Ok so I did the conversion, and three years later my rear calipers keep locking up. Who did you get a disc/disc proportioning valve from and has anyone else had issues down the road?

 

The "combination valve" used on these trucks metered (held off) the front brakes so the rear drums could apply first. The other part of the valve is a differential isolate if one end or the other springs a leak giving you a warning light. If it was working before: check linings for contamination, check calipers for sticking, check the front side of the combination valve for proper metering. Assuming you bypassed the ABS hydraulic valve, the above would be your most likely candidates. If your ABS hydraulic valve is still in the system, it could be the problem.

 

The abs valve took a shot and I went around it. Should I change to a disc disc valve from jegs or something? My left rear caliper is hanging up, the same thing happens last time. The back right got changed the exact same time six months ago. The right is just fine! Is the proportioning valve not allowing as much movement out of the rear calipers causing them to hang? I can tell the rears don't do very much.

 

There wasn't a "proportioning" valve in the original brake hydraulics, just the combination valve and rear ABS unit. If you have one, it was added. If only one caliper is acting up, it could be from contaminated brake pads (usually from an axle seal leak), a burned caliper that binds, and or contaminated (as in burned) brake fluid. If you have an ebrake set up on the rear, make sure it releases freely.

 

What do you mean by burned fluid? When the caliper hang it gets the fluid very hot? I got everything together and bled, I think, and I have fade like no other. You get on the pedal, it's stiff, for a light slow down. When you get on it hard, the pedal just moves past the light slowdown, but doesn't really applying much more.

 

Burned fluid becomes black at beat, and sticky at worst gumming up a piston. During the bleeding process, it is easy to shift the isolation valve into cutting off 1 end. Check and re-center it.