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Yes folks, you read that right.

I heard an alarming sound and I drove the truck straight home to check it out. I parked in front of the garage and opened the doors to pull in but the truck wouldn’t go any further.

After pushing it into the garage I found the drive shaft laying on the ground, with the u-joint in tact attached the whatever you call the part it attaches to-the part the drives the rear end.

See pic. I couldn’t find the part in my service manual.

Of course I want to know what would cause it to fall off? Maybe a couple of thousand miles driving with a vibrating, crooked and out of balance drive shaft? (Which had been fixed a while back) But that part isn’t bolted on in any way? !!

What is that part called? And how do I fix this? How it it supposed to be attached to the rear end?
1967 D100 drive shaft with u-joint still bolted on to the rear-end drive thingy

—Jeff

67D100Pickup wrote: ↑

Sat Jun 03, 2023 6:49 am

1967 D100 drive shaft with u-joint still bolted on to the rear-end drive thingy

The yoke is on you.

Sorry, but it had to be said. You will need to supply the year, model, and type of rear end, to determine the number of splines. In case the axle had been swapped out, one is best off to count the number of splines. Once those factors are determined, a driveline shop can get you the parts if need be. In the mean time, do stuff a clean rag into the end of the differential around the pinion to keep dirt from getting in there.

The yoke fell off because there is a big @#% nut that holds it onto the pinion shaft and that nut loosened and fell off. It doesn't look damaged in the pic and you likely might be able to just put it back on, after acquiring a new "pinion nut" and washer if it had one. You will need to start by removing the UJ clamp bolts and removing the UJ. The nut is behind the UJ. They usually require a 1-5/16" socket and several hundred # torque.
Reassembly of the driveline requires a specific method for correct timing of the UJ's.

When you placed the transmission in Park (I assume the truck is an automatic) outside your garage, I am surprised that it remained stationary & didn't try to roll away since it had no drive shaft.

Does the pinion (the part inside the hole on the front of the rear differential housing) appear to be damaged? What about the splines inside of that yoke?

Bucky

PwrWgnDrvr wrote: ↑

Sat Jun 03, 2023 12:07 pm

The yoke fell off because there is a big @#% nut that holds it onto the pinion shaft and that nut loosened and fell off. It doesn't look damaged in the pic and you likely might be able to just put it back on, after acquiring a new "pinion nut" and washer if it had one. You will need to start by removing the UJ clamp bolts and removing the UJ. The nut is behind the UJ. They usually require a 1-5/16" socket and several hundred # torque.
Reassembly of the driveline requires a specific method for correct timing of the UJ's.

It looks like luck was on my side. The nut that holds it together was still sitting behind the ujoint and nothing looks torn up.

—Jeff

712edf wrote: ↑

Sat Jun 03, 2023 12:52 pm

When you placed the transmission in Park (I assume the truck is an automatic) outside your garage, I am surprised that it remained stationary & didn't try to roll away since it had no drive shaft.

Does the pinion (the part inside the hole on the front of the rear differential housing) appear to be damaged? What about the splines inside of that yoke?

Bucky

It’s a manual tranny but I came to a stop on flat ground. I don’t see any damage so I’ll just bolt it back together and hope I do a better job torquing the nut than the “professional” did that rebuilt the rear end.

— Jeff

make sure it spins freely
very possable the pinion bearing is bad
when you tighten it ,it might be chunky ....

nutz wrote: ↑

Sat Jun 03, 2023 10:04 pm

make sure it spins freely
very possable the pinion bearing is bad
when you tighten it ,it might be chunky ....

I would expect that at least the front pinion bearing should be changed out. It should be inspected. The whole point of all that torque the pinion nut requires is to compress a shim stack properly such that the bearings have the correct alignment and clearances and the gear engages the ring gear on the differential correctly. When the pinion loosens, all sorts of stupid stuff can happen in there, including damage to the gears. The degree of the problem depends upon how long it had been run loose and how it was loaded. The seal is probably toast. I'd suggest a very close look at the yoke to see if the mating seal surface has been damaged. New yokes can be hard to come by.

Now that I know the rear axle had recent work done on it, if I were D100Pickup, I'd take it back to the shop that rebuilt it.

Wildergarten wrote: ↑

Sun Jun 04, 2023 7:28 am

nutz wrote: ↑

Sat Jun 03, 2023 10:04 pm

make sure it spins freely
very possable the pinion bearing is bad
when you tighten it ,it might be chunky ....

I would expect that at least the front pinion bearing should be changed out. It should be inspected. The whole point of all that torque the pinion nut requires is to compress a shim stack properly such that the bearings have the correct alignment and clearances and the gear engages the ring gear on the differential correctly. When the pinion loosens, all sorts of stupid stuff can happen in there, including damage to the gears. The degree of the problem depends upon how long it had been run loose and how it was loaded. The seal is probably toast. I'd suggest a very close look at the yoke to see if the mating seal surface has been damaged. New yokes can be hard to come by.

Now that I know the rear axle had recent work done on it, if I were D100Pickup, I'd take it back to the shop that rebuilt it.

Thanks for this detail Mark. Working on it now…

67D100Pickup wrote: ↑

Mon Jun 05, 2023 6:31 am

Thanks for this detail Mark. Working on it now…

You are quite welcome. Sorry I was a little flippant with my first reply, but it was just too good a pun to pass up, "pathetic license" being a developmental disability.

Wildergarten wrote: ↑

Mon Jun 05, 2023 9:47 am

67D100Pickup wrote: ↑

Mon Jun 05, 2023 6:31 am

Thanks for this detail Mark. Working on it now…

You are quite welcome. Sorry I was a little flippant with my first reply, but it was just too good a pun to pass up, "pathetic license" being a developmental disability.

No harm, no foul. I’d like to think of an appropriate way to turn the joke around onto the guy that rebuilt the rear end. I don’t know about y’all but I think it is a serious offense if a professional doesn’t torque the damn nut and it falls apart. He needs to know.

Maybe explain how I was going down the highway when I heard it start falling apart, then ___ and ___ and ___, and thank goodness we’re still alive.

All ideas are welcome! ;-)

—Jeff