For those of you who havent followed any of this build so far, the truck has 4.5" over long travel beams in the front, chromoly axle shafts, a detroit truetrac and 4.88s, and now the rear has a shaved disc brake 14 bolt with a yukon grizzly, 4.88s, and a tone ring on the carrier for the speedo/tcu.
I ran into some weird brake problems with the truck last week. Not sure if the proportioning valve was screwed up or the rear abs block was freaking out because of the disc brakes in the back, but i was having a problem with the rear brakes dragging. And it got bad...
I ended up dropping the truck back off with jon and had the booster/master cylinder swapped out for a new f350 unit, he gutted the proportioning valve, deleted the rear abs unit, had the rotors turned, and installed new rear calipers and pads. I picked up the truck tonight and drove it home with awesome brakes.
I also put a timing light on the truck and advanced the ignition timing a few degrees since I had installed a MSD 6al box, MSD distributor, Ford Racing wires, and new spark plugs a few months ago. It really woke the truck up a lot!
Between the ignition parts/timing, headers and full 3" exhaust w high flow cats, and now the 4.88 gears the truck gets up and goes pretty good!