SOHC.co.uk Forums > CB750

CB750F1 Rear Disc Brake

(1/5) > >>

Doswen:
The rear caliper piston won’t  retract leading to overheating.
I’ve been on this problem for a number of days now and can’t solve the problem - help please.
I’ve tried two different rebuilt callipers.
New HEL braided oil line with new banjos. The banjo bolts are shorter than the originals.
Tried two different seal kits in the master cylinder. Now had it apart 4 times.
The return hole is clear.
The only way the pistons will push back in is by undoing the bleed valve or the banjo at the master cylinder.
The brake works releases fine by hand but if it is run up and gets hot the brake binds badly and overheats.
To be honest I can’t see how the seals in the master cylinder release the pressure when they both face the same way and the cup on the end of the spring is over the outlet hole.
I don’t know what else to try.
I also rebuilt the front brakes (twin disc conversion) and have no problem with those.

Johnwebley:
After you have fitted a new caliper seal and bled the system..
Operate the pedal like you are  braking. The piston should move out. Then as you release the pedal  it should retract slightly.

Check it moves freely

Sent from my SM-A750FN using Tapatalk

Laverda Dave:
To add to John's comment, make sure the outside metal edge of the pad is clean with no rust as this can sometimes just cause enough friction between the pad and the inside face of the caliper body to prevent the pad from fully retracting.

Moorey:

Is it a F1 seal kit as they can be very hard to find now.

Doswen:

--- Quote from: Johnwebley on October 09, 2020, 11:20:24 AM ---After you have fitted a new caliper seal and bled the system..
Operate the pedal like you are  braking. The piston should move out. Then as you release the pedal  it should retract slightly.

Check it moves freely

John, the piston moves out and retracts enough to free the disc when the wheel is turned by hand.
If the braking is under load with the engine running it will get progressively hotter until is completely locks up.



--- End quote ---

Navigation

[0] Message Index

[#] Next page