Calipers leak - this doesn't make sense

[randy]

I did a full rebuild on my brake systems, M/C, S/S lines, Caliper re-seal - the works. All new rubber parts. New pistons, too.

So tell me, why is it that my front calipers weep fluid? Not a lot, but after a week of sitting, there is a drop of fluid on the rim. Both sides. I could understand one side or the other, but both? It's definitely coming from the bore, not the bleeder.

Got the re-seal kits from Parts 'n' More. Anyone have trouble with these kits before? During the re-build, the pistons were nice and smooth and snug in their seals, not loose at all.

By the way, the rear is fine. Same seals, same piston. (79F)

?? help, guys??

Randy

[Snow]

Perhaps you put the seals in backwards? If I remember correctly there is in inner side and an outer side on the rubber seals, but I could be wrong.

[randy]

Funny, I thought the seals are square. Can anyone verify this before I disassemble my calipers?

Randy

[Geezer]

I've never heard of directional caliper piston seals in all the years that I've been turning wrenches.

Where is is weeping? My guess is it's leaking around the banjo bolt because the sealing washers are hardened.

Geezer

[randy]

Thanks for the sanity check, Geezer. Thought I was nuts for a minute there. Anyway, they are weeping past the piston seals. The banjo washers are new. The bleeder screws are new speed types. All is dry at the banjos and bleeders, weeping is definitely from the piston seals ON BOTH!

P.S. they didn't leak with the 25 yr old seals. Then again, the hoses were 25 yrs old, too!

So I'm all new rubber from lever to pistons and I'm pissed that I have to tear 'em down again.

"it could be worse - -it could be raining" - Marty Feldman

Help.

Randy

[Geezer]

Originally posted by randy
Thanks for the sanity check, Geezer. Thought I was nuts for a minute there. Anyway, they are weeping past the piston seals. The banjo washers are new. The bleeder screws are new speed types. All is dry at the banjos and bleeders, weeping is definitely from the piston seals ON BOTH!

P.S. they didn't leak with the 25 yr old seals. Then again, the hoses were 25 yrs old, too!

So I'm all new rubber from lever to pistons and I'm pissed that I have to tear 'em down again.

"it could be worse - -it could be raining" - Marty Feldman

Odds are something in there was a little corroded. Disk break calipers aren’t supposed to be honed, so I scrub them out with brake cleaner and a copper pot scrubber. Then I use a seal pick to (lightly) scrape down the inside of the seal groove. Providing that nothing is scratched, it shouldn't leak at all but it looks like it's time to tear into it again.

Funny thing is that I've disassembled and cleaned bunches of calipers over the years and reused the old seals without a leak. Your mileage may vary. ;o)

Geezer

[randy]

I have also re-used seals in the past. On my 76 KZ400, the seal was out of production and I had to re-use it. Went fine without a hitch, so I must have some spooge in the grooves that I overlooked. I guess I'm working too fast on too many things at once. Sometimes you have to slow down to make progress!

Thanks for the heads-up!

Randy