Vacuum brakes & Proportion Valve Question

Mike Swentzel

Dec 4, 2017
I'm finally going to Vacuum brakes, and my question is do I need my Vacuum Ball bc I haven't had it on for years? Also I'm considering a new porportion valve as mine is original and never been replaced or ever leaked do you recommend me replacing it and if so should I buy oem or a repop? Any knowledge would be helpful. Thank you
Vacuum ball yes. That’s what holds vacuum for the HVAC system, the selector, changing flow locations, etc.

As for the prop valve, I’d say depends on where ya live. If your not in the Rust Belt ya may be ok. When I did mine I switched to the brass prop valve. Just for my piece of mind.

Just make sure if ya change it you get the correct one for your setup, disk/drum or disk/disk.
Curious, has not having the ball affected your HVAC?

Perhaps it’s there to hold vacuum in a boost scenario. Seem like I memba something like that.
If you live in a hilly or mountainous area, you need the ball. Here in AZ. we commonly run in boost for MILES up in the mountains. The ball provides vacuum for the HVAC and cruise control.
What ball are are we talking about? Is it still avail? I have the vac setup as well but no ball.
gnfanatic, this is the vacuum ball I was talking about. It's located underneath engine compartment by the driver's side tire.


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It holds vacuum for the hvac and cruise control and for boost for the vacuum brakes. I don't have a ball on yet but will when I finally convert to vacuum brakes