Beae with me, this may be a little long. I have a 1987 f-150 that I've recently bought. When I first start the truck, put it in first and leave, it goes a few inches then stops like a brake is hung up. I have to give it more gas to get past the hang up, then about 20 feet later I get a relatively loud clunk from the left rear. A friend and I pulled both tires and rebuilt the drum brakes (only small parts, not the drum or shoes) for both sides and it didn't do much. I have found out that if I dont engage the emergency brake when I park it and I just put it in gear instead, then I dont get hung up in the beginning, but I still get the clunk noise. Please give me any ideas you might have, thanks a lot guys.

 

Driveshaft loose in the rear end?

 

Well, if it changes when you do or dont use the ebrake, didn't you pretty much just answer your own question?

 

That would seem so, but if not I've seen that if the pinion nut is loose the pinion gear will jam in the ring gear and not let the vehicle move. If that is happening the vehicle would not move and inch, if brakes get hung up I don't think it would be as abrupt.

 

Sounds like 2 problems - your e brake cable is sticking and you have something loose in your rear diff.

 

I had the same problem on my 94. As it turned out my pinion nut was loose. I will say though, if that is the problem, don't drive this, as it will only make this worse. I made this big mistake, and the gears hit my posi traction housing, and destroyed the rear end all together.

 

Check all the u joints in the drive shaft. And if you have a longbed check the center carrier bearing and the bushing for it. If seen some that let the drive shaft flex so much that it caused it to bind at times.

If everything is ok on the driveshaft then put the back axle up on some jackstands and take the entire driveshaft out. If it's 2 pieces with a slip joint DO NOT separate the pieces.

Once the shaft is out. push in the emergency brake and make sure that neither back wheel turns. Then release the emergency brake and see if either wheel turns. Then also grab the pinion flange on the diff and see if you can move it up and down or side to side, there should not be any play.

Post back up with what you find out.

 

I had the exact same problem with mine; as long as I didn't engage the park brake I was ok. Turns out my 2.73 rear was on it's last leg. It started whining shortly and then was puking large amounts of gear oil. I replaced it with a 3.55 and am actually happy that I did, because take offs from a dead stop are so much better and my highway mileage didn't suffer any...