2 Brake Distribution Blocks (Proportioning Valves)

[tg11350]

I am working to restore a 1968 Ford F250 Camper Special. It has heavy duty drum brakes in the rear and disc brakes in front. As I am working on the brakes I notice that there is a distribution block (proportioning valve) on the drivers side frame rail, behind the steering gear about a foot. This is normal and usual. Both brake lines from the master cylinder go to this block with one outbound line going to the rear brakes and one line heading to the front. The line going to the front however travels to another block. This one is bolted to the front frame crossmember, which suggests it is factory. Two lines then come out of this block and goes to the right caliper while the other line travels to the left caliper. It does have a terminal on top that I figure must activate the brake light if it is out of balance. This truck is so old there was no wire connected to this block.

I've never seen this before and I've owned a lot of cars and trucks over the years. What is this? Is it factory? Is it needed? Wassup?
I'm more curious than concerned since the 2 blocks (valves) are different in appearance and function. The main block on the frame rail manages fluid and pressure to the front AND back, but the smaller block on the crossmember looks to be auxiliary and only handles fluid and pressure to the front; left and right. BTW this truck has power brakes.

I hope I have been clear as I've explained this.

Thanks,

Tony

[cash667]

Hi Tony,
this is factory for front disc and rear drum.
The block on the left framerail ist just a distribution block with the brake warning light switch in it. It distributes pressure from each master cylinder port to either rear and front and recognizes pressure differences in either line and turns the brake warning switch on.
the second block on the crossmember is a metering valve which delays the front calipers to the rear brake shoes because a drum brake needs a bit more time to get full contact and brake power.
The small Pin on it is used to bleed the front brake lines and calipers, it manually holds the valve open. When you don´t use that Pin you´ll have to apply full power to the brake pedal to force the metering valve to open.

well explained on the fordification tech articles:
https://www.fordification.com/tech/propvalve101.htm

Cheers
Chris

[sparky72]

cash667 nailed it

[tg11350]

Thank you cash667. Obviously I had no clue per my post. The brake article you point out added further explanation. And, I had no clue what the red light was on the lower left side of the dash. Now I do from reading tech article. I continue to learn more about my '68 F250 as I go along.

Thanks,
Tony