68 brake question

[68 c20 cst]

I was taking my truck apart for a long bed to short bed conversion and found this proportioning valve. Haven't seen one like this. Would this set up be good for disk drum? I have drum drum now.
Thanks

[LockDoc]

-
Not sure what that is but I don't think it is a proportioning valve. A proportioning valve has to be connected to front and rear brakes and is only used with disk/drum setups..... Drum/drum brake systems use a distribution block.

LockDoc

[camtoys1]

thats adjustable proportioning valve.

[LockDoc]

Originally Posted by camtoys1

thats adjustable proportioning valve.

It isn't going to do what it is supposed to just hooked up to the front brakes.

LockDoc

[RichardJ]

>>It isn't going to do what it is supposed to just hooked up to the front brakes.<<

Wrong. I am guessing and assuming it is connected to the rear brake line only, which is correct.

[68 c20 cst]

Yes it's just on rear brake line. So would this setup work for disk/drum? Or would I still have to change booster/MC/PV?

[Grumpy old man]

Thats a 64-73 Ford Mustang adjustable prop valve

https://www.mustangbrakeparts.com/pr....asp?prod=9422

old school trick for trailering or cheap mans option for line lock .

Call pirate jacks for all your brake questions http://piratejack.net/

[LockDoc]

Originally Posted by RichardJ

Wrong. I am guessing and assuming it is connected to the rear brake line only, which is correct.

So what is it supposed to do on a drum/drum brake system, only connected to the front or rear? (other than what Grumpy suggested)

LockDoc

[67 chevelle]

Get one of these

http://www.ebay.com/itm/GM-CHEVY-DIS...FXdMFO&vxp=mtr

That way you will have a warning light , and the proper valve

[RichardJ]

>>So what is it supposed to do on a drum/drum brake system, <<

I'm guessing again, but I imagine the guy was having a problem with the rear brakes locking up. Assuming all the drums were working as they should, I think you are looking at a very aggressive driver with poor brake habits that frequently drive in adverse conditions.

Any truck with no load will have a lot of weight transfer, rear-to-front when braking. That truck has a heavy Big Block and big ass brake booster. You add that to someone that drives too fast in the rain, tailgates and jumps on the brakes at the last minute and that truck might be prone to swapping ends.

Below is an adjustable proportioning valve used on some trucks before ABS brakes became common place. When the bed rises, the arm connected to the axle, adjusts the proportion valve to reduce the pressure to the rear brakes. With a load in the bed, the valve doesn't reduce rear pressure. There is less rear-to-front transfer, the tires are loaded and the wheels don't lock up.

Yes, a Combination Valve would add a warning light switch and also add a Metering Valve for the front brakes.
When you add disc brakes, the truck may have a tendency to nose dive at very low speeds with light brake pressure then a Metering Valve would be very useful. In other words, if you plant your girlfriends face in the dash at red lights, either add a free standing Metering Valve or replace the adjustable prop valve with a Combination valve that has a fixed proportion valve and you should be good and ready for the disc/ drum set up.

The adjustable valve is better than a fixed valve, but probably not needed.

[LockDoc]

Originally Posted by RichardJ

>>So what is it supposed to do on a drum/drum brake system, <<

I'm guessing again, but I imagine the guy was having a problem with the rear brakes locking up. Assuming all the drums were working as they should, I think you are looking at a very aggressive driver with poor brake habits that frequently drive in adverse conditions.

Any truck with no load will have a lot of weight transfer, rear-to-front when braking. That truck has a heavy Big Block and big ass brake booster. You add that to someone that drives too fast in the rain, tailgates and jumps on the brakes at the last minute and that truck might be prone to swapping ends.

Below is an adjustable proportioning valve used on some trucks before ABS brakes became common place. When the bed rises, the arm connected to the axle, adjusts the proportion valve to reduce the pressure to the rear brakes. With a load in the bed, the valve doesn't reduce rear pressure. There is less rear-to-front transfer, the tires are loaded and the wheels don't lock up.

Yes, a Combination Valve would add a warning light switch and also add a Metering Valve for the front brakes.
When you add disc brakes, the truck may have a tendency to nose dive at very low speeds with light brake pressure then a Metering Valve would be very useful. In other words, if you plant your girlfriends face in the dash at red lights, either add a free standing Metering Valve or replace the adjustable prop valve with a Combination valve that has a fixed proportion valve and you should be good and ready for the disc/ drum set up.

The adjustable valve is better than a fixed valve, but probably not needed.

Yeah, it's hard telling what he was up to.

To the OP: When you do the disk swap I would just put the correct combo valve on it and set it up correctly, like Richard said....

LockDoc

[68 c20 cst]

Thanks to everyone for your help