Shimano XT M775 Brake Bleed « Singletrack Forum

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Shimano XT M775 Brake Bleed

37 posts & 16 voices | Started 1 year ago by Oscillate Wildly | Latest reply from bigyinn

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Oscillate Wildly - Member

how easy is it to do so? this is one thing ive never attempted to do and to be quite honest it scares me

am i fretting over an easy job? also i have seen the bleed kits on ebay for about 8 quid, is this really enough to bleed a set of brakes?

i really should do them, as the fluid is over a year old, and although they are performing like the best ive ever owned, i know at some point im going to have to attempt it

so any step by step instruction guides out there? any help really appreciated, id love to combat this without paying someone to do it, ive saved a small fortune recently doing a few jobs myself, so would like to continue the trend

fannnnnnnks!

Posted 1 year ago #
rockthreegozy - Member

If you plan on staying with Shimano, the 1l container of fluid at £15 is much better value than the small one.

Syringe and tubing is all you need to complete the kit- £3 or so.

Posted 1 year ago #
thinboy70 - Member

I recently cut down the hoses on my Saint m810 and thus had to bleed them. Was a piece of piss!

You should not freak out about it. If your considering paying a mechanic to do it anyway, give it a go first and if you balls it up (which I very much doubt) then let the mechanic sort it. At least you will know.

Search Youtube as there are loads of videos on how to do it.

Posted 1 year ago #
iainc - Member

Shimano mineral oil doesn't take up moisture like Dot oil, so if they are working fine leave for now......If it ain't broke.....

oh, and when you do bleed them, advice as above about online guides etc. I have always found that bleeding bottom up with a big syringe with about 50-75ml of new fluid works best. I just hang a little tub under the horizontal reservoir and really flood the whole system.

Posted 1 year ago #
Macavity - Member

http://techdocs.shimano.com/media/techdocs/content/cycle/SI/SI_0040A_001/SI_0040A_001_En_v1_m56577569830615981.pdf

http://cycle.shimano-eu.com/publish/content/global_cycle/en/nl/index/tech_support/tech__videos.html

http://cycle.shimano-eu.com/publish/content/global_cycle/en/nl/index/tech_support/tech_tips.download.-Par50rparsys-0005-downloadFile.html/Resetting%20Disc%20Brake%20Pistons.pdf

http://cycle.shimano-eu.com/publish/content/global_cycle/en/nl/index/tech_support/tech_tips.download.-Par50rparsys-0004-downloadFile.html/Brake%20Hose%20Installation.pdf

Posted 1 year ago #
Ecky-Thump - Member

You don't need to do it if they're working fine. I'd only bother if you notice excessive lever travel or deteriorating performance.

Yes, the XT is probably about as easy a brake as you will find to bleed. First time I did mine was a couple of months ago. It took about 10 minutes to do both ends and was so easy to do that I did the other bike too just for good measure. Bottom up.
1. Twist master cylinder to horizontal, position something to catch spillage. Remove cover.
2. 6" of car washer tube attached to syringe. Fill with mineral oil. Fit to caliper bleed nut. Slacken nut. Squirt >30ml through and you should hear any air bubbles fizzing out as the fluid spills out of the master cylinder. Tighten bleed nut.
3. Refit master cylinder cover. Job done.

I hung a carrier bag containing absorband material (eg paper shredder waste) from the bars to catch the spillage.
Costs:
60ml Syrige - free from local vet
washer tube - pennies
Halfords LHM fluid - £10 a litre

Compare and contrast with the aggrovation I had trying to bleed Hayes Strokers. Gave up and took 'em to bike shop. They managed to get some improvement after much cursing and swearing. Sold 'em on Ebay shortly after. XT on both bikes now

Posted 1 year ago #
flyingmonkeycorps - Member

I found bottom up and top down both worked equally well, as long as you do it properly!

