Caliper pistons seized.

[hondaman]

This is a restoration I'm attempting. Its a cb750f2 1984 with hondaline fairing attached. I cant get the pistons out. Air pressure would not pop the pistons. They have picked up the o-rings and rolled them forward. I can see parts of the rubbers poking out. Is there another way? Bath solution? The reservoir tank piston needs to come out also. Its seized in there too, and Im fighting with the last screw on the cap. Ill keep giving it a squirt with crc. Any comments appreciated.Ive already posted the front caliper photo in another forum, so I cant display it here. However, Its in the newbies and wannabies section under "what have I got? I just realized that this is the forum I should post in regards to this problem. :scooter:

[HDTboy]

http://www.kiwibiker.co.nz/forums/showthread.php?t=52115

[JeremyW]

Are you replacing the pistons? You could drill (careful not to drill the caliper) and thread. Then wind a bolt in a prize it out in a vice (after soaking I would say).

[imdying]

You've really messed it up by putting CRC on it... the seal has now swollen, possibly sufficiently to jam it up good and proper. NEVER USE CRC (or anything petroleum based) ON BRAKES. EVAR!!!11!!

Here's your options
- Grease gun and pump it out (you've stuffed the seals with contamination now, not much too lose, but a shitty idea imho)
- Use the mcyl from the bike to pump it out (might be difficult in your situation, I assume the mcyl is probably stuffed too?)
- Take it to a brake specialist that repairs cylinders. They'll have something like an air over hydraulic pump which can pressurize it with brake fluid to about 4000psi... more than enough to get it out

[imdying]

FYI: The bore in the mcyl will be toast, as will the piston be. Send the whole lot in its current state to Apex Engineering in Hamilton. Send your kits with them... they'll stainless sleeve the mcyl bore and the piston, and reassemble it for you, good as new. You are almost certainly wasting your time and money working with the bore and piston the way it is. Let us know how you get on :yes:

[hondaman]

FYI: The bore in the mcyl will be toast, as will the piston be. Send the whole lot in its current state to Apex Engineering in Hamilton. Send your kits with them... they'll stainless sleeve the mcyl bore and the piston, and reassemble it for you, good as new. You are almost certainly wasting your time and money working with the bore and piston the way it is. Let us know how you get on :yes:
thanks for the advice. Looks like it might be the only way to fix the problem. Do you have any idea what it would likely cost me. Sounds expensive.

[imdying]

Not too bad. You should be able to get the entire mcyl sleeved and resealed for about $90-100, the caliper piston, about $1.50 a mm (so about $45 ish). The caliper seals are cheap, so the whole caliper done would be in the $80 range.