jasonm.]

Sorry about your problem. I have done rebuilds and cleaning of bike calipers many times. BUT...If it takes more pressure than with your fingers to get the piston in...STOP. The seals are not in correctly or have been displaced.  Try a bigger compressor????

[crackerkorean]

The motorcycle shop put 120psi on the caliper and nothing. well lesson learned. I am getting a caliper from super fly. So hopefully I will be getting on the road soon.