Remember seeing a thread a while back about swapping hoses over on slx brakes from Germany. Have tried loads of different searches for it but have drawn a blank. Pretty sure it said to pump the pistons out then simply swap hoses and push pistons back again but wanted to check.
Can any one help?

That’s pretty much it. Pump pistons a few times, detach hose, insert new olive/connector using the yellow tool; squeeze piston with finger until bubble of fluid appears and reconnect.

Thanks for your reply. Am I looking for a bubble of fluid at the hose end before I reconnect?

found it
http://www.shimano.com/publish/content/global_cycle/en/us/index/tech_support/tech_tips.download.-Par50rparsys-0008-downloadFile.html/02)%20Brake%20Hose%20Trimming.pdf

and here:

http://singletrackworld.com/forum/topic/slx-brakes-2

H

“Making sure that the lever is higher than
the caliper, bleed the brakes by pushing
the pistons back into the caliper. If any air
entered the system when the line was cut it
will be forced into the reservoir. “

Bit worried about that, air in the reservoir is still a problem, no? Wouldn’t that require a full bleed?

Also, why must the yellow blocks and vise be used when reinstalling the connector? Can’t it be done handheld?

H

Bit worried about that, air in the reservoir is still a problem, no? Wouldn’t that require a full bleed?

Nope, that’s the point of a bleed, to force the air out of the lines and caliper where it is a problem and into the reservoir. True, you don’t want to leave the air in there for too long as it may re-enter the system if you turn the bike upside down, so best to take the resevoir cover off, top up the fluid and replace the cover (or as you’ve got the new style brakes – use that yellow funnel thingy on the bleed port for the same result).

I tried this last night with some XTs from Rose, and shortened the hoses at the same time, and, true to form for the first time I try any fettling task, made a bollix of it.

When I “pumped the pistons a few times” I had a load of fluid escape from the front piston, and now squeezing the front lever doesn’t make the pistons extend, so the brake is going to have to be topped up and bled, I think.

What is this yellow funnel tingy of which you speak, perthmtb? Don’t think I got one of them with the brakes. Is it part of a specific bleed kit?

You don’t need to pump the lever ‘a few times’. Once does fine and no chance of pistons popping out.

What is this yellow funnel tingy of which you speak, perthmtb? Don’t think I got one of them with the brakes. Is it part of a specific bleed kit?

On the older Shimano brakes – like M665, M775 when you did a bleed you had to remove the reservoir cover to let air out and top up the fluid. On the newer models – like M666, M785 there is a different (and simpler say Shimano) bleed process whereby you just unscrew a small port on the top of the reservoir and screw in a special yellow plastic funnel instead. See here for instructions on how to use it – bleed instructions

And no, it doesn’t come with the brakes, you have to buy it separately – its part number 10 in this – XT parts diagram

Here’s where I bought mine – Yellow funnel thingy

In case I’ve confused anyone, I should add that if you do the swapping lever process properly, like described in the links above, you shouldn’t need the funnel. That’s for use during a bleed, and the whole idea is to try and swap the hoses round without needing to do a bleed!

But, if you push the pistons too far out (like I did 😳 , and StefMcDef above) then that lets air in, and you do then need to do a proper bleed, and that’s where the yellow funnel comes into play on the newer models of brakes.

^ Thanks for all that info, Perthmtb.

Anyone know if it’s possible to bodge a bleed on the new-style Shimano XT brakes or is this funnel contraption a crucial part of the process?

Also, is Special Shimano Oil absolutely necessary or will generic brake oil work just as well?

Great service from Rose but whatever savings I thought I’d make by buying the brakes from Germany are unravelling at a rate of knots. 😥

Look at eBay for shimano brake bleed kits. Cheap as, but no funnel. You will still be able to bleed it the normal way, out of the caliper with them.

Can anyone tell me, when you ‘pump the pistons out’ at the beginning of the hose swap process, can you just use the yellow caliper bleed block to ensure the pistons come out but not too much? Or will that not let them out enough?

H

Anyone know if it’s possible to bodge a bleed on the new-style Shimano XT brakes or is this funnel contraption a crucial part of the process?

