seized brake cylinder

[chilly]

Has anybody got any tips for freeing a seized rear brake cylinder? It's seized in the 'in' position. It does move in and out about 2mm from flush but that's as far as it goes. Cheers.

[MarkyB]

I've heard you can use a grease gun to pressure the piston out.
Much better to replace it though, going cheap on brakes is a false economy.

[chilly]

It's still connected up on the car but the hydraulics won't force it out.

[bmcecosse]

Is this a rear cylinder?? If so - the handbrake cylinder holds it in...

[chilly]

Yes it is the cylinder on the rear brake.
The piston isn't being pushed out of its cylinder by hydraulics when applying the brakes.
I don't know what you mean by the handbrake cylinder?

[bmcecosse]

It is working fine - but the handbrake cylinder is in the way. To adjust the brakes - slacken off the cables and THEN adjust up the brakes on the clicker. Only then, readjust the cables to put the handbrake lever where you want it...

[chilly]

It's not working fine as the piston cannot be pushed out of the cylinder!
Either when the foot brake is applied or when the hand brake is applied.
The rear brake DOESN'T work on this side of the car.

[bmcecosse]

You say it comes out 2mm.....that's all it needs to do. Adjust the brake properly... Your handbrake cable is too tight...follow the adjusting instructions above...

[chilly]

I'm sorry but 2mm piston movement is NOT enough to apply the brakes!

The handbrake has worked fine in it's present state of adjustment up until the brake cylinder 'SEIZED'

[liammonty]

I've managed to free off front cylinders in the past, with an able-bodied assistant heaving on the brake pedal while I eased the piston, rotating it slightly and easing it in and out. I think due to the additional bits for the handbrake etc. that that won't be possible on the rear, so the best course would just be to buy a new cylinder and be done with it. For what it's worth, the pattern REAR cylinders (not front!) seem to be OK. and are a fair bit cheaper than the genuine ones.

[chilly]

I've managed to free off front cylinders in the past, with an able-bodied assistant heaving on the brake pedal while I eased the piston, rotating it slightly and easing it in and out. I think due to the additional bits for the handbrake etc. that that won't be possible on the rear, so the best course would just be to buy a new cylinder and be done with it. For what it's worth, the pattern REAR cylinders (not front!) seem to be OK. and are a fair bit cheaper than the genuine ones.

Thanks. I have decided to just fit a new one.

[les]

Good idea, never worth messing about with old ones.

[amgrave]

Hang on a minute, the hand brake part of the cylinder is completely independent of the foot brake. If the hand brake has stopped working on that drum the outer piston has seized and it is quite alright to clean this part up without disturbing the hydraulic part of the cylinder saving a lot of work and fitting a new cylinder. If this is the case clean the outer cylinder up and replace with plenty of rubber grease, job done

[chilly]

Hang on a minute, the hand brake part of the cylinder is completely independent of the foot brake. If the hand brake has stopped working on that drum the outer piston has seized and it is quite alright to clean this part up without disturbing the hydraulic part of the cylinder saving a lot of work and fitting a new cylinder. If this is the case clean the outer cylinder up and replace with plenty of rubber grease, job done

The hand brake is fine! It's the hydraulic piston that has seized in the cylinder.

[amgrave]

Sorry about my last post but you said above "that the hand brake worked in it's present state UNTIL the brake cylinder seized".

[bmcecosse]

No - it hasn't -you are not understanding how the brake works.. But carry on - ignore the advice - new cylinders don't cost that much. Just seems a waste to do all that work when it's not necessary. The handbrake cylinder is simply stopping the hydraulic cylinder from moving more than 2mm because you have the CABLE tightened up too much

[chilly]

The handbrake cylinder is simply stopping the hydraulic cylinder from moving more than 2mm because you have the CABLE tightened up too much

Er, no I don't! The hand brake cable is not even connected!!

[IslipMinor]

The drawing below shows the construction of the front and rear brake cylinders:
[frame][/frame]
It is worth removing the shoes and seeing if the top part of the cylinder can be removed (Piston and Dust Cover).

Next check if the handbrake lever moves freely.

If it does then very, very carefully press the brake pedal, whilst someone watches to see if the 'piston hydraulic' part of the cylinder moves. If it does then that is not likely to be the problem.

Can you post some pictures of what you find?

[chilly]

Thanks Richard.
I've got the shoes off, hand brake disconnected and dust cover off. The hydraulic piston moves from being flush with the cylinder to protruding 2mm when you press as hard as you can on the brake pedal.
It's seized. As I said in my original post.

[bmcecosse]

You actually said is was 'sized'... And you didn't explain the cable was disconnected.... Hard to diagnose when you don't give us the facts. The pin for the handbrake lever is stopping it... If it moves 2mm it's not seized... But carry on - new cylinder! May as well do both sides....