Brake master cylinder rebuilt, anyone?
 

Hey All,
I blasted and painted my pedal assembly last weekend and will be moving onto rebuilding my brake system. I'll be breaking out my sandblaster again for the calipers. I am debating whether I should rebuilt my master cylinder or just buy a new one. Has anyone rebuilded their early (up to -1977, non booster) master cylinder?, and do you have any tips as how to go about rebuilding one?. Thanks for yur help, y'all. Andy

I rebuilt many master cylinders and actually had some work afterwards. Not all that hard. But if this is for the ’71, I would consider buying new or professionally rebuilt and since you’re there why not just upgrade to a 21mm unit. I say this because the master on the preboast cars is the lowest point in the system. This used to be the saving grace for drum brake 356s. Moister and the resultant damage it can cause collects in the master. I guess “you got to ask your self are you felling lucky…” Or more correctly are you qualified to tell if the master is worn beyond reuse?

Do you guys know anything about rebuilding a 23mm boosted MC? I picked one up cheap for my brake conversion (looks very nice, but unknown history), and would rebuild it before installation, if it's possible.

Andy & Noah:

When disassembling, obviously note the exact sequence of how things come out. There is a set pin that comes from underneath the mastercylider that looks like a plain bolt head. Note where that set pin hits the internal components.

What you are looking for inside the cylinder is any indication of pitting or corrosion that would have been caused by moisture. If any exists, chuck it.

Re-assembly use a little sil glyd on the edge of the cups and orings, and lots of brake fluid while inserting the new pistons. I use very thin feeler guage stock wrapped around the piston seal to help it into the cylinder so nothing gets nicked.

Noah . . I have a 23 mm on the bench disassembled if you would like to take a peek.

Thanks Marc, David and Noah.
I'll try and open it up before I buy a new unit. Andy