XT M8000 Bleed Issue

fatboyonabike

Eats Squid
If you get even the slightest amount of oil on the caliper, it’s a thorough clean either way. Also, business cards are super waxy. Use inside out cereal box cardboard, amateur.
I give up...you win, yoor the best!
OP, just get Moorsy to come around and do it, any other way will most likely be wrong
 
Reactions: Zaf

moorey

I'm full, couldn't eat another dick
I give up...you win, yoor the best!
OP, just get Moorsy to come around and do it, any other way will most likely be wrong
Thank you.

Also, wash the sand out of your vagina. I’m the first to point out my own stupidity, mistakes and ineptitudes. Don’t cry if I also point out yours :p
 

ashes_mtb

Likes Dirt
During bled...Lever all the way out, servo wave all way in? (Reset reach, and screw out servo wave after finishing)
After removing funnel and replacing reservoir screw, apply a bit of pressure on syringe at caliper end and close off bleed nipple with pressure still being applied.
Winning.

That bit of pressure with the reservoir screw in was the ticket. Has a slight amount of pressure at the lever afterwards, and when I reinstalled the funnel a stack of air came out and she bled like normal. Lever is hard as now.

Thanks mate (and everyone else for input).

Now I don't think there's enough isopropyl in the world to clean this mess up but at least I can get on with building this thing now.
 

moorey

I'm full, couldn't eat another dick
Winning.

That bit of pressure with the reservoir screw in was the ticket. Has a slight amount of pressure at the lever afterwards, and when I reinstalled the funnel a stack of air came out and she bled like normal. Lever is hard as now.

Thanks mate (and everyone else for input).

Now I don't think there's enough isopropyl in the world to clean this mess up but at least I can get on with building this thing now.
You do end up with a bees dick of positive pressure in there, so always have your syringe on the caliper bleed nipple and release any pressure back into there during next bleed, rather than removing funnel port first. If not already doing so, after funnel is on, suck a little oil back into syringe to remove air from bleed nipple before pushing oil back up. Sounds like the bleeding obvious...pun intended...but many people seem not to, and immediately push a little air straight into the caliper.
 

EsPeGe

Likes Dirt
Had to install a new hose for my rear XT brake and am having a hell of a time getting them going. Still getting no lever feel or movement at the piston.

Barb and olive are in good and no leaks.

Ditto at the banjo, remembered the o-rings and there's no leaks there.

Have pushed oil up from bottom to top with a syringe about 6 times. Oil comes up into the funnel with no air bubbles.

Also tried just a gravity bleed from the funnel down. Both with just gravity and also pumping the lever.

No air bubbles coming out in the funnel when I pump the levers with bottom bleed point shut.

Got me beat - any suggestions?
Hey man another idea that might help, the pistons may be seized up a bit. Try using something like Isopropyl alcohol or brake cleaner with one of those long thin hose attachments to get it right into the space around the pistons. Then use a cotton bud with a small amount of brake fluid and run it around the piston. Capillary action will suck it in and should help un-seize the pistons. Then I'd give it another good clean with isopropyl alcohol before putting the pads back in. I've found this has loosened pistons on my XT M8000's and made them a lot more consistent.
 

The Duckmeister

Eats Squid
Then use a cotton bud with a small amount of brake fluid and run it around the piston. Capillary action will suck it in and should help un-seize the pistons.
Just an extra detail on this point, make sure the fluid used for piston lubrication is the same as what the brake is filled with. If it's a mineral oil system, Shimano, Magura, Tektro/TRP etc, use mineral oil, preferably the correct blend for the specific brake brand; if it's a DOT system - SRAM, Hope, Formula etc, use DOT fluid to lube the pistons.
 

The Duckmeister

Eats Squid
During bled...Lever all the way out, servo wave all way in? (Reset reach, and screw out servo wave after finishing)
ServoWave is a linkage between the lever and master piston pushrod; it's not independently adjustable, but does adjust a bit as
a side effect of stroke adjustment. Reach adjust moves only the lever and has no effect on any other part of the system.

When bleeding, fully retract the stroke adjust screw to maximise master cylinder volume (the adjust screw works by advancing the master piston down the bore; it is subtle, but not quite as ineffective as some critics would have you believe). Pulling a bit of vacuum pressure with the bleed syringe will help suck air out that might otherwise just be pushed into corners; a combination of positive and vacuum pressure is essential if the caliper is dry, because that's the most convoluted plumbing & most likely to trap air. Bleed the brake with both upward and downward oil flow, positive and negative pressure from both syringe and lever. Close the caliper port, refit the pads & wheel, and with the cup still connected and open (basically an extension reservoir), pump the brake to set pad clearance.and fill the plumbing. Remove cup & fit the reservoir plug. Adjust stroke screw to set the brake feel, then set the reach.
 

moorey

I'm full, couldn't eat another dick
I can’t tell if you’re agreeing, disagreeing or elaborating....
Either way, after many hundreds of bleeds I’ve worked out the most reliable method for me that gives me the best lever feel....even if I don’t explain it well or properly.
 
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