gear jammer 91"

My truck has had a clunk going from on throttle to off throttle for a long time and I think it's in the rear axle, so I'm trying to fix it before it brakes.
I'm getting ready to pull my rear diff cover off for the first time and would like to know what to check for as far as wear items. I know the cross pin can come loose, but I don't know how to check it or how to stop it from coming loose. What else wears out back there?

jogl

Are you sure that it is not just the axle rolling and the springs, hangers, etc making the noise?

JP.

wannadiesel

The cross pin gets worn, it doesn't fall out. You have an open diff? If you get the cover off and find a limited slip the trouble is worn clutches, but if they have gone too long the spiders and side gears are shot too.

There should be no appreciable slack between the pinion and the ring gear. You don't mention howling so I would bet the ring&pinion are fine. Slack between the diff case and axles is what you are looking for, that will be caused by a worn cross pin in an open diff or worn clutches in a limited slip.

gear jammer 91"

Thanks wanna, that's the info I am looking for. As far as I know it's not a posi, I haven't found a tag on the diff that say's it is, but I'll be finding out for sure soon.

jogl, I'm pretty sure it's not axle wrap. I've had those issue's in other trucks, this issue feels completely different. Also, the back end doesn't hop when I do a burn out. . . even dropping the clutch in third gear in the burnout box at the track.

Dave F

What I do to to check drive train slack is have a competent person in the drivers seat with the engine running. Watch the drivelines. Clutch disengaged, select 1st, gently drag the clutch. Select reverse, drag the clutch repeat till you have found any excessive clearances. Then, engine off, ebrake on, forcefully twist the drive lines by hand.

gear jammer 91"

I can rule out the rear axle as the source of my slop. Everything was tight, no posi, at least I couldn't see any clutches. With the rear tires of the truck off the ground and the trannie in gear I can turn the drive shaft about a 1/2". This seams like to much play to me. My transmission has been rebuilt at some point in time, but the transfer case looks untouched, I don't know if wear in the transfer case could lead to that kind of slop or if my issue is in the transmission.
I am pretty sure it's not worn out mounts. With my hand on the shifter I can't feel any movement from side to side or up and down when going from off throttle to on throttle.

77machomopar

I wouldn't mind only have a 1/2 inch of play. i can turn my drive shaft 3/4 of a turn. it makes the same noise yours does.

92roughstock

1/2" of play sounds like spipder gear slack to me.

On your carrier (inside the diff), did the side opposite the ring gear slope off, more rounded, or was it squared, like a cylinder? If the latter, it's a limited slip. You wont see the clutches.

gear jammer 91"

The half inch of play I got was with the back of the truck on jack stands with the trans in gear, I turned the drive line by hand and saw about a half inch of play looking at the back of the transfer case. With the rear tires on the ground and the trans in neutral there is almost no play in the drive shaft.
The carrier was rounded on the side opposite the ring gear.
I've got a buddy with a tranny shop, I think I'm gonna let him look at it and see what he thinks.

gear jammer 91"

I drove our 93 at work today. It has 100k less miles than mine, a 4 month old rebuilt D70 and, a two year old rebuilt getrag. With all those new and lower millage parts it still has the same kind of clunk when going from on throttle to no throttle quickly. I'm starting to think nothing is wrong with my truck, it's just a diesel thing. Who knew it wouldn't drive like a 2wd 96 S-10.