I have a 96 RAM 3500 van, rear wheel drive only, rear ABS only. I had to stop quickly the other day, and since then the front brakes have been dragging, and I can smell them burning. New front calipers, wheel bearings, pads, front rubber brake lines, and a new master cylinder. The boost rod seems fine and the cylinder is returning in 8 - 10 seconds after you release the pedal. My ABS light has been on since I bought it seven months ago, but It doesn't concern me. The ABS light went off briefly when I stopped, but went on the next day. It has a smell like power steering fluid ever since I bought it.

 

Do the calipers move freely on the bracket?

You have already replaced everything that could be responsible....... time to look at the proportioning valve? (though I don't think that could act as a one-way valve......)

 

X2! The sliders need to be greased periodically to keep them from sticking. Was this done when the parts where replaced?

 

I have a 1995 Ram 2500, two wheel drive, rear only ABS with intermittent front brakes dragging. I've replaced all active components except the RWAL (rear ABS component). I also replace the rubber hoses. There is a check valve built into the proportioning valve that allows the front brake fluid to return to the reservoir, but as the pressure drops the fluid returns much slower allowing my rims to get hot.
I could use help also.

 

how bad are they dragging? To the point you can't turn the front tires by hand when jacked up?

 

When it happens I struggle to turn the front wheels with both hands.

 

Calipers move easy on the guide pins? New calipers? Or still the originals? Flush out the brake system?

 

I've replaced the vacuum booster, master cylinder, both calipers and pads, both flexible front brake lines, rear wheel cylinders and shoes and reconditioned the proportioning valve. I have NOT replace the RWAL. This problem is intermittent, when it occurs the indicator pin protrudes from the proportioning valve about 1/2 of its travel, not enough to turn on the ABS warning indicator.

 

Hhhhmmmm...... Just out of sheer cussedness, check the rear brake line. (steel line, front to back) Wonder if you have one that is preparing to fail..... although, I don't think that would cause the fronts to exhibit odd behavior like you describe...... stranger things have happened though....

How does the pedal feel? Is it spongy at all? Excessive travel?

 

The brakes bleed out ok, peddle is firm. The steel lines look good.
I plan to buy a flexible brake line with the connectors that will allow me bypass the rear ABS device (RWAL). to see if the intermittent condition changes. I hate to just buy a new ABS unit to test with. I've already bought a proportioning valve that didn't change anything.
any other trouble shooting tips?