rebuilding brake calipers

[Hilter9053]

Since I first bought my car the brakes have never worked well. The brakes have been really squishy. I bled the lines all day and got nowhere. I was thinking that I should rebuild my calipers and I do not know how to do this or what is involved. I just need to know some general info or any other suggestions on what is wrong would be greatly appreciated.

 

[frankenstein406]

i have to do this to i have 3 pairs of bad ones, i think you pop out the piston, theres a snapring indside and its easy from there.

 

[Calan]

i think you pop out the piston, theres a snapring indside and its easy from there.

If the snap ring comes out with the boot, it's easy...if not, it can be a bit of a pain to get the ring out. A dental pick works nicely. Just be careful not to scar the cylinder wall.

Stuff a rag under the piston to catch it, and run a few psi of compressed air into the brake line port (it shouldn't take much). The piston should pop out, but be careful...it can come out really quick and forcefully, so be ready for it and watch your fingers. Use a flat blade screwdriver to carefully pry out the boot and snap ring, and then use a dental pick to remove the seal that sits below the boot. Clean everything up real nice, lube the cylinder with some brake fluid after installing a new seal, and then put the new boot and piston in.

If you have a little corrosion on the piston or cylinder, you can use some 1500 or 2000 sand paper (lightly) to remove it. For the piston, I wrapped a rubber sanding drum in a few turns of ductape and then slipped the piston over it and tightened it down...and then spun it in my drill press while very lightly buffing it.

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The cylinder is a bit hard to reach into, but I just buff it lightly by hand and then clean it really good. If your piston or cylinder is pitted you'll probably need to just replace the caliper.

Here are a couple of threads with some helpful info:

http://www.dsmtuners.com/forums/handling-tech/263002-resolved-rebuilding-calipers-need-help.html
http://www.dsmtuners.com/forums/handling-tech/187984-rebuilding-calipers.html

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For my early '92, the part# for the Mitsu front rebuild kit is MB699707. It contains the boot and snap ring, piston seal, and new boots for the caliper mounting pins. It runs about $39 a side (retail at Mitsu dealer). NAPA also has a kit which contains everything but the pin boots, for $8 per side. You can get all 4 pin boots (driver and passenger sides) in a separate kit from them for around $15.

I'm in the middle of doing this during my rebuild...I'll try to write a tech article on it if I get time in the next couple days.