Airpak - to rebuild or not to rebuild

[Indyj100]

Hi all,

I began working on the brake system of my M211, the master cylinder was completely dry.
I filled the system and bled it to the best of my ability but only got a stiff pedal and no brakes.
Eventually with the stiff pedal I forced it the whole way to the floor and heard a clunk and the brakes started working although with a very spongey pedal.
My assumption is the piston in the airpak was stuck and broke free, does this sound right?

Now going with that assumption I removed it thinking it'd be pretty corroded inside but instead it looked fairly pristine aside from some gel like gunk on the spring side of the piston.
The seals feel fine and the main piston held my weight when I plugged the air holes. I know these specific vehicles had work done on them in the 90s and it kind of looks like it may have been rebuilt at some point.
Does it make sense to reinstall everything and try again now that it seems to be freed up? Is rebuilding worth the hassle?

The only thing I'd really want to replace at the moment is the piston itself as it is a bit marked up, but then again does it matter? The gasket seems to be the only sealing surface so does a rough piston wall matter?


Also, I snapped one of the 90 degree air hose fittings. Does anyone know what type it is off the top their head? If I get an answer from here it gives me less time at the hardware store and more time to remove the broken end from the air hose, that should be fun. Picture below shows which one I'm talking about.

(edges are a bit blurry and sorry for the workspace, it's our old batting cage)

all help is appreciated, thanks!

 

[Indyj100]

Forgot to ask the main question in the original post, is the situation I described some form of telltale issue that warrants a rebuild?
If my logic is right I'm thinking I can just throw this back together and it should work but if this is a sign of an issue then I'll rebuild.

Again, thanks for any help

 

[tommys2patrick]

i am no expert but give your post some time. my two cents is that these are designed to be rebuilt. rebuild kits are available. hardware store fittings may not be appropriate on these. i would take the fitting/pieces to a truck brake shop see if they can sell you the proper fittings. might even be someone on SS that can sell some to you. perhaps one of our vendors.

 

[tinygpw4]

1/2 penneth..if you have trouble getting rebuild parts..re sleeve and replace with a similar truck kit which is also possible.
(carried out at a refurb historic brake and clutch centre).