master cylinder kit

[asp2764]

Purchased rebuild master cylinder kit that is rubber seals only. Do pistons dis-assemble to install, if so how do they tear down?

Thanks

[Jeff G 78]

With the MC out of the car, remove the bolt in the bottom of the casting.  It holds the piston in place.  If it doesn't come out, you might need to pop it out with compressed air.  Be very careful not to shoot the piston out.  The kit should have seals for the piston as well as for the ports.  Those might not need to be replaced.  If you see any corrosion in the bore when you remove the piston, the seals will get chewed up very quickly if they seal at all.  Use a dental pick to GENTLY remove and assemble the seals.  Be sure to take photos before you remove the seals so you get them back together the same way.

[Mark Maras]

 Pull the snap ring out of the end and drop that end onto a piece of wood several times. The seals and pistons should move toward the open end. Keep them in order as they come out. Take a close look at the bore & pistons. I normally clean them with a Scotch Brite pad & brake fluid. After cleaning, inspect the bore for pitting. If the bore looks good, reassemble the new & old parts in the proper order, reinstall the snap ring & you're good to go. Oh yeah, It's best to loosen the bleeder screw first. just to make sure that it will. I rebuilt a cyl. once & broke the bleeder screw off after reinstalling the cyl. in the car. Never again.

[Jeff G 78]

Thanks Mark.  I forgot to mention the snap ring.  I was going off memory from 6 years ago when I last rebuilt one.  

[Mark Maras]

You're welcome. I forgot about the bolt on the bottom. It has been a number of years since I did a Z cyl. Most recent one for me was an 81 RX7.