proportion valve for drum/ drum

[easyrider]

I'm having trouble getting my brakes to work right. I put power brakes on truck and I think my proportion valve is not working correctly. I can't find anyone that offers this valve for 4 wheel drum set up. Can anyone tell me where this can be purchased? Or, can I repair this one? And, can you run this without this valve???
Thanks.....

[pjmoreland]

GMCPauls sells the drum/drum distribution block.

https://gmcpauls.com/Brakes.htm

Part number 3349966

[LockDoc]

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As PJ mentioned above, you need to look for a "distribution block", not a proportioning valve.

LockDoc

[BigBird05]

only disc brake trucks use a proportioning valve. Drum brake trucks do not.

[easyrider]

Thanks guys for clearing that up..Now, at least I know what I'm suppose to be looking for....

[jocko]

On a drum/drum system, you "can" run without a distribution block since the mc provides the general biasing and you will have two separate circuits for safety, however, it's not advisable as you would have no indication (other than "feel" - which may not be so obvious) that you've lost one circuit and are operating on a single circuit - at which point you are back in '66 operating on a single circuit master cylinder (but with only front or rear brakes in this case) and generally no way to know it. The distrib block provides the pressure differential-sensing shuttle valve that triggers the brake light on the dash.