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Sierra rear caliper handbrake problem
birdii - 12/1/18 at 09:09 PM

Evening,

Ive been looking at a weak handbrake on my off side caliper. I have checked that the piston moves ok using the hydraulic circuit, no problems there and the foot brake passed OK on the brake rollers but when the handbrake is applied the piston doesn't move at all.

The lever on the caliper moves all the way to the travel limit when the handbrake is applied. It seems like something in the mechanism within the caliper is disconnected.

I got the pair of calipers as refurb items a few years ago and have only just got around to using them.

Any ideas of what might be wrong? I'm contemplating stripping it down for a look myself but i expect someone here will have been inside one before and have a good idea what the problem may be!

I was lucky to get through IVA with this, i think my tester was very kind to me, the only resistance on the rollers would have come from the LSD. I didnt see him test it but he said it was bad and i needed to look at it asap.

Cheers
Dan


mackei23b - 12/1/18 at 09:15 PM

In the first instance try winding the piston fully back in the caliper, then use the foot pedal to pump the piston back into place before trying the handbrake, only after you have a good foot pedal then use the handbrake and see what happens....

If the handbrake has been used prior to bleeding and extending the piston using the foot brake I believe that it can reduce the efficiency of the handbrake.

I hope this helps.

Cheers

Ian

[Edited on 12/1/18 by mackei23b]

[Edited on 12/1/18 by mackei23b]


Smoking Frog - 12/1/18 at 10:11 PM

As above. Got to be worth a try before stripping it. A angle grinder key may fit the piston to wind it back in.


birdii - 12/1/18 at 10:20 PM

I have had the piston in and out a few times but Iím not sure which order I re applied the brakes first so I will give it another try tomorrow as suggested, wind in, re assemble with pads then pump foot brake before trying the handbrake.
Fingers crossed!


chris - 12/1/18 at 10:44 PM

i had the same problem with mine i cant quite remember what i did but it was something like holding the handbrake lever on the caliper under tension whilst i wound the piston in and when i was ready to refit wound the piston back out whilst keeping the lever under tension the hanbrake inside the piston housing is connected to the piston by what looks like a .22 bullet which falls out of place if not kept under tension
well thats how i did it anyway


rusty nuts - 13/1/18 at 09:52 AM

Make sure you have plenty of slack in the handbrake cable, remove calliper , wind piston fully in then without pumping pedal or applyinerg handbrake wind the piston out manually to take up the clearance between discs and pads whilst replacing caliper after each adjustment to check,no need to secure. When most of the clearance is removed you can then remount it , pump the pedal a few times, make sure the disc isn't binding then finally adjust the handbrake . HTH, Mel


birdii - 14/1/18 at 08:15 PM

Thanks for the help, Locostbuilders community to the rescue again!

I think it was Mel's suggestion that actually did the trick, I tried winding the piston out then in, and then footpedal before handbrake but this didn't work.

The final attempt was to wind the piston out as far as possible while still being able to assemble the caliper, the handbrake instantly worked.

I thought I was going to need a new caliper so really chuffed with this result!

Cheers
Dan