Caliper Rebuild Question

[greatnw]

Putting things back together. All the pistons in all my calipers on my 80SG were frozen. Only one piston needed to be replaced. I cleaned up all the calipers. Did not replace the rubber rings. One is so tight I can't even push the piston in. I'm guessing that is the signal that I need to get a rebuild kit since the rubber must have expanded?
Am I missing anything?
Thanks in advance.

[DiverRay]

Did you pull the rubber OFF THE PISTON??? If you did NOT, that is probably your problem. You NEED to clean BEHIND the rubber seal, so it will shrink back down. Use ONLY brake fluid to clean the rubber, but you can use brakeclean or almost anything else on the piston. Try a stirring stick with one end "cut" so it's square to clean the gunk from behind the seal.

[fredintoon]

Putting things back together. All the pistons in all my calipers on my 80SG were frozen. Only one piston needed to be replaced. I cleaned up all the calipers. Did not replace the rubber rings. One is so tight I can't even push the piston in. I'm guessing that is the signal that I need to get a rebuild kit since the rubber must have expanded?
Am I missing anything?
Thanks in advance.

Hi GNW,
it's never wrong to fit new rubber brake parts, it's cheap insurance.
Did you carefully measure both rings?
Is the one that won't fit fatter than the one that will?
Did you pay special attention to cleaning out the ring groove?
Any crud built up in the groove will lessen it's depth to give a too-tight fit.

[greatnw]

I used my flexible rotozip tool with a wire brush on it to clean the groove.
Probably got some brake cleaner on the rubber before I fished it out. Maybe even some TriFlo or PB Blaster. I did push the pistons out with grease through the bleeder valve. Trying to remember if I spraying brake cleaner before I yanked out the seal.

[CatatonicBug]

Since the pistons were frozen, I would definitely recommend a rebuild kit. Like Fred said, cheap insurance. Do it once, while you have it apart, and you won't have to mess with them again for a LONG time. If you did not remove the rubber ring, you would be surprised how much gold-colored crud gets collected in that groove. A stiff toothbrush and a tiny screwdriver were the tools I used to clean that groove out.