tweaking proportioning valve

[averagef250]

Disc brake Proportioning valves seam to be like a magical component that nobody's allowed to fiddle with. Anybody fiddle with them? I regularly swap disc brake front axles under highboys and search out the entire braking system from a 76-77 F-250 4x4 lines, hoses, prop valve, brackets, everything to make the install look factory. I've done several trucks with a 60 front and 70 rear. The 60 front discs work great, but the big 70 rear drums tend to lock up way to soon. I would like to keep the 76-77 proportioning valve and lines because they fit so nicely into the older chassis, so anybody know if I can modify the prop. valve to change the braking bias?

[ladz]

We installed a wilwood disc break proportioning valve in the rear break line after the stock valve , in the frame rail and it works great part #260-8419 www.wilwood.com

[72hiboy4x4]

so you are the one making it hard to find the parts to do my truck up!

[averagef250]

It is my goal to buy up all the hard to find old Ford 4x4 parts in the NW just to piss you off! Actually, while I have had many hard to find axles, trannies and parts pass through my shop, I've also bought alot of parts rigs just for one part that I had to have and darn near gave the rest of the truck away on craigslist to get it out of my driveway. I hate to think about all the old Ford trucks I've killed for the good of a handful or so.

I've used the adjustable valves as well as the load-sensing proportioning valves Ford used on many of thier 1 ton trucks in the 80's and early 90's. I'm really trying to figure out a way to change the bias of the valve itself. I've taken the valves apart, cleaned them and reassembled them, but never really taken the time to figure out what makes them tick inside you know? I would like to find a way to enlarge a hole a little bit or put a shim under a spring to actually tune the brake bias to where I want it.