Driveline slack

[spencerdiesel]

Hey everyone, truck has 173k. Cruising down the road in any gear, if you let off the throttle (taking slack out) then just reapply it, there is a lot of excessive play and things "smack" back the other way, taking up slack on the forward side of things.

Also, if I'm spunky and engage the clutch a little to quick when upshifting, there is a "clang".

Best I can tell the clang sounds like it comes from the flywheel/clutch/tranny area.

This wasn't an overnight thing, it's been gradual and now I'm realizing

[matthewh]

Any chance its a worn u-joint? I've had acouple dodges with loose rear axles, where you engage drive, and there's a definite clunky, and never had them make noise on and off the throttle like that. Usually that's a u-joint or carrier bearing

[spencerdiesel]

There's a very good chance it's a u joint, thanks man.

[spencerdiesel]

Had the truck on a chassis lift for the first time (every other lift has been a drive on) and it seems 80% of the slack is in the rear end.........the driveshaft can rotate 3/16" when tranny is in neutral.

I know this is bad, but run me through the possible worn components.

[justin.loehlein]

If it's not a bad u-joint, you haven't touched anything on the rear-end, have you? Re-tightening/over-tightening the nut that holds the driveshaft yoke to the pinion gear could cause it to move further away from the ring gear and create excessive play. If you rule out the u-joints, might be worth popping open the diff cover and checking for play in the carrier. You can use a dial indicator to see if you have excessive backlash (sounds like you should). If you use a medium length prey bar and can move the carrier left to right, you need to replace the carrier bearings or maybe try just re-shimming the carrier. If the carrier is fine and you can move the pinion gear excessively still, it might be a bad set of bearings on it, or the crush sleeve was crushed too much if someone re-tightened it (it takes a lot of force to do this though, like hammering on it with an impact gun).

If the rear end checks out, check the axles?

[CumminsPower59]

Another thing to check is how much play is in the slip yoke/joint on the driveshaft.

My 91 currently has a fair amount of "slop" in the rear drive shaft slip joint, not only side to side, but up and down too. It needs to be replaced pretty badly. After I rebuild the rear diff, I will have new drive shafts made for the truck as the custom front shaft has some slop in it too, hopefully all the new stuff will take away a lot of the drive line slop in my 91. The shaft is 25 years old, so it's due for some attention.

[spencerdiesel]

Thanks gentlemen. I haven't messed with the rear any, but I wonder more and more how hard the truck was worked in its previous life.

[CumminsPower59]

My pile has had the ever living snot worked/beat out of it. The rear diff has horribly loose bearings, worn out spider gears and a chipped pinion tooth. I've beat on it pretty hard, but knock on wood, it's still going. Believe you me, that when I finally get my VW up and going again (deer strike), "The Pile" will be getting some much needed love. I have all new bearings and shims, a Spicer Power Loc overhaul kit with new clutches and spiders, and a very good used set of 3.07 gears. I did find a company that had some NOS 3.07's for the rear, but they were over $500 I've been putting it off for warmer weather (50+F), so I am gonna pull the whole axle out and have it in the garage so it'll be easier to work on and not be crunched up under the truck

[spencerdiesel]

Wish I had a backup ride haha.

If I'm rolling in first, I can REV the motor up and down a 100 rpm window without ground speed changing a bit.

[Richie O]

Better pop the rear cover and have a peek. I have roasted 3 of these 70's now. I had 2 that wore the cross pin out holding the spiders and chuncked the monkey. Both of those decided to let go at 45 miles per hour and stop the rear wheels dead right now. Pretty impressive wheel hop and sideways slide to a stop. My last rear ate the side bearings out of the carrier and blew a pile of teeth into the pig.

[spencerdiesel]

Richie how much do you gross

[Richie O]

Richie how much do you gross

Most time on 89 and 93 its empty, 92 up to 20,000 with a 5th wheel triaxle equipment trailer. I hauled a tractor and a roller compactor together once with the 93 and must have grossed 25,000.