10 replies to this topic

[J6collins]

Hello all,
I have a 1977 mini MkII that I purchased today. Everything in the car is great except for the brakes. The previous owner bleed the brake lines and could not figure out why the brakes would not work. I figured the master cylinder needed a bench bleed. I pulled it out of the mini (huge pain in the butt getting the pin out) and decided I wanted to rebuild it.  I am having trouble getting some sort of guide to disassemble the cylinder. I have taken the c clip out and now have a cap that I assume needs to come off to get the inners out. If anyone has any advise or knowledge on the subject it would be much appreciated. 

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[panky]

The piston should come out once the circlip has been removed. probably stuck with a ring of rust and crud on the edge or the bore. Try pushing it back in and clean the inner edge up then give it a whack onto a lump of wood, end down to dislodge it. They can be quite stubborn, I've wrapped them in a rag before now and given the cylinder a shot of the air line through the brake pipe hole - be careful with that though.

[J6collins]

Way to make me feel like an idiot. Thank it came out after a few hits. 

[panky]

An idiot doesn't ask

[slidehammer]

I think if it were me I would go for a brand new master cylinder, I rebuilt one and it worked fine for about 6 - 9 months then the rear brake seals failed and I had no rear brakes (car is split front to rear) So for all the hassle of pulling the old one out I would just replace it. That is speaking as someone who has done loads over the years, but I feel the rubber seals aren't as good as they use to be. It is a matter of safety.

[Twincam]

I just rebuilt my clutch master cylinder, after pulling the circlip out I used compressed air through the screw hole and the piston inside flew out (as others have said)...

**be careful** put some sort of cushioning under it otherwise it could become a projectile.

When you rebuild, line the inner bore with some brake fluid and add some brake fluid to the seals to let them slide in freely.

Edited by Twincam, 20 December 2016 - 11:09 PM.

[J6collins]

Thanks, everyone for the help.

[Orange-Phantom]

Red rubber grease will be your friend when rebuilding your brake master cylinder. 

 

http://www.redrubber...ebuild-kit.html

 

http://www.demon-twe...d-rubber-grease

[J6collins]

Thanks

[J6collins]

End state is this was a huge fail. The inside of the cylinder was rusted out and it had to be replace with the GMC 227

[J6collins]

Does anyone know if the GMC227 front and rear hookups are reversed compared to the original