Hey guys and gals of Fiero world. I have just completed rebuilding 4 '88 rear calipers with the pressing apart of the inner piston. All 4 were leaking from the piston vent. I believed the seal to be faulty but all 4 looked pristine. Very pliable and not wrinkled or torn at all. They all look new but the leaking was happening still. What I found mainly that there was a bad buildup of dried brake fluid/moisture globules that I used a small wire wheel with a Dremel to buff out the inner piston surface. Reassembled and installed on 2 cars now 3 months-no leaking any more. I used the Fierostore rebuild kits for the other parts. What do y'all think?

IMHO: The rear brake piston actuator (parking mechanism) can be one of the most neglected maintenances.

Glycol-based brake fluids (Dot 3 and 4) are hygroscopic, which means it attracts and absorbs water molecules from the surrounding atmosphere. Once the corrosion inhibitor additives in the brake fluid are spent; moisture contamination leads to corrosion or ‘rusting’ of metal components. These compromised parts can begin to slough off some of their materials.

It is critical to monitor the fluid with test strips before moisture contamination builds up in the braking system.

As a preventive maintenance, I flush/purge all brake fluid including the clutch master/slave cylinders every two to three years...

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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

Nice info Vintage Nut, I think brake fluid is the most neglected fluid as I confess i bought my Red GT brand new and have never done it! I shouldn't be surprised at the build up inside my pistons. Surprised at the quality of the original GM inner seal, I am guessing Viton or EPDM ? A custom rubber company in New Jersey said they would make them in Viton for what would end up at $70 each if i ordered 100 pcs!

my 1988 parts car/maybe future project seems to still have brakes after sitting in a field for years. i thought since theres fluid in there they would be safe but i wonder if i should remove them and store them in some kind of liquid.