Shimano M785 XT hose shortening

BikeBen

Hi All

I'm about to install some SHimano XT (M785) disc brakes. I know the hoses will be too long and so once installed I'll need to shorten. My brakes didn't come with the little yellow hose clamp and spare olives. I know my mate has one of the yellow hose clamps and I was just about to order 2 Shimano universal olives. I did a quick Google and I think that the M785 has a different size hose? and in fact I need a BH-90 olive?

At the beginning of the Shimano tech doc (below) it seems to mention different sizes of connector.

http://techdocs.shimano.com/media/techd ... 750008.PDF

Is that right? Can anyone confirm any of that? Anyone shortened the hoses on their M785 let me know what they used?

Thanks very much

BikeBen

Quick update to anyone who is interested. I spoke to the mechanic at my LBS and he confirmed that the olives are different or in fact the olive itself is the same and the insert is a silver one not the gold one. They also seem quite hard to come by at the moment. I'd still like to hear from anyone who has found this out or has shortened hoses on M785.

Thanks.

.blitz

Attempted to shorten the hoses on some 575s in the way your linked document describes and it was an utter failure.

Despite carrying out the procedure in near-surgical conditions i.e. the kitchen I still managed to get some air into the system which even after a couple of bleeds is still not out.

Good luck

BikeBen

Thanks blitz

I've heard mixed things about that document. Some people seem OK with it but the general consensus seems to be that to be sure u really do need to bleed after.

benpinnick

Once you cut the hose down, you can remove the barbed inserts by cutting the hose down its length, and the olives are likewise reusable.

matt@theforce

I've shortened M535's and M785's and didn't have any trouble, the M535's needed a quick bleed afterwards but the M785's worked fine and still working great now (not bled)

BikeBen

Thanks for this. What did you do about the olives and inserts? I assume you got some with the M785 which you used? If so can you confirm they had the silver inserts rather than gold?

Thanks.

matt@theforce

Yes, mine came with spare Olive's/Inserts but I can't remember what colour they were

benpinnick

Iirc mine had silver ones.

clamps81

Mine came with spares, so I'll have a looksee tonight and try and grab a photo. Shortening hoses on sat, so provided I remember I'll let you know how I get on.

BikeBen

Thanks clamps81 that would be cool. Let me know how you get on with the shortening I;ll be doing it for the first in the coming weeks. I'm reasonably confident just one of those things I've not done before.

clamps81

Without a set of calipers to measure accurately I can't tell 100%, but my spare olive and insert look like the bh90 one, but that's purely from the colour of the insert. I would post a photo, but I couldn't get a good one because I was hauling my shopping out the back of the van at the same time and the phone didn't like the low lighting and wobbliness. I will try and grab some at the weekend if you still need confirmation.

Do the shimano tech docs provide any insight on this? They can be quite useful for part nos.

BikeBen

No worries Clamps, would still like to know how you get on shortening your hoses if that's OK?

The more I read and ask people stuff the more obvious its all becoming. For the M-785 brakes you can't use the Shimano Universal Olive (which in my opinion doesn't make it very universal, maybe it was universal when it first came out). You need the BH-90 Olive and insert which has the same olive but a silver insert. I believe this is slightly shorter going from the link to the tech doc at the beginning of this thread 11.2mm rather than 13.2mm. Although in the tech doc it does mention a 13.2 silver insert as well (YM-BH81) to me that just really confuses things but I'm going to ignore this. I think that make sense.

BG2000

I recently changed from a M775 setup to M985 (i.e. next generation up).

The olives are the same, but the inserts different (slightly shorter and silver). The hose nuts are also shorter, and the rubber sleeves go right over the nut onto the brake lever body.

The older type I used with XT M775:

---

Newer type for M985:


I'm fairly sure, like previous generations, there's no difference between XT and XTR bits, so I suspect the newer parts above will fit your M785 levers.

BikeBen

Thanks BG2000.

clamps81

Hiya, trimmed mine today and 'twas a doddle. Unless you are fairly dextrous you need another set of hands or failing that, a vice. Fittings on mine were as the photo above. Remove hose, slide bolt and cover back, cut hose, slide new olive on, bang in new insert (we reamed the end of the hose with a tiny screwdriver first and used a rubber mallet to bang it in) and then shove it back in the lever and tighten the bolt. Took about 10 minutes to do both. Front needed bleeding anyway, so we did that as well, back was fine. Hope that's helpful., let me know if you need more info about anything.

BikeBen

Hey Clamps

Thanks for your report. I went to my LBS and they found for me in their workshop one of the yellow Shimano hose clamps and the bleed block to go in between the pistons which I didn't have which was cool so hopefully all set to do it this w/e. I'm just trying to foresee any problems before they happen. 2 questions:

1. When you remove the hose from the lever, there's no risk of leakage from the lever is is there?
2. Secondly to actually cut the hose I trust a sharp Stanley knife will do the job, or do I need proper MTB cable cutters?

That's all thanks!

matt@theforce

1, Unless you remove the resevoir cap or screw the oil will stay in the resevoir when removing the brake hose
2, I used a pair of Tin Snips to cut through the hose. What-ever you use make sure it's sharp to get the cleanest cut (I would imagine a stanley knife will be fine)

It really is as simple as Clamps say's to shorten the hoses 8)

Matthew

BikeBen

Thanks Matt. I know I should stop talking and asking about it and just get on and do it...

matt@theforce

Better to be safe than sorry, I was really nervous the 1st time I shortened a brake hose but having shortened a couple of shimano setups now I don't worry anymore.

You get a great feeling when you've accomplished something new.

Matthew

clamps81

As Matthew says, 'tis a doddle and no leakage from the lever when removing the hose. Not sure on a stanley knife for cutting though, as to get a clean cut you'd have to lay the thing on it's side or have a really sharp blade. Cable cutters were the order of the day when I did it because it's easier to get a nice square cut.

BikeBen

Hey Everyone

Just to wrap this thread up I just wanted to say that I shortened my hoses yesterday and to be fair it was pretty easy. It took about an hour as we took it easy and also pinged off one of the pad retaining pin r-clips across the garage and spent 20 minutes on all fours looking for it (needless to say we didn't find it until 2 hours later where it randomly appeared in the middle the floor).

To the people who early on in this thread suggested instead of waiting for the proper silver insert to just use a universal olive and cut the silver insert out of the end of the hose, I think that would be pretty much impossible without damaging the insert. I'm not saying it can't be done but it's not something that you'd want to do. For starters u need to get the old olive off which is squashed into place. We spent 5 mins carefully cutting this off with a hacksaw. Then cutting through the hose so that you don't damage the insert? Well we gave up but i might have another go sometime.

Lastly when shortening the hoses I took out the pads and pumped the lever maybe 4 times to move the pistons out. Then when the hose was shortened pushed the pistons back in place. The only thing I'm wondering if there is now either a higher pressure or relatively more oil in the system meaning you hardly have to depress the lever at all before it comes into contact with the pads. I assume I can either sort this out with the lever reach adjustment dial thing or maybe just release a bit of fluid out of the lever. I noticed when I re-attached the calipers to the frame and fork the pads seem to rub slightly, but to be fair i haven't re-aligned them or looked at it properly yet. Thoughts?

Thanks again for everyone's help!

chopchop

Apologies to resurrect this thread, makes more sense than to start my own though! Would this be the correct insert and olive to use on the m785 XT brake?

http://www.chainreactioncycles.com/Mode ... elID=69605

Dirtydog11

Yes!

chopchop

Dirtydog11 wrote:

Yes!

Thanks!