The Stovebolt Site Forums The Shop Area The HiPo Shop Disk/Drum Brake Proportioning valve needed?

I have a 51 chev shortbed with fatman mustang II IFS installed on the front and a 1974 camaro rear end with drum brakes.

I am just doing the brake lines now. will i need to install a proportioning valve for this setup to work, and if so, can i use a proportiong valve off of a 1983 suburvan?

What do you all recommend?

You could get a nice adjustable one from a place like www.jegs.com. Much easier to get right. And, if you have a load in the bed, bias it a bit more to the rear to increase your stopping power.

Generally speaking, you want to use a valve from a vehicle with about the same weight distribution front to rear. Doesn't have to be the same weight, just the same percentage F-R. So a valve from a later pickup (assuming it is known to be in good condition) would be a good choice for an early pickup. This will likely be a combination valve, with residual valving and a brake light switch incorporated into it.

That said, the new adjustable prop' valves are pretty inexpensive and easy to adjust. If you use one, you need to add a 10lb residual valve inline to the rear drums. If your master cylinder is still under the floor put a 2lb residual valve inline to the front discs to prevent fluid from siphoning back to the master when parked on an upgrade.

Joe

PS you don't say whether you have upgraded to a dual-circuit master, which I highly recommend. If you have the old single-circuit master, you will have to use the adjustable prop'valve. jw

The above is good advice. My 37 has Camero front disc and rear drums. I used a distribution valve from a late 70's Chevrolet Malibu. It was the same weight as my truck and only had two lines in and two lines out. Some of them have two lines out for the front brakes and one for the rear. With one out for the front, it was easyer to run lines. I also had to add a adjustable valve to the rear line to keep from locking up the rear brakes so easy. I just keep doing panic stops in a parking lot and adjusting till it quit locking up. Then I backed it off just a bit. Its mostly trial and error to get it right. Do it in a safe area before hitting the streets.

What about your master cylinder? What do you plan to use. Are you going with power brakes, they will need a different master than manual brakes.

Talk to the brake people and read there catalogs, they have good information ( you don't have to buy from them ). Try Speedway Motors for the adjustable valve, it was cheapest I found. Joe

Thanks for all your imput. I will be using an under floor power brake and booster setup from eci. Just thought i could save some money by using a wrecking yard combination valve from the suburban.

i know brake systems are something not to mess around too much with so wanted to make sure.