[LASJayhawk]

So it was a bad day 11/12/19 for the beater 65 2+2

[AROWHED]

Damn. Pinion gear nut backed off? Were you getting driveline vibrations?

[LASJayhawk]

That’s what I think happened, the nut seems to be missing. It started making gear grinding noises de-accelerating. I was going maybe 10 mph coming up to a red light when it let go.

You’d think if I was gonna shell the rear ended it would have been at full throttle...

[stevep]

Those rears almost never break!

['ol Pinion head]

Originally Posted by LASJayhawk

That’s what I think happened, the nut seems to be missing. It started making gear grinding noises de-accelerating. I was going maybe 10 mph coming up to a red light when it let go.

You’d think if I was gonna shell the rear ended it would have been at full throttle...

Have ran across similar scenario several times with various gray iron 8.2 10 bolts. Typically was in a well used rear with low tooth count pinion (4.33's, 4.56's).

[lust4speed]

Right after we purchased the 2+2 my son was pulling off the freeway and had slowed down to about 50 when the yoke came off the pinion gear. Swished down to about 5 MPH when the pinion was pulled into the hole in the carrier. Before that it was just chewing away on the outside of the carrier case. We were lucky that the tires just slid to a stop the last few feet. Chipped all the teeth on the pinion and took quite a bit of metal off the carrier but that was it. Had to replace the 3.08 gears and the posi carrier but no damage to the axle housing. A lower gearset with a smaller pinion gear might have made its way into the hole sooner and could have changed the outcome. He didn't run over the driveshaft and found it in the weeds and we were able to reuse it after having it checked out.

My guess is that the seller had the pinion seal replaced before the sale and the shop didn't stake the nut.

[LASJayhawk]

TBH I don’t think the 2+2 is worth saving at this point. Thinking about moving the 421 tripower 4 speed setup into the 65 Cat Safari.

[Goatracer1]

Same thing happened to my son's late model PU truck.

[mgarblik]

The pinion nut working loose or coming off is the #1 cause of that failure by far. A total pinion bearing failure is a distant #2 and almost always gives lots of warning from tremendous noise. As mentioned, incorrect pinion seal replacement is the #1 cause of the nut working loose. In the old days, GM insisted that pinion seal replacement REQUIRED complete disassembly of the rear end and crush spacer replacement with the pinion seal as well as a NEW pinion nut anytime the seal was replaced. Because of the hours of time it took to do the job right, nobody did it that way and GM cut the flat rate from 3.5 Hrs. to .8 Hr. to just replace the seal. That's when the problems really started. When I replace a seal only, I mark the pinion stem and nut for reference. Then when I put it back together, load the threads with RED locktite. Tighten the nut until the marks line up. Then continue to tighten by hand only an additional 30 degrees. (half a flat on the nut) That's about the best you can do without teardown and new crush sleeve.

[marxjunk]

just swap a new rear in and torture it some more..