Drive Shaft Fell Off

Having the semi-circular clamps come out of the differential’s yoke is probably the most common cause for this sort of thing. I actually had it happen on a Dodge pickup about 25 years ago. My wife refused to go anywhere in that truck after that. I got another u-joint, pressed it in with my bench vise, and put it back together on the street. I drove it for several more years.

I find it very surprising that the OP says the u-joint looks normal. I don’t know how the rear end of a driveshaft could fall out, spinning on the pavement, and not lose the two exposed caps with their needle bearings. Does the OP know what it’s supposed to look like?

No, I don’t know what normal is. I just don’t see anything broken. I got some pictures if I can figure out how to get them on here.

The driveshaft fell OUT of the differential? ??? Not sure what you mean. On my Ford truck at least the driveshaft doesn’t go inside the rear diff. The driveshaft ends in a U-shaped thing, where the U-joints go. The other side has a u-shaped thing & (connected to the rear of the drive shaft by the u-joint arrangement) is what goes into the differential.

I’m assuming your driveshaft u-joint broke at the rear side, and that’s what caused it to fall off and land on the road, b/c the driveshaft actually has two parts, and they fit together using those splines you mentioned. It is designed that way b/c the driveshaft has to chance length a small amount as the suspension parts move. One thing you could do is look at the parts carefully, see if you can figure how the two parts are aligned, based on stains on the metal etc. Otherwise you may have balancing problem to contend with if you put it back together aligned different than it was.

A friend of mine had this happen to him way out the boondocks, and he had to get some bailing wire and tie the driveshaft up off the ground, and limp back to civilization using the front wheel drive part of his 4x4 truck.

Front of the drive shaft:

Whole in differential where the shaft pulled out:

Rear end of drive shaft:

Huh. Splined front and back. I’ll be interested to hear what the folks have to say. How do you even get it in on both ends?

There’s nothing (well, maybe) wrong with the driveshaft. The pinion yoke is off off the differential.

If you’re very lucky all you need is a new pinion nut, pinion seal, pinion yoke, driveshaft inspection and repair/balance, and some gear oil. But since you’ve driven the car with the yoke loose before it separated you’ve likely thrown the pinion bearing preload all to heck and will soon be looking at a rear diff overhaul with a new ring and pinion.

You’re lucky it was the rear U-joint that failed. Easy fix if the “dragging” wasn’t too destructive. Rocketman

Looks like there’s no pinion nut to hold it on.

I can guess what that ring and pinion look like and it ain’t pretty.

It’s time to have it towed to a shop and put on a lift.

You need to get this to a shop that rebuilds differentials.

How in the world did the pinion nut back off or disappear? The rear axle spline should have a nut on that threaded portion holding on the pinion yoke (the thing attached to the u-joint in the 3rd picture). That nut keeps the pinion gear tight to its bearings so it doesn’t chew stuff up inside the differential. That nut being gone means youv’e likely chewed stuff up inside the differential and as you’ve found out the driveshaft then falls off.

Have it towed with the rear lifted to a shop to have the differential cover removed and the insides checked. If you’ve lived a clean life, you might be able to replace the pinion nut, set the proper pre-load and stake the nut so it won’t come off again, replace the driveshaft and rive away. If not, get ready for a $1600-$1900 differential rebuild or have a used axle installed for $1200 or so.

I am curious. Are there actual threads still on the pinion shaft showing at the rear axle? Are they well formed or are they monged over like they were stripped by the nut? I can not discern any true threads on picture #2. Also are there any attachment bolts holding the pinion yoke (on the rear end of the drive shaft) to the universal joint cross cups? Due to the orientation of the pinion yoke I cannot see the hardware. I guess the Ujoint cross could be pressed into a solid capture yoke like for the front Ujoint but I have never seen that done.

Good camera work though.

I think the hardware is there, just hard to see. clicking on the pic enlarges and flips the photo and you can barely see the one bolt holding the saddle-clamps that hold the joint in place.

I think the yoke nut just came off causing all this. Hopefully there was no damage to the Differential.

I think you should have it towed to a shop. 1. tow with the rear raised and 2. slide the drive shaft back into the transmission spline & 3. bungie the shaft up off the ground.


Thanks for posting the photos. Interesting. It appears your configuration is different from my truck. I don’t think it is possible for that to happen w/my Ford truck b/c there’s a big fat nut that holds the front part of the differential third member to the rest of the differential. I think that nut is what the folks above are referring to as the “pinion nut”.

I agree that they are very good pictures.

I wonder if it being a 1997, that there was a leaky seal that was replaced and they didn’t torque that pinion nut…or forgotten to tighten it all together.


WOW, I’ve never seen one do THAT.

Of course there is a good chance that both of the gears (big ring, and small pinion) inside the differential are chewed up and/or misaligned due to the pinion nut getting looser and looser. If you have been living right, you MIGHT get away with buying a new pinion nut, and putting it back together. It will require taking the rear “yoke” apart from the driveshaft. It’s worth trying to save several hundred dollars. Can you do any of this yourself? If not, do you know an honest shop willing to give it a try at a reasonable cost?

Please let us know what happens.

How do I know if the differential has internal damage? How much is that going to cost to diagnose? I don’t want to pay another $125 to get it towed again and then be told it’s gonna cost $700 to open up just to take a look. I’m leaning towards totalling the whole truck right now.

Or you recommend just trying to put it back together and see what happens. Okay. I gotcha. I know the perfect guy for that, but he just went to jail. Doh.

Because of the age of the truck, I think you should just get the pinion yoke nut and try putting it back together. I would think that if it had been destroying itself as this loosened…you would have heard the rear end howling the last few days/weeks.

Have the rear jacket up for room to work and borrow some jack stands to be safe.
First thing to do is grab a can of spray paint and mark one bearing end and that ear of the yoke.
They are balanced and will vibrate if not aligned the same as before. Then slide the tranny end of the shaft back into the tranny. You may have to rotate it until it lines up and slides in.

Note; You could just pull the shaft out the rest of the way and do some of this away from the truck.

Remove the four bolts that hold the retainers on. They will be facing towards the rear and should be 10mm. Pull the retainers off and pry the u-joint out of the yoke, being careful not to let the bearing caps fall off of the u-Joint. This should seperate the yoke from the u-joint. Tape the bearing caps on so you don’t accidently knock one off and you lose the bearings.
Then slide the yoke back onto the shaft…install the new nut and tighten it down. You will probably have to reinstall the retainers and put a piece of pipe through the retainers to keep the shaft from turning as you tighten the nut.
Then remove the tape and carefully…without disturbing the bearings…slide them into the yoke and install the retainers. You may have to have the tranny in Neutral to align the yoke and u-joint again.

From the pic’s…you’ve lost some rear end lube. Any parts store can line you up with the right fluid. Remove the fill plug from the cover pan and refill until the level in the rear end allows the fluid to flow back out the plug hole.
Then check the tranny dip stick in case you lost fluid when the shaft pulled past the seal. Refill if necessary.

Take it for a drive and if the rear end is not making more noise than it always did, you should be good to go.

The one thing I would do if it’s quiet…and not vibrating and you feel confident after driving 50 miles.
I’d make an appointment to have someone replace the u-joint and torque that nut properly.
At that time they can also inspect everything to be sure there is no other damage.

Forgot to mention. If on the test drive it howles and makes a lot of noise all you’ve spent is the price of the nut and your time. Then you can decide weather you want to have it towed to a shop, or salvage yard.