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Recently bled my front M4 with no problems. However, descending Walna Scar on Friday and near the end the lever was almost at the bars. This was happening a couple of weeks ago and was the reason why we bled the brakes. Any idea how I can sort it or is it time to send to Hope for a service.
Cheers all,,
was there any air behind the pistons?
Are you sure there is still no air in the system? Cable tie the levers to the bar overnight and open the top cap in the morning - you might see a couple of small bubbles. This has happened to me after a full bleed, even though I was sure and double checked there were no bubbles going through the system.
Complete bleed thru replacing all the fluid? Were you dragging the brakes a lot? If the lever has now returned to normal it might have been overheating
Yeah did a complete bleed through. Could air be getting into it somewhere ?
I'm flummoxed.
is the lever feel now normal? If so it was overheating
If not it must be air - could be a failed master cylinder seal - easy to replace
Are you using the Hope bleed kit or doing it "manualy" I had a problem getting Deejay's V2's form doing just what you described. Use the kit to get the best results, you can purge a lot of fluid through before the last bubbles come out.
just call Hope. They are incredibly helpful over the phone. Just don't try emailing them
yep can take ages to get all them bubbles out and even if you are getting clean fluid through some dirt and bubbles can still be dislodged a way after its comming thru clean
I had a similar thing on my old Hope Mini. The lever felt solid after a bleed, but if i pulled the brake on, then 'pumped' the lever it would gradually work its way to the bars, let the lever out fully and it would feel solid again. Tried bleeding multiple times, each time convinced I'd cracked it, changed the seals in the caliper same problem.
Eventually gave in and took it to a shop to see if they could do anything and it turned out to be the seals in the lever piston. There was no visible signs of fluid leaking from the lever so I didn't think the problem lay there! A year and a half on and its still working fine now.
Exactly the same problem here as mike_check.
Nice solid lever, indicating that there is no air in the system, but the lever would gradually make it's way back to the bar. Basically instead of pushing fluid down to the caliper, it's seeping back up into the top reservoir. You won't necessarily see any external leaks.
I replaced the master cylinder piston seals and all was well.
Cheers guys. I'll bob them in the post to Hope. CBA with the hassle on such an important component.
Happened to me as well but it was the seal in eth resevoir had a wee split in it. 5 minute job then back to solid brakes.