Front caliper air leak

[Guest]

My '80 850 front brakes are fooling with my sanity.....

MC is rebuilt, steel lines installed, both calipers have new seals in them (by PO), caliper sliders lubed with brake lube.

The left caliper bleeds out fine, no air by end of process (using Mityvac).

The right caliper seems to be leaking air...i cannot get any vacuum to stay, and air continues to come out the bleeder (all new bleeders) with vacuum applied, even with bleeders closed. No fluid leak noted. That's the issue that has me twitching on the ground...air leak but no fluid leak.

I've done a search on this subject on the forum, and, while I learned lots more about brakes, no answer to my particular query was found.

[rustybronco]

I don't know if it pertains to your predicament, but you might want to try wrapping the bleeder threads with some teflon tape.

at least that's I've read.

[Runningdog]

Thanks, RB, that's a good idea...although, at this stage, I'm willing to sell family members for an answer....


Here I am 1/2 hour later, having teflon-taped the bleeding bleeder, and have successfully achieved pumpage....yahoo....thanks, man...

[rustybronco]

Glad it worked out for you! it's one of the not so useless tips I found on this board that stuck in the old gray matter just itching to be recalled one day.

[Jagir]

Is that teflon tape going to be a permanent fix?

[Runningdog]

I guess short of replacing the caliper, the teflon tape is a permanent resident.......I replaced all the bleeders, mere hours before taping.

I just checked the pressure..all good, lever is good'n'stiff, no flaccidity....I gotta stop right here.....

[Nessism]

Teflon tape is just so the mitivac doesn't suck false air into your bleeding tube, thus falsely indicating air is in the system. Once the nipple is tightened back down, the Teflon tape does nothing since the bleeder nipple seals when the taper on the bottom contacts the matching taper machined into the caliper body.

[Runningdog]

Actually, you are right, Nessism.......there was something hinky with my bleeders, as I could still suck air with the one bleeder tightened...new bleeders took care of that issue, but it still sucked air past the threads during Mityvac use. Once I applied the teflon to get the vacuum bleeding done, everything is back to normal.

Still haven't had a chance to try out the Russel lines yet, waiting for the Dyna coils and wires from Z1....hoping early this week.

[Dogma]

Because of this air leaking past the bleeder threads, I've taken to finishing a bleed the old fashioned way: by pumping the master and releasing pressure at the bleeder. I've been using the Mityvac just to pull a lot of fluid quickly. Say, when flushing, or filling a rebuilt system.

[Jagir]

Still haven't had a chance to try out the Russel lines yet, waiting for the Dyna coils and wires from Z1....hoping early this week.

If they are threaded, make sure you tighten them hard. I had a little brake fluid leak at the threads because i did not want to put too much torque on the banjo.

[Runningdog]

Yeah, Jagir, I noticed that....the rear weeped a bit at the caliper banjo, so a bit more twistage fixed it up.......in retrospect, I also should have replaced all the compression washers.....I know, I know, I'm bad....I'll order them this week..all 13 of them, do the whole bike.