Rear master cylinder strip LMII

Has anyone any top tips for removing the retaining ring on the master cylinder piston? Ive bought Brake Master Cylinder PS15 Brembo Rear Rebuild Kit. The intructions seem to show a circlip beneath the rubber seal but its actually a metal ring that must be an interference fit.

My question is does anyone have tips for removing this? When the piston is pushed in you get a better view but not sure how to get the thing out!

All tips gratefully received!

I seem to remember driving the whole lot out with a needle punch of 2mm diameter, through that little hole in the far end. When the new stuff goes in you need a extra long socket, something like 17mm, can’t remember exactly, I have used an old gudgeon pin, to use as a drift, from the other end. Whatever you use it must be a close fit in the cylinder to sort-of distort the washer-type thing and make it grip. Someone will probably come along soon with a better idea but that’s how I have done it in the past.

As mentioned above, drive the old piston out from the banjo end. A few sharp taps with a hammer will soon knock it out. I use an old blunt nail, it is not as if you are going to damage anything as you will be fitting a new piston any way. As for refitting the new ring, I have read a short length of 15mm copper pipe will do the job nicely, just push it home and it seems to click into place. Sure I pushed mine back with a screwdriver but a bit of tube or a long socket would be better.

The refitting of the linked master cyclinder piston etc requires a long thin walled socket .line up all the seals etc and tap the socket with a sharp smack with a hammer, metric hammer of course.one master cyclinder requires a 14mm socket and the other requires a 13mm but I cant remebemer which size fits where. the above is for a 1978 850T3 which should be the same as your bike.when removing the piston etc do not use anything with a pointed end as this might stick in the piston, use something with a smooth edge like a cut down Allan key. Thursday amJust had a look at a old linked brake master cyclinder and its the 14mm thin walled socket you require.





northwest2014-05-15 09:08:48

Thanks for all the advice, Ill give it a go, the next time I escape the house, thats under seize by 2 boys under 2!!

A 14mm slim wall socket and a 'leccy screwdiver with the tip cut off.

^ As above, think I used a bit of steel rod from B&Q. Need something firm like a vice to support the body while you hammer. To put new one in think I used steel tubing, but not sure.

I think i put this link up before…

http://www.laverdaforum.com/gallery/albums/userpics/11278/Repair_Guide_Clutch_and_Brake_Master.pdf

Fab, thanks all! Got the metric hammer, the long stand, a tub of elbow grease, spare bubbles for the master cylinder and a bag of sparks for the grinder! Now slightly annoyed that this weekend away is going to put me into next week before I get near it! Excuses excuses! -HJB-2014-05-15 21:59:39

Do you need a new bubble for your spirit level? Will have to be a round one though ~ I did have a square one but I dropped it and knocked all the corners off