Proportioning Valve ?

[Ironhorse]

Tried to use the search function but it said the word "proportioning" in proportioning valve query was to long.

My question is:
The proportioning valve on my '71 4x4 with factory disc brakes is leaking at the rear of the valve. All the connections seem tight. I have a '71 or '72 two wheel drive that had a working factory disc brake system before I sold the rear axle and gears. Proportioning valve is still mounted to the master cylinder, far as I know it is still good. Has differant casting numbers but appears physically to be the same. Anyone know for sure if it will interchange? Don't want to pull the one off my running 4x4 until I know that I have one to install on it. Any help is much appreciated.

[jamie72]

i would think it would interchange, i would take the 2wd one off and hold it up next to the other one and see if it all mounts up the same.
or go to an auto part website and look up both trucks and see if it gives you the same part number.
good luck
jamie

[JimKshortstep4x4]

Although a 2 wheel drive prop valve may work, I would suspect that the two are different. Prop valves are designed to distribute the brake fluid "force" to match the weights of the front and rear of a vehicle. A 4x4 weighs significantly more in the front than a 2wd so I think they are different.

If you find out otherwise, please let me know.

Jim

[Huck]

I believe the proportioning valves deliver different pressure based on the disc or drum setup or in the case of non disc---different pressure based on the front/rear due to the braking power required.
I believe the Prop valve on the 4x4 and 2x4 disc brake setups are identical as I have several and the items are the same. You can get different part numbers on them due to aftermarket swaps. Example, if you order a master cylinder from any parts store, you could get several designs yet all with the same part number. I know Mothertruckers sells new and good used Proportioning valves very reasonable.