Caliper Rebuild

Q: Caliper Rebuild

How do I rebuild my calipers.

A: I’ve had my calipers apart a few times. Rebuilding them is nothing more that replacing the seals unless the piston bores are corroded or damaged. Then you’ll have to have them re-sleeved (about – $35 per piston – expensive). I took them apart several years ago but didn’t replace the seals. Ever since I’ve had a problem with air getting into the system and having to bleed the disks about once a week. I never found a leak so this rebuild kit is an attempt to rule out the calipers. I’ve already replaced the wheel hoses and rebuilt the master cylinder, so I’m down to the calipers. I do have one question about bleeding the calipers to remove air behind the pistons. I don’t think the standard method of bleeding them like drum brakes accomplishes this. Does anyone know of another procedure?

A: I’ve always used one of these standard methods to bleed the calipers:

Two Persons – One pumps until peddle firm the hold, Other person loosens bleeder until pedal hits floor then re-tighten, Repeat until fluid is clear;

One Person – Use a 1/4 vacuum line attached to a piece of clear tubing, slip vacuum hose over bleeder and clear tube into bottle filled approximately 1/4 full of brake fluid, check to make sure the end of the tube is submerged in fluid, Open bleeder and pump peddle 4-5 times, Refill master cylinder and repeat until fluid in clear tube is clear.

Be sure the bleeder is at the highest point. After pumping a few times, try tapping the calipers lightly with a hammer. If there are any bubbles in the fluid, this will help float them toward the bleeder.

Another thing to check is the proportioning valve. On my 1969 convertible, the proportioning valve was sucking air in but not leaking fluid out. I bled the calipers many times before tracking down the real problem.

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