Tried bleeding my brakes, but can't get any pressure - the pistons barely move and the lever has no resistance.
Anyone give me any ideas? - I can't see a leek either.
Excessive lever travel is usually a sure sign of air in the system. Are you sure the bleed was good?
Also have you tried altering the free stroke adjuster?
How did you bleed it and what with?
Not 100% sure on the bleed - I used the top down method
Just feels like the system won't pressurise.
I'm going to try the bottom up method later and see if that improves things!
Are there any specific seals that tend to go, etc?
Would a poor bleed, mean the levers have no resistance at all?
Yes, you either have a leak, which you say you don't have, or still have a bunch of air in the system.
The lever hasn't somehow become disconnected from its piston plunger has it?
I started the driving me insane thread, struggled with them for hours. The pad travel wasn't a problem with me to be fair, but give the calipers a good tap with something plastic to dislodge any bubbles. Also found that pulling the lever and letting it spring back shook the reservoir and lever any dislodged any air trapped in there
Wind the free stroke screw out when you bleed them. This gives you a better bleed and makes the screw actually do something.
Cheers for the tips guys, will give it another go later and see how I get on!
Well, seems it was full of air! Bottom up certainly seems to of hav improved things a lot.
The one thing I'm not completely convinced about is the amount of travel before I get Before the brakes seem to stop. Is this purely to do with pressure and if so, how do I improve it - I've pr viously had hopes and avids, both of which gave almost instant bite after bleeding!
As mentioned in the other thread you need to bleed the brakes with the free stroke adjuster fully out, then wind it back in after bleeding.
And mentioned on this thread too 😉
Bottom up is always the best (except for those few brakes you can't do it with). Air wants to rise after all.
Yep - done with the free stroke adjuster wound out.
I had a similar problem too, messed about loads but finally cured it and got effective breaking back:
Loosen the caliper
Loosen at the handlebars
Loosen further at the caliper
Loosen further at the handlebars
Now this part is key.
Put them in the bin and laugh at them.
Now fit <new brakes> M785 which appear to be OK so far.
I faffed around for so long, I could get a good bleed but after a couple of rides all bite would disappear. I'm pretty sure they were leaking somewhere in the caliper but could never prove it.
Personally I find this method works best for me..
Put the funnel on the lever..
Fill a 100ml syringe with about 75ml of brake fluid and attach to the caliper with hose. I put a small cable tie over the hose to keep it tight on the nipple. Also remove the nipple cover.
Open the nipple 1/4 or so of a turn..
Now push fluid up to the lever with the syringe and fill the funnel, remove some of the fluid from the funnel with another syringe.
Tap the caliper and hose to loosen and trapped air..
Continue to push more oil up the to the funnel and fill it.
Now suck oil back down from the funnel into the syringe at the caliper..you should notice small air bubbles coming out..
Continue this until no air bubbles come out..topping up the funnel so that no air can enter at the lever.
Tighten the nipple and remove the syringe but leave the hose in place, attach a bag or pot to collect any oil that's about to come out of the hose in the next step.
Pull on the lever and hold it..at the same time open and close the bleed nipple quickly. Do this a couple of times..air bubbles may come and be visible in the hose. It important to keep the lever compressed while opening and closing the bleed nipple.
Release the lever after tightening the bleed nipple.
Reattach the syringe to the hose so that there is no air gap in the hose.. Open bleed nipple and suck oil back down..keeping the funnel topped up.
Do this till no air bubbles come out.
Then finally push oil back up into the funnel..and fill it up a few times for good measure.
Tighten bleed nipple.
With the funnel still attached and say half full of oil... Pull and release the lever hard numerous times..
Small air bubbles should come out into the funnel.
I do this with the lever horizontal and pointing up and down..just important to make sure that the oil covers the port in the lever so no air can get in..
Do this till no air bubbles cone out.
I agree it sounds long winded but my brakes are rock solid.
Sorry just noticed this is M775 not M785.
Same rules apply...just takes longer keeping the lever resevior topped up..or not overflowing. As you can't attach the funnel.
Another tip is to wind the free stroke screw out in the lever. Not all the way mind you.
Wind it back in is meant to make the reservoir smaller..