Mountain Bike Reviews Forum banner
Cancel
Create thread New Forums

XTR Trail Brake Issue

Jump to Latest
1 - 12 of 12 Posts

Salespunk

· Well-known member
Joined
·
7,327 Posts
Discussion starter · #1 ·
I have a brand new set of XTR M9000 that I am having problems with. The first pull the brakes will almost hit the bars and if I quickly release and pull again they are perfect. If I wait 2 seconds it resets and the lever will come close to the bar again. When I pull the bleed screw in the lever I can actually see the brake fluid change positions between lever pulls confirming that something somewhere is expanding and contracting beyond just the lever movement. Both brakes have the exact same issue and came that way from the factory. I have bled them several times from lever to caliper and caliper to lever, but nothing ever changes it at all. I even had a friend bleed them as well in case I was missing something, but no dice. No such problems from any of my old style XTR/XT or Saint brakes having setup and maintained 10+ sets over the last few years.

Not my first time at the rodeo, but I cannot figure this one out. Anyone have a similar issue or ideas on what is going on? It is driving me insane:madman::madman::madman:
 
#2 ·
Had a new m615 brake do this, check and make sure the line fittings are seating properly. I found one that the olive was too far down the line so too much line had gotten smashed inside or line was held at an angle so olive compressed at an angle. Had to shorten it anyway, so I just shortened it and everything was fine.

Also if the fittings aren't tight enough they will suck in air. So check that first. Doesn't matter the model of brakes, if the lines aren't sealing at the levers (less of a chance in xtr calipers due to design) or calipers, you'll never get them working right.
 
#3 ·
Did you cut the hoses?
If so, did you use new fittings?
If you are certain that you got all the air out of the calipers when you bled, check the hoses.
Make sure the banjo fittings are snug and make sure that the lines aren't damaged at the banjo and lever connection.
Shimano calipers do an excellent job of trapping air.
If your hoses are fine and you think you got all the air out of the caliper with whatever bleed method you used, you may need to cycle the pistons during the bleed process.
I like to cycle the pistons during the initial bleed and set up anyways.
Don't reset the pistons before the bleed process.
Instead, reset the pistons with the caliper bleed port open and with the syringe/hose/baggie + tubing/whatever you are using connected to the bleed fitting and with the funnel connected to the lever.
If you see bubbles when you reset the pistons, you have likely found your problem.
Push some fluid and move and reset pistons a few times until you are 100% certain you have an air free caliper.
Sometimes resetting the pistons prior to bleeding the caliper will still leave air in the caliper.
Best to have the caliper oriented vertically with the bleed port near the top-hanging the bike on a stand at the fork/downtube junction does wonders for orientating calipers so that air finds a way out.
Otherwise, removing the caliper from the frame can help too.
 
#5 ·
I'd try and push both pistons out and cycle them a few times, sometimes bubbles hide there, bleed, test. Odd thing is that both are doing the same..

I've been using Shimano disk brakes since 2002, swear by them reliability wise. However, I've installed a few (including my own) new XTR's 9020 trail that had issues, mainly the right piston won't retract completely. Pushing it out and lubing the piston alleviated the issue a bit, but not completely, piston just wont retract fully. The rear brake changes contact point, lever will harden or contact point will be sooner upon consecutive feathering pulls. Can't replicate it while not riding. The damn thing almost make me crap my shorts, as I was riding down communication breakdown in Sandy Ridge, OR. I was feathering the brake, and in a left turn it just engaged sooner, causing the rear tire to skid almost making me hit a tree at full blast in a sideways drift. Could have been easily a vacation ender.

Bled the thing when I returned home, but haven't been able to fully test it. I've been itching to part with them and give a shot to the new Guides, but damn DOT fluid..

We'll see, if they don't behave, will deal with Shimano warranty..
 
Save
Reply Quote Like Like
#6 ·
Ive had lots of issues with my m9020 brakes same as mentioned above. Ive bled them tightened all the fittings sat on the phone with warranty taken them to 3 different shops and so on. Talked to shimano again they claim its not a warranty issue... So I guess an expensive set of brakes is going in the trash and being replaced with another set of expensive brakes from a company that stands by their product.:madman::madman::madmax:
 
#9 ·
I installed (and had to bleed due to internal routing) my M987 (pretty much same as M9000) XTR two days ago and I got the "lever pull" you were describing.

I was bleeding the brake like an avid/formula brake, due to having good results with that system and how it removes air bubbles at the ends of the system (caliper and lever). I thought I had done a good job of it, when I realized that given the position of the bike, the fluid was indeed running from the caliper up to the brake lever, but that due to the bleed nipple on the opposite side of the caliper as the hydro-line, that some air bubbles were most likely stuck at the far end of the caliper, and due to the caliper sitting higher than the brake line, which follows the chainstay, those bubbles wouldn't work themselves out using this technique. So I rotated the frame to nearly vertical, so those bubbles would have to travel out of the caliper and along the hydro lines to the lever.

Rebleeding in that position did it. Also, be sure to pump the lever to work any bubbles out there. I find the avid/formula technique is very good at removing bubbles at the ends of the system (the pressurize/pull method) and the formula/avid bleed adapter screws onto the shimano levers perfectly.
 
Save
Reply Quote Like Like
#11 ·
Well, good, but "pumping" as you described, is classic air-in-the-lines.
 
Save
Reply Quote Like Like
1 - 12 of 12 Posts
About this Discussion
11 Replies
9 Participants
Last post:
shrub1
Mountain Bike Reviews Forum
posts
16M
members
534K
Since
1990
A forum community dedicated to Mountain Bike owners and enthusiasts. Come join the discussion about bike parts, components, deals, performance, modifications, classifieds, trails, troubleshooting, maintenance, and more!
Full Forum Listing
Explore Our Forums
General Discussion Downhill - Freeride California - Norcal Shocks and Suspension Passion