Changing and bleeding M785 XT brakes

starbuck

I've just bought a full set of M785 brakes from rosebikes. When they turn up (hopefully in a few days), I know I'll have to swap the levers over (which seems easy enough).

Looking at the way my brake hose is secured to the frame, it goes through near-closed guides with only a small slit at the top. Because of this, I don't think I'll be able to fit the rear hose without draining the oil out, fitting it and then refillling/bleeding.

2 quick questions:
a: is there any way when I disconnect the lever from the hose, I'd be able to feed it through the guides without draining it (or is it too risky due to the possibility of spillage).

b: if I do have to drain, refill and bleed, any idea how much mineral oil I'd need to fill a rear brake? I've seen the shimano bleed kit and the yellow funnel thing. Would the bleed kit be enough? Would it be better to get 1ltr of mineral oil?

nicklouse

You will also need new olives do get a bleed kit as it should come with all th bit you need.

Read the manual first to chech I you need the filling cone or not.

Greer_

a) nope, I think you'll have to drain it unless you have a surefire way of creating a vacuum so air cant get in (or the fluid out) so i'd just drain it

b) Something like 240ml is enough for over 4 brakes, so you won't need a litre unless you're planning a lot of bleeding.

Have a look here for a bleed kit - http://www.ebay.co.uk/sch/i.html?_nkw=shimano+bleed+kit makes it much cheaper than the shimano bleed kits that don't give you enough of anything.

Epicbleedsolutions.com come really well recommended but their kits are cheaper on ebay!

starbuck

Thanks for the suggestion of the bleedkit.

If I'm just swapping the levers over (and draining the rear hose) would I need new olives? I thought I could use the existing ones as they're already in the hoses.

nicklouse

starbuck wrote:

Thanks for the suggestion of the bleedkit.

If I'm just swapping the levers over (and draining the rear hose) would I need new olives? I thought I could use the existing ones as they're already in the hoses.

Will they fit through these mounts you mention? I expect not.

Shackster

I think most people have to shorten the hoses anyway, as they are very long for most bikes. You can do this without having to bleed afterwards (although I did this and one went fine, but had to bleed the other) but you would then need new olives and inserts. They should come with the brakes.

If you do have to shorten the hoses, then I would have thought you could feed the hose up through the guides from below, with the bike raised on a stand, so that you keep the hose vertical - you might need to bleed afterwards but you won't need to drain them fully.