seized brake cylinder

[chilly]

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....

In my original post I said it was 'seized' not sized. I actually say it twice.

I've disconnected the cable Since you suggested that an incorrectly adjusted cable might be the cause (even though I knew it wasn't).

I have given the facts.

it moves the 2mm VERY RELUCTANTLY (probably more like 1.5mm)

[bmcecosse]

I dunno why you bothered coming on for advice - when you know so much about it! Good luck.

[chilly]

I dunno why you bothered coming on for advice - when you know so much about it! Good luck.

Thank you bmcecosse.

I actually wish I hadn't bothered now

[horologiumwatches]

Ha ha ha, classic stuff. Don't worry Chilly, bmcecosse is always right, "it's never the coil!"

[chilly]

Oh, I never thought to check the coil! Do you think that might be why the piston has seized in my brake cylinder?

[kennatt]

BM is correct..... it's impossible to get the hydraulic piston to move out of the cylinder without first removing the handbrake linkage and pin.,the lever prevents it. There are two pistons in the rear brakes,and the one that usually sticks is the outer one, if you can see a flat end it's... the outer one, .the inner has a slot where the handbrake lever sits.and its not possible to turn the outer to free it unless lever etc. are removed because the lever prevents it

[kennatt]

no response Eh not on your naughty step now roy by any chance

[bmcecosse]

Indeed he is.... pity really - I try to help when I can.

[chilly]

BM is correct..... it's impossible to get the hydraulic piston to move out of the cylinder without first removing the handbrake linkage and pin.,the lever prevents it.

I know

There are two pistons in the rear brakes,and the one that usually sticks is the outer one,

I know there is. The outer (handbrake) piston HAS stuck INSIDE the cylinder . (like I've said on numerous occasions)

if you can see a flat end it's... the outer one,

I CAN see a flat end because it IS the outer one. And it's STILL stuck inside the cylinder (but it doesn't matter now cos the whole SEIZED cylinder is sat on my bench now and a nice shiny new one is on the car )

the inner has a slot where the handbrake lever sits.and its not possible to turn the outer to free it unless lever etc. are removed because the lever prevents it

I didn't mention trying to turn it!
With only 2mm of the [outer] piston protruding out of the cylinder there isn't enough to get hold of so trying to turn it to try and free it wasn't an option anyway. Did I mention only 2mm protruded? (I'm sure I did somewhere).

--------------------------------------

Naughty step? I'm gutted .........

[whyperion]

I have a number of rears on the bench , with handbrake levers disconnected , I assume I fill a nice grease gun with brake fluid and apply a few times with luck the piston parts should pop out. Clean up, check for any leakage or excess wear then reassemble as required.

As said only a small movement on the piston (as the unit itself also moves in the backplate) should be needed to apply a properly adjusted brake shoe arrangement.

[kennatt]

just give the a good soak with plus gas etc(Not wd40) put it in a vice and gently tap the piston back into the cylinder ,then push it back out via the lever slot etc etc it will free up,once out enough to get hold of the piston turn it,then clean it up. the inner usually,is ok,leave it in,if you pressurize the cylinder you may push the whole lot out (Unless you want to ) and risk damaging the seal.If its not leaking leave it in,
One thing extra, depending on the age of the back plate,(ive had a couple like this) have a close look at the tabs on the brake slot,they can get flattened and although the cylinders fits and ,looks ok , it can let the cylinder tilt when you brake,and it throws the adjustment out, just gently re align the tabs.(This on ser11 don,t know if same design on later models)

[MarkyB]

The grease gun method is what people use on disc callipers particularly on motor bikes so they can be cleaned and the seals replaced as long as the bores aren't scored.

As the chances of the bore in a sticking Minor rear cylinder being in good enough condition are minimal and given the low price of replacement trying to refurbish one seems like a waste of time.

[chilly]

As the chances of the bore in a sticking Minor rear cylinder being in good enough condition are minimal and given the low price of replacement trying to refurbish one seems like a waste of time.

The conclusion I came to.

[liammonty]

I have a number of rears on the bench , with handbrake levers disconnected , I assume I fill a nice grease gun with brake fluid and apply a few times with luck the piston parts should pop out. Clean up, check for any leakage or excess wear then reassemble as required.

As said only a small movement on the piston (as the unit itself also moves in the backplate) should be needed to apply a properly adjusted brake shoe arrangement.

I think that regardless of whether a 'small movement on the piston' is sufficient (which I don't totally agree with, as the movement needs to be far greater than on disk brakes, for example), the point is that the pistons should be able to move freely throughout the entire range that they are supposed to - anything less is a bodge, and if you are going to bodge stuff, best to do it to something other than the brakes As such, the OP's decision to replace the cylinder is smart - I suspect that without re-sleeving the old cylinder, it would likely be scrap.

[dalebrignall]

just get a new one