Front Caliper rebuild problem

[CUBuffs]

Can someone tell me please what is the secret to reinserting a piston into the caliper. I have my front calipers off and the rebuild kit from Partsnmore but I can't seem to get the piston past the new O-ring. I'm using a little brake fluid as lubricant and I've been told that it shouldn't take more than thumb pressure but that does not seem to be working. Thanks.

[randy]

Cubuffs,

Have you thoroughly cleaned out the recess in the caliper? May be some debris taking up some space, tightening the o-ring?

Also, helps to put the piston in the freezer for an hour. Shrinks it a bit. Put it in a plastic bag, don't want any frost on it!

[CUBuffs]

Except for very small amounts of something that I can't seem to get out it looks pretty clean. I have only used brake fluid for cleaning, what else would you recommend?

[GNEPIG]

.. you do have the bleader screw removed from the caliper right?
if not try it that way
.what happens to cause the pistons to stick in the caliper is that oxidation accumulates under the Oring causing the inside diameter of the Oring to be smaller than the piston, then the piston wont move back into the caliper and release the brakes.
. bend the end of a wire coat hanger and scrape the inside of the groove. this should give you white powery stuff (oxidation) keep scraping until its all out
.. if this is not the case than the parts you have bought from partsnmore is wrong
good luck and keep us posted

[CUBuffs]

Gentlemen, thanks for the info. After applying your tips I was able to reinsert both pistons.

[Winterhawk]

I've ran into several kits that the square o-ring is to large. Hard to tell with the naked eye as the difference is so small yet large enough to make them stick.

[CUBuffs]

Ok, I finally have the piston in and the caliper mounted but it seems to have a little bit of side-to-side play in it. It doesn't feel real solid. Could that be because I have not filled the lines and bled them yet thereby making the piston hold against the rotor?

[randy]

CUBuffs,

That could very well be the play between the pads and the rotor. Very important to coat the backs of the pads to cut down on squeal.

Some guys use the gooey glue stuff, some use white grease, depends on your preference.

[CUBuffs]

I read somewhere that I should place a little brake fluid on the backs of the pads and on the rim of the pistons, which is what I did. Do you think that will work?

[randy]

Sorry, never heard that one before.