I pulled this proportioning valve and all of the required disc stuff (spindles, UCAs, caliper adapters, etc..)out of a junked A body about 10 years ago. Gonna need it for my '71 Dart when I do the swap from factory 10" drums to disc.

Do these get gummed up internally over time? Any reason to break it open and see what's in there? Rebuildable? Or just bolt it in and go?

Are rebuild kits available?

Try here
https://www.musclecarresearch.com/1970-76-mopar-combo-valve-autopsy

I just purchased parts to rebuild mine, but have not done it yet.

There was a thread on here years ago in the Resto section that was pretty detailed with pictures. I don't have a link though.

Thanks! Just what I needed.

I'm not sure that is a proportioning valve, just a distribution block with a pressure imbalance switch for your "brake" light.

I took mine apart and cleaned everything, got some new O-rings and all is good.

Joe

It is one.

The section on the right in the picture is the proportioning valve. The section on the left is the pressure switch.

Great information,I Thank You too.

I hope the o-rings you purchased are made from EPDM rubber. The o-rings found at your local auto parts stores are typically made from a compound like Viton or Nitrile (Buna-N) rubber that isn't compatible with brake fluid. They will deteriorate rapidly.

I stand corrected, I see the hex head on the end now.

I did use a rebuild kit specific for my set-up with the proper
parts.

Thanks, Joe

Ditto