What is the best way to bleed Shimano hydraulics?

alivio · Jun 2, 2010

I have non series shimono brakes and I wanted to know if there is any "unofficial" way to bleed them. My pads are not new but not really worn out either, I have tried bleeding them even though I don´t have air in the system, the front brake goes into the handlebar and when they were new they started biting alot further out, they should be self adjusting but thats just crazy talk.

The problem now is I have to overfill to get them to bite, and if I overfill the bike gets unrideable due to massive rotor rub, are these brakes just bad brakes?

jeffscott · Jun 2, 2010

Take the wheel off.

Take the pads out.

push the pistons all the way in.

level and remove the lever cap.

fill a syringe with a tube with fluid, get ALL the bubbles out.

put the tube over the bleed nut, open bleed nut, push fluid up through the system.

Wipe or suck excess from lever reservior.

Push more fluid in....(you can suck the excess from the reservoir and return it to the bleed nut if you have the patience).

Do up bleed nut....install lever cap.

clean and dray caliper and lever with IPA. blow with air...

Insert pads, put wheel on...

Rebed the pads...

AL29er · Jun 2, 2010

From the horses mouth.

Personally I bleed them like a car, top to bottom. Never had any issue with that method, been doing it for about 6 years. Also, no special tools or syringes required.

CommuterBoy · Jun 2, 2010

I have always had Hayes, but I have found that the reservoir isn't big enough to bleed them from top to bottom... if you fill it, cap it, and then squeeze the lever...you are already sucking air into the system. Maybe Shimanos have a bigger reservoir? Bottom up is quick and easy with the right tools though... I made a syringe out of one of those snot-sucking bulbs for babies, and a piece of clear tubing.

forkboy · Jun 2, 2010

AL29er said:
From the horses mouth.

Personally I bleed them like a car, top to bottom. Never had any issue with that method, been doing it for about 6 years. Also, no special tools or syringes required.

Egggzactly.

The only issue I've run into is getting all the tiny air bubbles out of the MC itself. It can be a very time consuming process the first time if you have totally dry factory new levers.

wormvine · Jun 2, 2010

I bled my shimano brakes about 4 times trying to tighten up lever feel and for other issues.
I tried Bikeradar.com's method which is to use a light vacuum at the caliper and just let gravity and suction pull fluid from top to bottom. You can read about that method in Bike radar's workshop section.

Shimano user literature suggests the traditional car bleed process which is to open the fluid reservoir, and pump and hold brake and then open bleed valve (with catch tube and container) for just till the brake moves through its throw. Repeat this process many times while making sure you do not let the reservoir get too low to suck air back into system. It's easy to do.

I figured out a better way though. Everything is the same as the traditional way but I only open the bleed valve a little bit (small wrench stays on valve) and then I continually pump the lever slowly and I am filling the reservoir the whole time as it drains. Because the bleed valve is only open slightly there is some resistance at the lever but I can still force fluid out the valve much faster than the traditional way. Just make sure you always shut the bleed valve before you release the lever on the last pump. And keep the reservoir full or you will be starting all over again.

Frankly I think the Hayes 9's are the easiest the bleed with the right tools but shimano has the least upfront cost. It would be nice if they included about 12" of tubing with their brake kits. Maybe they include it with a bottle of fluid but I use Pentosin CHF 7.1 mineral oil.

PissedOffCil · Jun 2, 2010

I bled my GFs XTR in the past weeks (rear, then front this weekend) and all I did was :
1) Plug the tube on the calipers bleed screw with bag attached
2) Unscrew lever top cap (after flipping levers so it rests on top)
3) Open bleed port
4) Let oil flow down, refilling reservoir as it empties
5) Once the oil start getting his color back (old oil was pale), close the bleed port
6) Test for feel
7) Repeat if necessary
8) Close resevoir
9) Collect the pay!

So far, the easiest brake to bleed I've ever worked on. If only they had bigger mineral oil bottles than the 50ml that comes with the kit...

forkboy · Jun 2, 2010

wormvine said:
It would be nice if they included about 12" of tubing with their brake kits. Maybe they include it with a bottle of fluid but I use Pentosin CHF 7.1 mineral oil.

They come with the levers. You get bottles of fluid, a couple pieces of tubing and some fluid catch-bags.

wormvine · Jun 2, 2010

forkboy said:
They come with the levers. You get bottles of fluid, a couple pieces of tubing and some fluid catch-bags.

Good to know... I received my XT's as an OEM kit and they did not come with the tubing.

As a side note for all, A 20oz plastic coke bottle is a great catch container. Just drill a hole in the cap big enough for the tubing to slip tightly through and a smaller hole in the cap for pressure release. Wrap a piece of metal hanger around the neck and make a hook to attack to bike to hold is securely.

in the trees · Jun 3, 2010

wormvine said:
As a side note for all, A 20oz plastic coke bottle is a great catch container. Just drill a hole in the cap big enough for the tubing to slip tightly through and a smaller hole in the cap for pressure release. Wrap a piece of metal hanger around the neck and make a hook to attack to bike to hold is securely.

That's exactly what I did as well!:thumbsup:

What is the best way to bleed Shimano hydraulics?

alivio

jeffscott

AL29er

CommuterBoy

forkboy

wormvine

PissedOffCil

forkboy

wormvine

in the trees

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