The funnel is just supposed to make things easier, but a ‘normal’ bleed by removing the reservoir cover is still perfectly doable on the new brakes. Here’s the Shimano instructions for doing a bleed without the funnel – Bleed

Also, is Special Shimano Oil absolutely necessary or will generic brake oil work just as well?

Shimano brakes use mineral oil. Other makes like Avid, and car/motorbike brakes use Dot fluid. Don’t put Dot fluid in your shimano brakes, but other mineral oils should be Ok. Any LBS should have a gallon of the stuff around, and may be willing to sell you some if you bring your own container 🙂

Can anyone tell me, when you ‘pump the pistons out’ at the beginning of the hose swap process, can you just use the yellow caliper bleed block to ensure the pistons come out but not too much? Or will that not let them out enough?

The yellow bleed block doesn’t let the pistons come out at all. If you want them to come out a ‘bit’ but not so far that it breaks the seal and lets air in, use something about half the thickness of the yellow bleed block – I use a plastic tyre lever. Still, be careful, one piston could still come out all the way while the other doesn’t move at all, so keep an eye on them as you pump.

How about using the rotors as a stop? Thanks for the info btw.

Shimano orange brake fluid and Magura Blue Blood are definitely thinner than LHM, be it Citroen or Halfords.

You can use it, but I think it is too thick to work properly at low temperatures in a cycle brake system. I have it in some old Julies and a Deore, but I will not use it in my newer XTR and XT dual-control packages.

Your choice, obviously.

PaulD

Also, with the hose(s) off the levers, is it worth it to push the pistons back in a tiny way before refitting, to coax the fluid back up to the connecting end, thus making the chances of air in the reservoir lower and reducing the need to bleed them again for a while…?

How about using the rotors as a stop?

Not a good idea! Without the pads in (and you do want to remove the pads before you do any of this – saves them getting contaminated by oil!) by the time the pistons get far enough out to hit the rotor, you’ll have popped both the seals. Anyway, have you thought about how you’d push them back in again 😉

Also, with the hose(s) off the levers, is it worth it to push the pistons back in a tiny way before refitting, to coax the fluid back up to the connecting end, thus making the chances of air in the reservoir lower and reducing the need to bleed them again for a while

Sounds good in theory, but I have a feeling in practice you’ll end up pi$$ing brake fluid out the end of the hose 😆

Ok man, I’ll just use a tyre lever and stop worrying about leaving a bit of air in the reservoir. It’s just that I’ll be doing this to brand new brakes and my OCD makes me want them to be PERFECT!!!!

How do you format quoting what other people say?

Ok man, I’ll just use a tyre lever and stop worrying about leaving a bit of air in the reservoir

Don’t let me put you off trying it – sounds like others have had success squeezing a small bead of oil out, and that’d certainly make it less likely any air will enter into the system – I just know I’m so hamfisted I’d be squirting it everywhere 😀

How do you format quoting what other people say

I highlight then copy what I want to quote, then click on the “quote” tab once, paste the text, then click on the “quote” tab again…

Ta, bit of a forum noob.

Epic bleed kit on eBay for about 7 quid, comes with two syringes, genuine oil and explicit instructions. I used one when doing my m666 hoses. Piece of the proverbial and doesn’t risk popping pistons.

doesn’t risk popping pistons.

How? Don’t you still need to pump pistons out for the hose swap?

No, you swap the hoses then inject fluid into the system via the bleed nipple, thus purging any air. It really is that simple. All this talk of pushing pistons out troubles me because it can avoided by buying a kit you’re going to need anyway. The bleed kit has a syringe to attach to the gland on the reservoir so it’s all pretty fuss free.

That sounds better to me. I’ve got to do this job on my M666 after buying euro brakes and last time I bought one of those cheapo bleed kits for old BR486s it was fine.

I guess, without the funnel, you have to take the reservoir cap off entirely and watch for bubbles coming out, top up then whack the cap back on?

On the M666 you only need to remove the circular cap off the gland. That’s the one on the left in this image,

sexy, ta.