Just recently on my 748 the brakes have started to fell really spongey with the lever travelling right back to the stop. I've bled the system several times (in various different ways) with no joy but noticed the nipples on both callipers and the m/c were weeping. I've since replaced them all and the lever has got better (but still not great) pressure but the nipples on the callipers are still weeping. I've lowered the fluid level in the reservoir to the min mark so not overfilled. I have the brembo P4 callipers (65mm spacing), braided lines and a brembo 19x18 m/c. The pistons in the callipers are all moving freely and equally. Any ideas what the problem could be? Don't want to result to PTFE tape!!!!
Are you saying the bleed nipples are leaking or the banjo bolts with the copper or soft aluminium washers , just were you say use ptfe tape , the bleed nipples rely on the cone face bedding into the counter sunk face on the caliper , the thread doesn't do the sealing . If it is the banjos that weep sometimes you have to work the bolt back and to , you will find you will get more of a turn on the spanner as the banjo bolt cuts into the soft faces of the washers , get this on car calipers all the time ... coroded sealing faces on the calipers , a bit of 'back and to' action normally sorts it Just a thought .....you haven't over tightened the bleed nipples and cracked the housings , probably not but just be sure .
Yes it the bleed nipples that are leaking, banjos are fine. To my knowledge they haven't been over tightened but clearly the cone isn't seated right, even with new screws! Seems strange how it's happened to all three nipples at once.
The bleed nipples the correct 'cut' , debris in the drillings , corrosion / pits in the caliper sealing face ...
Dry it off then cable tie the lever back and watch where fluid leaks, I take it you used new copper washers. And was already said" don't use ptfe " the washers do the sealing not the thread.
have tied the lever back and still weeping so can't be seated properly. Just seems strange how its happened on both callipers. could they have been damaged by over tightening? If so, is it fixable?
bought some nice stainless nips offa ebay that didnt seat properly. contacted the seller a week or so later (after fitting) and she was really apologetic saying her supplier had sent out a bad batch and she had had numerous. refunded straight away. point is it is possible that the machining of the nips is no good
cheers fellas. idrinkbeer - its weeping from the bleed nipple not where the banjo joins the calliper. Chizel - hopefully thats the case, i'll try and get another set.
I've had the same thing on my '94 750SS. I rebuilt the calipers completely and replaced the original knackered nipples with stainless ones from Hel. Both leaked spectacularly. Another set: same thing. Spoke to a mechanic who suggested that it could be that some crud from the rebuild and bleeding has worked its way down the threads and preventing the cones from sealing. He also suggested trying genuine brembo nipples rather than aftermarket stainless ones as they should at least be virtually guaranteed to have the correct profile to seat right. Waiting for them to come so I can test the theory! If not that then looks like calipers are damaged which would be a major PITA. Also, as mechanico suggested above, I had to nip up, release and retighten the new banjos a bit to get them to seal. That definitely worked for me. Mick..
Sounds exactly the same as me, the weeping is there with the new nipples but nowhere as bad and feel at the lever is good. and hasn't faded over the week. Who sells the genuine brembo nipples (M8) can only find aftermarket ones.
Got mine through local ducati service centre. Apparently bleed nipples are classed as a service item and not subject to the same nonsense as seals, pistons and the like (presumably as changing them doesn't require dismantling the caliper). Not picked them up yet so dunno what they're like. I'll report back... Mick..
Had the same problem after upgrading my front brake set up with completely new MC, lines, nipps the lot. I checked out the thread dimensions on the nipps and the tolerances where crap all over the place. Conclusion I came to nipps are mass produced and the tolerances vary a lot. I solved my problem with leakage by going through my nipps until I found one with a good fit.
So I performed nipple surgery today.. Genuine, new Brembo bleed screw on the left, stainless aftermarket one (pretty sure from Hel) on the right. Even with my photography skills (not!) you can clearly see the difference in the profile of the cone. Brembo one is shallower but comes to a finer point. I did both front calipers and the clutch. Early signs are good with no apparent leaks, though I'll leave it over night and see in the morning. If all good, I'll leave it under pressure for a bit and check then too. Certainly, the clutch has a much better feel now (I say "better" - heavy as hell on a Supersport), though I'll be honest and say the brakes still feel crap to me. Mick..
