M985 XTR brakes + Jagwire Hyflow = Trouble bleeding, any ideas?
I've bled plenty of brakes before (both bike and car), but these have me stumped. I had leaking Shimano lines so i replaced them with the Jagwire Hyflow lines.
I'm currently dealing with just the front brake, which is basically a straight shot for the line. I've bled these the Shimano way (http://techdocs.shimano.com/media/te...9830710606.pdf). I bought the Bleed Cycles kit off ebay and i've been pushing fluid back and forth with that. I suspect the air is trapped in the caliper, but raising the bleed nipple to the top and bleeding like that hasn't worked so far.
Any other tips or tricks for me to try? I was thinking of taking the whole setup off the bike and hanging it with the caliper at the top, then pushing fluid up from the lever...but i don't know if there's a potential to damage any seals by pushing fluid in that direction. Help!
Wound up getting it decent, so i took it out on a long ride. Afterwards i bled it again and it's at about 99% now. I'll keep riding it and try again in a few weeks...but for the time being, it's good. Thanks!
I have never had to have the caliper up above the master cylinder / lever - really should not make any difference. As long as everything is sealed it should be fine.
Certain you dont have a torn seal in one of the pistons (no sign of leakage?)
No leakage onto the pads that i've noticed, but i'll keep an eye out!
My experience with exactly the same setup is that the Hyflow seals at the caliper can get in the way of proper oil flow. With out any oil in my system, I had a hard time pushing or pulling air through my system. After fiddli g with the setup, I got them to work as they should.
It might not be what you are experience but my main symptom was extremelly slow pad retraction speed and it was very hard to bleed
I noticed as i was assembling them that that was an odd design. They really ought to come up with something different, or just use an o-ring in a groove like shimano did. I've seen similar systems use much fancier designs.
At any rate, i bled them again and i'm happy with the feel..
Last edited by Porch; 06-19-2013 at 08:45 PM.
Actually, i've still got a weird issue. The brakes are completely bled and they feel good, but if i apply the brakes again too quickly they lock up much more quickly in the stroke. It leaves a really inconsistent feel to the brakes that's really frustrating.
I think this is related to the extremely slow retraction of the pistons, which is due to those o-rings.
I'm going to cut out some of the inner part of the o-rings and re-bleed.
Last edited by Porch; 06-19-2013 at 08:01 PM.
Old timer's trick because I am old. Tap on the caliper and lever while you are bleeding, drunk woodpecker style. That will help vibrate any stuck air bubbles caught up in there.
Haha, not necessarily an old-timer's trick I did tap on the caliper and the lever and everything in-between.
To be honest i'm really confident that i have all the air out. The Hyflow lines for the XTR's come with aluminum washers for the banjo fitting that have a rubber seal on their inner circumference. As part of this seal there's a thinner rubber part that rests on the the thru-bolt of the banjo fitting. I guess what they were trying to accomplish is a way of centering the washer while allowing the rubber to "flap" as fluid was passing by. What i think is happening is the flap is slowing down the fluid, causing the slow piston retraction that someone else mentioned. It's a really crummy design!
I think if i carefully cut out portions of this inner-inner-seal it will allow the fluid to flow normally and make bleeding easier. I'm disappointed that this is necessary, though.
Well, i felt the need to prove to you all that i'm not an idiot, so i made my modification to the inner washer/seal.
Here's a pic of what i did:
As you can see the rubber normally makes direct contact with the banjo bolt.
I put the modified washer on the inside only (caliper side) and the improvement was exactly what i hoped. Bleeding was much easier, the pistons return instantly, and the lever doesn't get the "pump up" that it was getting before (where the lever would have a normal amount of stroke the first time and then if pumped would have almost zero stroke on the second stroke).
Well, great news! I sent an email to Jagwire and they responded that they have already fixed this issue. I think i just got an old version of the kit. Jagwire is sending me the new version of the kit. I'm really impressed with their customer service...highly recommend these guys!
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