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My neighbour had an over the bars moment and since then have been having issues with the e4 rear brake. After the off the bars had spun and the brake hose was tight as it was wrapped around, the brake lever then needed to be pumped to get the brake to work as the lever pulled to the bars. Didnt think anything of it, next ride out the rear brake had basically stuck on.
Had a quick look today, I've had hope brakes for years and I am fairly good at centralising the caliper and getting the pads equal but can't seem to get this one playing ball. Finding the More I pull the lever the more the brake binds on.
I've pumped the pistons nearly out one at a time, cleaned and lubricated and they are not sticking. I did notice after that when pumping the lever with the pads out one piston is slower than the rest, but pushes back OK? Another thing I noticed it with the pads out I can push the pistons back in without much force. When the pads are fitted and I'm trying to equalise them the inboard pistons are very difficult to push back with the little screw driver behind thr pad trick, other side is no bother
I'm seeing two possible issue, either the hose is faulty after being twisted around so tightly and is damaged inside or the piston seals are not allowing the pistons to move back when the lever is released.
Has anyone else had this issue before?
Having seen kinked and damaged hoses let go (thankfully in the workshop, not on the trail), i'd be changing it regardless. Should narrow down the possible causes of problems too.
I've had them stick like that after serious use, I think the fluid behind the piston must boil. A bleed has sorted it
How about this for a theory, as usual accurate diagnosis is difficult without having the brake in front of me.
The hose has a kink in it, this will allow fluid down due to the pressure applied by the lever, the fluid will not be able to return to the master cylinder as the hose is too constricting, therefore, the calliper is constantly pressured?
I had my front binding on a while ago and it turned out my pads were too low. Changed them out and all solved.
How about this for a theory, as usual accurate diagnosis is difficult without having the brake in front of me.
The hose has a kink in it, this will allow fluid down due to the pressure applied by the lever, the fluid will not be able to return to the master cylinder as the hose is too constricting, therefore, the calliper is constantly pressured?
My money is on this.
Just because you can't see the hose kinked on the outside doesn't mean it isn't inside..
The hose has a kink in it, this will allow fluid down due to the pressure applied by the lever, the fluid will not be able to return to the master cylinder as the hose is too constricting, therefore, the caliper is constantly pressured?
+2
Replacing the hose would be a sensible starting point if it's been twisted around in a crash.
As above, kinked hose. I’ve had exactly this phenomenon in the past and it was a kinked hose.
Try swapping the callipers front to rear and vice versa. If the problem moves to the front, it's a calliper issue, if it stays rear highly likely to be kinked hose as mentioned above.