Sticky brake problem

liamo

Hi guys,

I've been trying for the last number of evenings to free up my sticky rear brake (Shimano Tiagra).

Following a very mucky spin and my failure to clean it for a couple of days (mea culpa) my rear brake won't release fully on its own.

I've removed and cleaned it with water, degreaser and WD40 and lubed it well with no success. It will release most of the way but that's it. I can manually open it the rest of the way and have spent plenty of time with the above mentioned chemicals closing and opening the mechanism trying to free it - no luck. It's not unusable but it's rubbing slightly against the rim and the brake lever has a lot of play.

To preempt the question, no it's not the cable that's sticking.

If I absolutely have to dismantle it and clean it, I will. But before I run the risk of ending up with a lot of loose brake parts that I can't re-assemble, I'm hoping someone will have an "Aha! Have you tried ..." suggestion.

Any and all suggestions welcomed.

Regards,

Liam

Lumen

liamo wrote: »

Any and all suggestions welcomed.

Right then. Bathe it in diesel for 24 hours. And don't blame me if you subsequently crash 'cos there's diesel on your brake pads.

CheGuedara

Lumen wrote: »

Right then. Bathe it in diesel for 24 hours. And don't blame me if you subsequently crash 'cos there's diesel on your brake pads.

Best remove them brake block first perhaps...

victorcarrera

Is it possible that the caliper expander lever was accidentally or otherwise flicked up? This would also cause the symptoms you describe.

liamo

Lumen wrote: »

Right then. Bathe it in diesel for 24 hours. And don't blame me if you subsequently crash 'cos there's diesel on your brake pads.

Thanks, I'll try that. (And I won't blame you)

CheGuedara wrote: »

Best remove them brake block first perhaps...

Yes, that would be a good start.

victorcarrera wrote: »

Is it possible that the caliper expander lever was accidentally or otherwise flicked up? This would also cause the symptoms you describe.

I'm not familiar with the term "caliper expander lever". Are you referring to the quick-release lever? If so, no it's not that. But thanks for the suggestion.

tomvamos

There is a small alan bolt on the face of the calliper to the right hand side. Try and loosen this off a little. I know you said it's not the cable but if possible try fitting a new one to make sure this is not your problem as this is the most common cause of callipers sticking. Tom

liamo

tomvamos wrote: »

There is a small alan bolt on the face of the calliper to the right hand side. Try and loosen this off a little. I know you said it's not the cable but if possible try fitting a new one to make sure this is not your problem as this is the most common cause of callipers sticking. Tom

I'll try loosening that tonight, thanks.
It's definitely not the cable as the mechanism is still sticking after removing the cable. The cable itself has been cleaned and lubed.

DirkVoodoo

Could be you might need to dismantle it and have a look at the left/right pivots.

Pain in the behind but at least your brakes will get a nice overhaul and you will be riding a safer machine.

Instructions, if you need them, here.

Also, the "small allen nut" is just for minor adjustment of the center position and I don't think its part of the problem here.

liamo

DirkVoodoo wrote: »

Could be you might need to dismantle it and have a look at the left/right pivots.

That's what I'm hoping to avoid. If Lumen's diesel suggestion doesn't work, I reckon I'm going to have to go down that road.
Thanks for the URL.