Girling brake master cylinder

[davidj]

Hi,

I have just removed my brake master cylinder, (earlier single circuit design, chrome cap). The circlip and boot have been removed and the piston moves easily in the housing against the spring. The problem is the piston does not "pop out" of the housing. When pressed, it returns to its original position with a metallic clonk. Is there a pin stopping the piston from springing out, or has a step been worn in the bore which is catching the piston?

Thanks in advance for any help.

David

[davidj]

Hi,

I should have added I have removed the master cylinder to replace the seals! The manuals pearl of wisdom is "pull the piston and valve assembly from the cylinder". As the piston is still within the cylinder, there is nothing to pull it out with!

Cheers,

David

[ppnelan]

The piston should slide out, but as you say there could be step in the bore where the piston seal never reaches. Try 'tapping' it on something to 'shock' the piston out - it is steel & might have enough momentum to break free?
Or use air pressure - block the pipe hole & use an Eazibleed or bicycle pump or similar?

Matthew

[paddy]

It is possible that there is a small burr on the cylinder bore (outside of the circlip groove) where the circlip has been continuously knocking against it. It's worth carefully deburring it with a very fine file or something (don't go beyond the circlip groove) - otherwise if you force the piston out you could end up scoring it.

Paddy

[neilsjuke]

You can pop them out with a air line down the outlet but I would not mess about get a new one .