rebuilding Mark VII calipers

Topic: rebuilding Mark VII calipers (Read 1152 times) previous topic - next topic

rebuilding Mark VII calipers

June 17, 2013, 07:45:03 PM

I've never rebuilt a caliper. I want to do these myself because A; I want to learn how to, and B; I'm a cheap, broke SOB that just lost my job and I don't have a lot of disposable dollars for new calipers. BTW, these are the fronts, and I also have the rotors. These will be going onto my '84 Mustang (with the proper 11" spindles

) for the 5 lug.

Is there any special tools I'll need, or anything specific?

I could google, yes, but I know you guys have better, more concise answers than some drunken twit who lacks proper English understanding.

TIA.

rebuilding Mark VII calipers

Reply #1 – June 17, 2013, 08:07:38 PM

First question, before you go too far. Do they have the stainless steel, or phenolic pistons? I've had too many phenolic ones bind up on me as they've aged. They'll bind up and get stuck AFTER you've pressed the pedal, and won't return, thus locking up the caliper on the rotor. I would suggest getting new stainless pistons, but you might get lucky reusing the phenolic.

There's really not much to it. I usually use a little air to pop the pistons out of their bores (Keep your fingers clear!). It doesn't take much to get them out, so don't go nuts. I've even used a bicycle pump before. I also put a small piece of wood to give the piston something to hit besides the caliper. Especially key if you have phenolic pistons you're planning on reusing.

After they're apart, it's pretty much a clean-fest. I carefully clean any corrosion/residue off with a ScotchBrite pad or the like. Trying to avoid making any heavy scoring of the piston or caliper. Make sure you clean the o-ring seal groove in the caliper. Blast things out with brake cleaner and then reassemble with a light coating of brake fluid on the internals. There are like 4 parts, so it's kind of hard to screw up.

One upgrade you should do, if you can swing it, is ditch the rubber caliper pin/bolt guides. There are aftermarket metal versions out there. The rubber ones allow the caliper to move around a bit too much. Speaking of caliper pins/bolts. Clean them well, or replace them if they're too far corroded. Ideally you should replace them, but I've found some of the aftermarket replacements to be , so I've either cleaned what I had, or bought new OEM ones.

rebuilding Mark VII calipers

Reply #2 – June 17, 2013, 09:14:44 PM

I'm not sure what the pistons are..I'll be head out to the shop later, will definitely check. Looks like I may be set, have plenty of brake cleaner and a good bit of scotchbrite pads.

Thanks for the words Chuck :)

rebuilding Mark VII calipers

Reply #3 – June 18, 2013, 08:40:05 PM

First thing to do is make sure the bleeder can be removed and the threads are good. No need to rebuild a caliper to find out the bleeder is busted off or seized in the caliper!!!

For what it is worth i rebuild all my calipers. BUT make sure you can buy the kits. Many are obsolete and many more just dont have kits listed. Phenolic pistons are ok but i dont like them.The new TEFLON coated ones are the best if available. The newer Phenolic pistons are made differently have more clearance and are not pr0ne to exorb moisture like the old ones. But basically i do not use them once again. The trick is simple installing the outer boot. There is a tool for that but it is not necessary in most cases. All you have to do is put the outer boot over the piston all the way to the end and i never use brake fluid to assemble calipers. There is commercial assembly lube but i like Dielectric grease for 2 reasons. One it makes the components easy to assemble. And 2 i pack the outer groove with it. This way the outer lip of the seal in the groove does not corrode and eventually seize the caliper. Especially on cast iron calipers. If you use brake fluid it corrodes very easily. The Dielectric compound should be packed in the outer groove to keep moisture out of the groove and seal. Normally that is where they get hung up.

When installing the outer boot as i pointed out above install it all the way on the piston and screw the lip in to the groove then when it is in all the way push the piston in the bore. Just me this is how i do it there are many other ways just my preference. You can also buy the spreaders to install the piston after installing the outer seal assembly. The tool spreads the seal open and all you do is push in the piston. Then the tool pops out. Simple takes 5 minutes to do it.

Finished!!!! Notice the special cap i use on the bleeder it keeps out moisture from the bleed hole and also the threads. I also bead blast all my calipers before dissembling them. I never bead blast the bore or the lands, NEVER blast the piston also.

rebuilding Mark VII calipers

Reply #4 – June 19, 2013, 04:18:31 AM

Good writeup Tom, Thank you!