Stuck rear brake caliper

spasypaddy

Hi

I have an ultegra rear brake caliper thats stuck. When i pull the lever it locks up and doesnt release. Ive released the tension on the cable and it still doesnt spring back.

what can i do?

thanks

Bobbinogs

If you have disconnected the cable completely and the caliper still doesn't sprint back then I would start with trying to move it back manually to see if I could work out why the spring tension was insufficient to overcome any resistance (which should be minimal). If the caliper isn't moving then I would say it is likely to be one of those two factors (resistance or spring tension) at fault. If the resistance is too great when moving manually then remove the caliper from the frame (to avoid contamination when completing the next step) and then apply a generous amount of light oil (like 3in1) to the pivot points after removing the pads/blocks. Leave overnight and then see if it has freed up a bit. A loss of tension in the spring is a bit trickier but it could be that the spring clip has detached from the little holder (be careful mucking around with this bit because if you do unattach the spring then it could flip out and take a chunk of flesh with it...he says from painful experience!).

keef66

The cable's no longer attached to the caliper and it's still sticking? Take the caliper off the bike and strip it down. Look on Shimano Tech Docs for an exploded view of the relevant model which should help. Either the pivots are gunked up with dirt and / or corrosion, have been over tightened, or the spring's bust / dislodged.

Give everything a good clean and lube and it should be good to go again.

If corrosion has really set in, and it's not uncommon in rear calipers ridden through the winter with no mudguards, then simply replacing it may be the easier option depending on the depth of your pockets.

dj58

Remove the caliper from the frame, take out the brake pads and soak all the pivot joints with Plusgas releasing fluid and manipulate the arms to see if you can get it to operate correctly.

dee4life2005

^^ I have to the above every couple of months with my ultegra brake callipers ... the pivots get clogged with all the crap that gets thrown at the calliper when riding in wet weather and eventually it'll make the calliper sticky. I wouldn't ride with it like that too long, as I did and had to write off a wheel shortly after as it had worn away the brake track.

It took me about an hour to get both callipers operating again doing as DJ58 mentioned above - just be careful that you dont push the arms too close together though as I did that and the spring popped out the wee black plastic bushing and was a right sod to get back in (had them pretty much touching to do that though).

spasypaddy

cheers everyone

plusgas it is !

Monty Dog

I've dismantled and rebuilt quite a few brake calipers in my time - not something you want to do in a hurry as it involves tiny Allen keys and grub screws. If dunking the calipers in a bucket and going at it with a toothbrush which working the pivot points doesn't help then it may require disassembly if there's corrosion in the pivots. You'll also need some Loctite to re-set the grub screws on reassembly.

spasypaddy

might just buy a new one if plusgas doesnt work

frisbee

A security torx driver makes unhooking and hooking the spring incredibly easy. The hole is pretty much the perfect size from the spring.

spasypaddy

i covered it in wet lube and now it moves freely.

thanks for the help!