Top down:

1. Spanner on bleed nipple (ring spanner is MUCH easier)
2. Washer tube from nipple to container - I use a sandwich bag cable tied on
3. Get the lever / reservoir horizontal
4. Unbolt the cap off the reservoir and take out the diaphragm. This is the trickiest bit if you overtighten the bolts as they're easy to round.
5. Loosen nipple 1/8 of a turnish and pull in the lever about 3/4 of the way
6. Tighten nipple and release lever
7. Repeat 5 & 6 until there are no air bubbles coming out of the caliper. As you're doing this keep topping up the fluid in the reservoir - try not to let it get below half full. If it's empty, you're pulling air through the system!
8. Top up the reservoir and refit the diaphragm and cap. Make sure you have a rag to soak up the inevitable overflow.
9. Job is a goodun. If you have one, use the plastic spacer to space the pistons out, saves the risk of getting fluid on your pads.

Posted 1 year ago #
JonR - Member

Its easy. You can simply make the brake lever horizontal and pump the lever to see if any air comes up and then top up the reservoir for a 2 minute fix, bleed top down where you fix a tube to the bleed nut and then pump fluid through the system with the lever or bleed bottom up as described above.

Posted 1 year ago #
scruff - Member

Is LHM really the same visocity ? I've read reports its a bit thicker so can slow your sytem down a bit.

Posted 1 year ago #
Oscillate Wildly - Member

cheers guys, really appreciated the advice and help, good to hear it really doesnt sound a balls ache, i wish i could watch somebody do one, just to get the jist....any body fancy doing me a video

seriously those step by guides look pretty sweet!

Posted 1 year ago #
flyingmonkeycorps - Member

As soon as you try it you'll be laughing, it really is easy. I'm a ham fisted oaf and I can do it!

Posted 1 year ago #
bigyinn - Member

Only ever used LHM in about 3 different types of Shimano hydraulics, never had an issue. Its mineral oil, its not used for damping or the like, never heard it make things slower before! You're only using it as a compressible fluid, theres nothing to really slow it down.

Posted 1 year ago #
Oscillate Wildly - Member

cheers flyingmonkeycorps, ill give it a shot! sure ill be fine after the first attempt and no doubt failure!

Posted 1 year ago #
Oscillate Wildly - Member

just one more quickie guys - where can i get this tubing i need? also how do i know which size will fit the bleed nipple? any links? gonna have a crack at it this weekend

Posted 1 year ago #
squiff - Member

4mm pipe, b&q about £1 for a meter

Posted 1 year ago #
ahwiles - Member

take the pads out first.

put them in the spare bedroom.

nail the door shut.

you aren't allowed back into that room until you've finished messing around with your brakes, cleaned everything, and washed your hands.

give your discs a clean while you're at it.

Posted 1 year ago #
flyingmonkeycorps - Member

Or screenwash hose from Halfords will work too. But is probably a bit more expensive.

If you're doing bottom to top with a syringe, Cartridge World type places will probably give you one for nowt.

Posted 1 year ago #
Oscillate Wildly - Member

thanks guys! will get some from halfords or b&q! 4mm is what im after then!

im gonna do it bottom up i think, i can get hold of some 75ml syringes no problem....

does the syringe force really push the oil through an up?? just thinking as its got to travel upwards towards the brake? how does it push all the old one out? i know its probably simple but i cant make logical sense to it haha

Posted 1 year ago #
Ecky-Thump - Member

take the pads out first.
put them in the spare bedroom.
nail the door shut.

I must enjoy living on the edge in a surf-Matt-esque state of awsomeness... 'cos I didn't even take the wheels out, never mind the pads. Was just extremely careful and held the tube firmly to the bleed nipple whilst syringing.
Yes, in retrospect, a few risk mitigation plans might have been appropriate.

Posted 1 year ago #
flyingmonkeycorps - Member

If you do it bottom up the old fluid comes out the open reservoir, usually all over your bars, grips, disc, pads, floor, tea, cat...

Posted 1 year ago #
Ecky-Thump - Member

does the syringe force really push the oil through an up??

Yes. A syringe will generate more that enough pressure to purge the system. Press slowly, firmly and smoothly. I would assume the rate of flow through the constriction of the hose is the only limiting factor, and the one that would cause the only forseeable mishap; blowing the hose off the nipple.

