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Evening folks, I’ve never been a fan of bleeding brakes...
I’ve managed to bleed the front one without a problem and now it feels great. So I decided to do the rear but I just can’t figure out where I’m going wrong.
I’m using the Epic Bleed Kit instructions and have pushed the brake fluid through from the caliper to the lever and then let fluid drain through from the lever and out of the caliper (into hose and plastic bag). I’ve then closed the bleed port and then pulled the leaver to the bars whilst quickly opening and closing the bleed port a few times. I then close the bleed port and pull the lever to the bars again. At this point with the front brake the lever was very stiff but the with the rear it’s still pulling to the bars very easily.
Now I’m not sure if it’s worth pointing out but prior to bleeding the rear the bite point was very inconsistent and I’d often have to pull the lever twice to get a decent bite. Not sure if there’s another issue here? I thought a bleed might fix it?
Help!
Try bleeding it again with the bike suspended so the brake is much higher than the bleed port on the brake end (frame almost vertical), sounds like there is a trapped air bubble in the system. Also flick the cable hard as you push the new fluid through, this helps displace trapped bubbles.
As above, plus, I find it can help to "shove" the fluid through from the caliper. Give it short sharp presses rather than pushing it through gently. This can help dislodge air bubbles rather than just pushing fluid past them. If you need to, gently pull the fluid back into the syringe and push the same fluid through again. Keep going to no more air bubbles come out the top. Tap the cables, tap the caliper, close the caliper bleed port and flick the lever - whatever it takes to dislodge the bubbles.
I've never bothered with letting fluid flow from the lever to the caliper. Just push it up from the caliper. When you think you're done, close the caliper bleed screw and check the lever feel. If it's good, put the bleed screw back in the lever, then open the caliper bleed port, gently push a little fluid in so that the reservoir is full, then close it off and you're done.
The inconsistent bite point is caused by having air in the reservoir. As the fluid sloshes around, sometimes the air will get into the hose, and sometimes it won't. It gets worse as the pads wear as there's less fluid in the reservoir.
Take the brake off the bike and hang it from a hook (lever at the top😁).
Run an electric toothbrush over the full assembly to vibrate any bubbles out of any nooks n crannies.
Top the lever up with few drops of fluid in the morning.
Job done.
I've had a mare recently with Shimano rears. I've even resorted to leaving the top cup on and open for a week to try and allow air to rise out.
The whole gravity bleed thing seems nonsense.. the fluid doesn't flow out fast enough to carry air with it. It's great for a fluid change but not for a bleed as far as my failures have suggested.
What I've found (as far as I can tell) is that I'm getting air stuck behind one of the pistons. The solution that's so far worked has been to have the bars as high as possible (caliper low) do a gravity bleed but with a couple of inches of clear hose attached to the bleed nipple. Whilst allowing gravity to push fluid down from the cup but having the caliper slightly higher than the 'bottom' of the system and taps the sh*t out of the caliper and let gravity push and the air rise.
If you get a small air bubble in the bleed hose, if you point the caliper
/Clear bleed hose down again you can watch the bubble rise back into the system even while the fluid is flowing out. So keep the bleed hose pointing up and get that last bit out.
This has been my solution after doing a number of normal push bleeds, push pull etc.
This works for me.
Another vote for Marshy's method, works a treat.
Same here. Works every time on both mtb and road hydraulics.