Did you get the 7500 or 8800 gvw calipers? I put 7500gvw calipers on mine and picked up pads for an 8800gvw by accident. The pads were way too thick and I couldn't get the caliper over the rotor with the piston all the way in. Perhaps you have 8800gvw calipers with 7500gvw pads?

 

I think the 8800 GVW calipers were dual piston. They won't bolt on.....

 

I used the 8800 GVW calipers with matching pads. The 8800 GVW calipers are single piston just like the 7500's, just a larger bore.

I did verify the problem isn't in the master/booster. With the master plugged off and the truck running the pedal is high and firm.

 

You have 2 or 4 wheel ABS on that?

 

You have to have some air trapped somewhere.

I know you said bleeder screws facing up, but aee they on TOP of the caliper? Above the brake line?

You could try opening all the bleeder screws until they all are dripping fluid, then close them all off and re bleed.

 

2 wheel ABS.

The bleeders are indeed at the top, I even un-bolted the calipers and bled them perfectly straight up and down, and I have let it sit and drip bleed.

It makes no sense to me. Truck running, it goes to the floor with little resistance. Turn the truck off and one or two pumps and it's rock solid, and it stays that way until the truck is running.

In my experience if there's air in the lines, you'll either have a low pedal with the vehicle off and it running, or they will at least pump up with the truck running if you have a solid pedal with it off.