Front Brakes Prob 91 kdx

[bigo]

Hey all i decided to replace my front pads and stuffed around and pumped the caliper piston out.
nehoo after sitting it back in and bleading the brakes i cant get the piston to move back out.
ive got a clear piece of hose and the fluid is coming though with no bubbles.
also there was an oring bit smaller then the piston that came flying out aswell did this just sit in the bottom of the caliper?
ne ideas what im doing wrong?
cheers

 

[CTurbo]

That O ring is the seal that goes between the piston and its bore. Thats why the piston don't move.

 

[blackduc98]

CTurbo is right. It is time for you to rebuild your caliper. If you don't have a factory manual then take a look at the parts diagram available on-line, and hopefully it will make things clear:

http://www.ronayers.com/fiche/400_0...kdx200_e4.cfm?man=ka&groupid=4830&parent=4730

BTW, without the o-ring I would expect to see brake fluid leaking from the caliper when you squeeze the lever (assuming there is no air in the brake line). Do you not see the leakage?

 

[bigo]

its not leaking,
there was also a seal and dust seal in the caliper + this oring? maybe the oring was from something else and i just looked like it blew out of it.

 

[blackduc98]

Hmm.. there are very few parts in the caliper. You should be able to match them up against the parts diagram, and you should hopefully be able to figure out where this mysterious "extra" o-ring came from.

BTW, when you squeeze the brake lever, what does it feel like? Spongy? Or does it feel like it hits a hard stop?

When I rebuild a caliper, during final reassembly I lubricate the bore, the piston, and the o-ring seal with brake fluid. Then I push the piston into the bore. Then I apply a tiny bit of air pressure from my compressor into the banjo bolt hole to make sure the piston moves smoothly, which of course assumes that the caliper was disconnected from the brake line, and is sitting on my workbench where it is much more convenient to work on it. With the piston about half-way in I fill the caliper with brake fluid thru the banjo bolt hole. Then I gently push the piston in till brake fluid starts to come out of the banjo hole - basically I'm trying to get the air out of the caliper in preparation for the final bleeding step.