Posted 1 year ago #
Oscillate Wildly - Member

mint, thanks guys...

is there always about 30ml in the reservoir? as you said to squirt 30ml through the caliper, im guessing that when you have put in 30ml roughly it will have replaced all the old oil in there?

i guess the advantage of doing it this way, means no air bubbles can occur? as with doing it top down you are looking for air bubbles at the caliper end?

Posted 1 year ago #
scruff - Member

Aquarium tubing is good aswell.

Posted 1 year ago #
Ecky-Thump - Member

The 30 ml came from my observation that the colour of the fluid in the master cylinder reservoir began to change noticably at somewhere between 10 and 20ml of syringing. (LHM is a different colour to Shimano oil).
30ml therfore represented a decent purging.

Posted 1 year ago #
zangolin - Member

Video of how to bleed Shimano brakes from pinkbike
http://www.pinkbike.com/news/technical-tuesday-shimano-brake-bleed-2010.html

Posted 1 year ago #
Oscillate Wildly - Member

thanks thanks and thanks again guys, im actually looking forward to trying it now!

if it goes tits up ill have no brakes or at least only one brake for a week

video looks good thanks zangolin, though im gonna try it the syring way down/up first it!

Posted 1 year ago #
ahwiles - Member

i got all sorts of funny looks asking for a syringe in various pharmacists around sheffield.

in the end i got mine of e-bay - 50ml is plenty big enough.

(i bought 2, they're cheap, the other syringe is good for hoovering any excess fluid from the open reservoir)

it can be a little tricky getting the hose/tube to fit over the nipple/syringe - especially if the fun police have sent you to the cellar/shed/garage where it's cold.

the night before you want to bleed the brake; dunk one end of the hose in a cup of hottish water - and fit it to the nipple, let it cool, then remove it, then fit the other end to the syringe.

leave it to dry overnight.

Posted 1 year ago #
Oscillate Wildly - Member

one last quickie i promise :- ref the tubing

ive seen some on halfords, but there are two sizes

http://www.halfords.com/webapp/wcs/stores/servlet/SearchCmd?srch=washer+tubing&x=0&y=0&action=search&storeId=10001&catalogId=10151&langId=-1

which of the two will i need for the tubing for the bleed? gonna pick some up after work if these are suitable

cheers!

Posted 1 year ago #
thisisnotaspoon - Member

n.b. if you go bottom up,

1) do at least one or two pumps of the lever to dispell any old fluid air in the master cylinder before you finish.

2) air can get trapped under the bleed nipple and forcing fluid in wont move this air bubble, so do a couple of squeezes from the top down before you start.

Posted 1 year ago #
zangolin - Member

Tubing - another good source/alternative is silicon fuel tubing from a model RC shop - cheap as chips + easy to fit onto bleed nipples

Posted 1 year ago #
Oscillate Wildly - Member

zangolin do you know where i can buy some online kind sir?

want some thats fits decently so wont be sploshing oil every where

Posted 1 year ago #
zackaustin - Member

after similar searching, i found a link on the mighty ebay.....It would appear that this is the very boy you have been looking for .. with shimano fluid: http://cgi.ebay.co.uk/Shimano-Disc-Brake-Bleed-Kit-Deore-SLX-XT-Saint-XTR-/170587479071?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item27b7ce5c1f#ht_500wt_1156

without:
http://cgi.ebay.co.uk/Shimano-Deore-XT-SLX-Saint-compatible-brake-bleed-kit-/170583599220?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item27b7932874#ht_2761wt_94

I got the one without fluid ... but for £3 more, kinda wish id have got it with. LHM works, but you can tell the difference in the fluids... it just feels ...well ...thicker.

with dot 5.1, will this work on hope m4/mini/etc...?

now, who on here knows about fox 36s....?

zack

Posted 1 year ago #
bigyinn - Member

Fluid is non-compressible, so how can it feel any different? LHM is non-compressible fluid the same as Shimano Mineral oil, the only difference is the colour. It won't "feel" any different regardless of which fluid you use.

Posted 1 year ago #
ahwiles - Member

different viscosity? - just a guess mind...

Posted 1 year ago #
bigyinn - Member

Why would the minimal difference in viscocity make any difference? You're just compressing it, you're not pushing it should any valving or the like.

Posted 1 year ago #