What would cause the driveshaft to just spin on a suregrip?

Was driving and had a wheel bearing fail, had the truck towed home. Now the driveshaft spins, but the truck doesnt move.

Axles are Dutchman axles, so I dont think they would have snapped. There is no grinding no noise, no nothing.

If one side goes bad on a SG will the other side not grab?

I'm sure its going to be expensive, but since I need to have it towed to a shop to look at it, I'm trying to diagnose the best I can.

Driverside is leaking (pouring) gear oil out the axle tube end at the flange/bearing area.

Stripped out splines on one or both of the differential side gears. These are the splines that engage the splines on the axle shafts. If one gives up the driveshaft will just spin.

Would very likely be making some grinding noise though.

Pull the axles and inspect the splines.

It made some noise/vibration when the bearing went bad, then after I pulled to the roadside it started oozing gear oil.

Then the dang thing wouldn't start to load on the trailer, so we went to a flatbed wrecker.

It sat here in my driveway for the past week, as I was just mad at the truck. I keep putting good parts in into it, and it keeps letting me down.

Anywho, replaced the coil and she fired up (how odd it that, the rear end craps out and the bearing goes, as well as the coil all at the same time) I may need one of those "gremlin" bells.

Now it makes no noise, you cant hear any grinding, popping, it doesn't try to catch. The drive shaft just silently and smoothly spins.

I'm considering switching to a spool rear housing. I have the high grade axles, built up trans, etc. I don't drive far when I'm out, I would be on the two lane highway for about 15 miles or so. and I have a second truck to use in inclement weather.

I hear others mention they use spools as daily drivers, on highway, in town, etc with no issue. Its a light weight 2wd short box Dakota.



This truck was supposed to be a fun cruiser, with some street pep.

how the heck does one strip the splines on the gear? Thats what really has me puzzled.

I was traveling in a straight line, on the higway, at 65mph. I had just made the drive to a town 20 miles from home, done my shopping and was returning.

The center section was a used chunk, but never had any vibrations, and visual inspection before installation to be sure the thrust buttons were removed, showed nothing odd. As assembled the differential had less than 200 miles on it, 70 miles after initial installation the right side bearing failed, one new axle, bearing, and housing later and the other side failed with 86 more miles.

Its been street driven, no brake stands, no sticky tires. its behind a 5.2 auto in a Dakota.

I'm trying to figure out the root cause, so I can avoid it.

I have put many, many 8-3/4's through some rather intense abuse, and never had a failure like this.

The most frustrating part is if I was beating on the thing I could understand it breaking, but that was not the case here.

Only one way to find out what happened.

Open it up and look.

Anything else is guessing. But it sounds to me that whomever did your rear end work didn't do it right.

Possible causes:

1. Axle splines not engaging the side gears
2. Axle splines and/or side gear splines stripped
3. Spider gears broken
4. Axles broken

I'm guessing the side gear splines are stripped inside the sure-grip.

I don't understand why you are also leaking gear lube around the wheel bearing.

Did you check the housing for straightness?

We did check the housing to be sure it was straight. This is a new housing, not the original one used when the first bearing decided to leave.

Its frustrating thats for sure. I have never had this sort of luck with an 8-3/4 before.

Wow! This is the first time I ever heard of a 8.75 axle failing like that. Good luck with it. I hope you get it repaired quickly.

Not that it makes any sense but the pinion may be broke as well, so if it will move in and out any.

It will be a week or two before I can get it in to the local shop to have it disassembled to see exactly what failed.

Are you sure your axles are engaging into the diff? If you have changed housings, make sure the new housing is the same width as the original one.

The axles were made to fit the new housing. Even made slightly longer than stock for maximum engagement since Ihave no thrust bearing shims.

Any news?

No update?

If it makes you feel any better,the guy the thing came from went to jail for a few months right after you bought it .

No reply......Mark Nixon???????????

I had a clutch type do that before. It was whining and would barely move, I thought it was the trans, rebuilt it and the same thing. Then we saw the driveshaft spinning and the wheels not moving.
I still haven't pulled the sure grip apart to check it out.

No matter how worn, or non-functional a sure grip is, it will still act like an open diff. As stated, if you have stripped or broken stuff it may not move. But no matter the type, sure grips and posi's and others wear towards being an open diff.