Brake fluid seepage

[Guest]

Last year, I rebuilt the brakes and all brake lines, front and rear. Brake lines were purchased from Z1, along with banjo bolts. Filled up with DOT5 fluid. Performance was great, 2 fingers on the front brake all that was needed.

Last week, the front brake lever started to feel spongy, getting worse to the point that the lever would almost hit the grip. Checking the master cylinder, I found the fluid almost gone. Topped it off, tied back the lever, and it's firmed up just fine. But checking over the lines, there is a bit of seepage at the MC banjo, the 1 to 2 junction under the triple clamp, and the left side caliper. Just a minor amount, not enough to even notice, but obviously a problem. All banjo bolts are tight, along with the hose to banjo joints.

I reused most of the copper washers at the banjos, as folks seemed to advise that was OK. There were no instructions with the Z1 lines and banjos; was I supposed to use teflon tape or other sealant when assembling the banjos to the hoses? Be a PITA to redo all of it, but it IS the brakes, so want to get it 100%.

Advise appreciated.

[Cipher]

If fluid seeps out air seeps in yes>?

Fix the seeping joint and flush bleed.

[Nessism]

I put Goodrich lines purchased at Z1 on one bike and getting the banjo fitting to seal to the hoses took a LOT of tightening torque because they use a flare fitting interface. Got it eventually but I was surprised by how tight I had to make them.

When working with brake lines I always use new crush washers. I'm surprised anyone would recommend recycling those seals since they are cheap yet critical.

[mmattockx]

Last year, I rebuilt the brakes and all brake lines, front and rear. Brake lines were purchased from Z1, along with banjo bolts. Filled up with DOT5 fluid.

1) Was everything you used compatible with DOT5 fluid?
2) Did you torque all the connections as per the service manual?


Mark

[hillsy]

Whilst it is generally good practice to use new crush washers every time, I have re-used old ones on occasion. You need to torque the banjo bolts up until they stop leaking.

One question though - are you certain you have a crush washer on each side of each banjo fitting?

[sailorman1617]

I don't specifically know that everything's DOT5 compatible; but I did a lot of forum searches, finding many recommending making the switch to avoid the moisture problems of DOT3.

I normally torque everything, but I'll recheck to be sure. I'll need to disassemble everything to replace the crush washers anyway, so will be sure to then.

Yes, I do have a crush washer on both sides of all banjos.

I checked the hose to banjo connections and was able to get a few a bit tighter. Hopefully will help.

Thanks for the replies.

[nastyjones]

I've re-used crush washers but first since they're so soft, I drag them across my file a few times, seems to help make sure they are flat.

[TxGSrider]

Id try retourqing the banjo bolts, and if that didn't work Id go to the auto parts store and spend a few cents on some new crush washers.

As for the DOT 5, the issues Ive heard with it is it 1) isn't as slippery as the conventional DOT 3 & 4 and, 2) can cause the seals to swell in the calipers. The combination of these two things can make the brake pistons harder to expand and retract and they tend to drag on the rotors. I'd stick with the DOT 3 or 4.

[Nessism]

DOT 5 is NOT compatible with normal DOT 3/4 fluid. Before switching to DOT 5 it's strongly advised to fully tear down and wash out both the master cylinder and calipers, and replace the brake lines.

[sailorman1617]

I completely rebuilt both the front and rear brake systems; master cylinders, calipers, lines and banjos. So there was no old fluid left in the system (it had turned to gunk anyway).

I switched to DOT5 on the basis of recommendations on the forum. Was this a bad decision? One downside is that DOT5 is more difficult to find. Ed, what's your opinion? I'd have to disassemble and flush the entire system to go back to DOT3, but if there's a reason to do so, I'd tackle it when I replace the crush washers.

[Nessism]

At this point I wouldn't go back, just fix the leaks. Again, if you are using Goodrich lines with the bolt on banjo fittings you need to make those attachments very tight or they won't seal. You need to pinpoint the source of the leakage first and then take the appropriate action. If the banjo attachment to the object is leaking I'd get new crush washers and go from there.

[Cipher]

yes new washers or heat and anneal the old ones
torqing an already flattened gasketing surface invits stripping of parts without ever fixing the leak