XT M8000 Bleed Issue

moorey

Nothing is better than a tomato
So what's the fix for the wandering bite point ?
Bleed properly, pushing up, lever out, servo wave in...slight positive pressure in the system.

I can only assume this, as it be been running m8000’s on numerous bikes since 2015 and never suffered the issue

edit. Servo wave screwed mostly out after finishing bleed.
 
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moorey

Nothing is better than a tomato
That said, Oldest set pump up a bit on long hard descents. Always have, was a known issue they seemingly resolved. I’ve never worried about it, they’re just firmer in lever for a few seconds.
 

CHEWY

Eats Squid
Bleed properly, pushing up, lever out, servo wave in...slight positive pressure in the system.

I can only assume this, as it be been running m8000’s on numerous bikes since 2015 and never suffered the issue
You are probably right as the PO fitted the brakes to the bike which has internal routing and may not have bled them properly.
 

moorey

Nothing is better than a tomato
You are probably right as the PO fitted the brakes to the bike which has internal routing and may not have bled them properly.
It’s very possible...or just needs fresh oil. 775’s never had the issue, but 785 and 8000’s oil turns metallic grey after a lot of use and feels spongy. Only real fix is to push fresh stuff in.
 

Plankosaurus

Hydraulic Jack specialist
So what's the fix for the wandering bite point ?
The bleed up fix will take 5-10min and only uses a few ml of fluid. Worth a crack before going the full bleed.

Or buy avids, I hear they're far more reliable and much easier to bleed [/sarcasm]

Sent from my G8441 using Tapatalk
 

Scotty675

Likes Dirt
Have shimano brakes got harder to bleed?

I remember buying a bleed kit when I first upgraded a set of mtb brakes. They were m785s. I was expecting to fuck it right up.
Was as simple as fit brakes, cut lines to length, fit new olive and barb connect. Bleed was push some fluid up from caliper into cup till saw no bubbles. I never fluffed around bleeding levers. Always worked perfectly first time and only ever rebled to flush new fluid through.
 

Plankosaurus

Hydraulic Jack specialist
Have shimano brakes got harder to bleed?

I remember buying a bleed kit when I first upgraded a set of mtb brakes. They were m785s. I was expecting to fuck it right up.
Was as simple as fit brakes, cut lines to length, fit new olive and barb connect. Bleed was push some fluid up from caliper into cup till saw no bubbles. I never fluffed around bleeding levers. Always worked perfectly first time and only ever rebled to flush new fluid through.
That's what I've found 90% of the time, but I've had 3 levers over the last 6 years that have done the wandering thing and needed extra help. And the lever feel may be able to be firmed up a bit, maybe.

Sent from my G8441 using Tapatalk
 

Mattyp

Likes Dirt
Have shimano brakes got harder to bleed?

I remember buying a bleed kit when I first upgraded a set of mtb brakes. They were m785s. I was expecting to fuck it right up.
Was as simple as fit brakes, cut lines to length, fit new olive and barb connect. Bleed was push some fluid up from caliper into cup till saw no bubbles. I never fluffed around bleeding levers. Always worked perfectly first time and only ever rebled to flush new fluid through.
no theyre still just as easy, and to install a new set Is just a quick lever bleed fit, just fit bleed cup and flick the lever a few times with 20ml or so in the cup, afterall they are pre-bled from factory and you are only getting rid of any are that may have entered when you removed the hose for install.. for a full bleed i just pump and bleed out of the bleed nipple as per any conventional brake keeping the bleed cup full. once you have new fluid coming out the bottom, tap along the length of cable and flick the lever a few times to eliminate any bubbles trapped, rotate lever back 30degrees, rotate lever forward 30 degrees to release air from any pockets in the lever, remove cup. never had an issue on zee's or saints.
 
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Scotty675

Likes Dirt
Of the shimano brakes I've owned 785s, zee, 9020, 9100 never had any issues simple bleed and good to go. M8000 and 1 set of 9120s I've had issues and spent more time on lever bleed. The set of 9120s that I had dramas with I tried everything even a vacuum bleed as per maguras. Only fix was the new olive barb and connector. I don't think they are hard to bleed 95% of the time.
 

CHEWY

Eats Squid
The bleed up fix will take 5-10min and only uses a few ml of fluid. Worth a crack before going the full bleed.

Or buy avids, I hear they're far more reliable and much easier to bleed [/sarcasm]

Sent from my G8441 using Tapatalk
I've just done what I think Moorey said to do... reverse bled a little until overflowed out the top fill, put the plug back in keeping it completely full, then put a little positive pressure on syringe and tightened the bleed nipple.
They are M7000, not sure if they have the servo adjust etc. I just did it with my normal lever position...
 

CHEWY

Eats Squid
It’s very possible...or just needs fresh oil. 775’s never had the issue, but 785 and 8000’s oil turns metallic grey after a lot of use and feels spongy. Only real fix is to push fresh stuff in.
I've got 785's on another bike, they could do with being a bit spongy they are brutally grabby.
 

moorey

Nothing is better than a tomato
I've got 785's on another bike, they could do with being a bit spongy they are brutally grabby.
Tried screwing the servo wave right in if not already?
I like the 785’s. Probably treated me better than m8000’s in the long run.
 

SummitFever

Eats Squid
This thread reminded me that I needed to swap the M9000 lever for the M9100 that I had on. This is a rear brake so I put the bike vertically in the stand so any air would come up to the master cylinder.

Just a regular bottom up bleed resulted in the variable bite point. Flicking the lever and then tapping the master cylinder repeatedly over the course of about 5 minutes had many little bubbles come up into the bleed funnel.

Once there were no more bubbles coming up I sealed things up and no more variable bite point.
 

The Duckmeister

Eats Squid
Bleed properly, pushing up, lever out, servo wave in...slight positive pressure in the system.
I told you before - changing the lever position does exactly nothing more than change the lever position; it is completely separate from the master piston position. Similarly, you can't twiddle the ServoWave; it's a linkage between the lever and the master piston pushrod. You can alter the master cylinder volume and stroke by adjusting the stroke screw - winding the screw in (on models where it is fitted) pushes the master piston down the bore, which then alters slave piston position/ pad clearance.

For maximum system volume, back the stroke adjust screw right out, bleed the brake, pump up to set clearance, then advance the stroke adjust to reduce play if desired ,THEN set lever position with the reach knob.
 

moorey

Nothing is better than a tomato
I told you before - changing the lever position does exactly nothing more than change the lever position; it is completely separate from the master piston position. Similarly, you can't twiddle the ServoWave; it's a linkage between the lever and the master piston pushrod. You can alter the master cylinder volume and stroke by adjusting the stroke screw - winding the screw in (on models where it is fitted) pushes the master piston down the bore, which then alters slave piston position/ pad clearance.

For maximum system volume, back the stroke adjust screw right out, bleed the brake, pump up to set clearance, then advance the stroke adjust to reduce play if desired ,THEN set lever position with the reach knob.
Fark, aren’t you cranky and pedantic tonight, mate.
I’ve bled more shimano brakes than MOST mechanics. I know what works for my brakes.
 
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