[P@blo]

SAE 80W90 here with GM LS additive


I listened to your video dataway and it gives me the hebejebees. Hopefully you can get it fixed before it ends up costing any down-time.

[NeighborsComplaint]

If you want to drive it a while before tearing into the diff. An old trick was draining some fluid adding a can of STP. I had a 9” Ford that began whining and the STP trick made it bearable until I pulled the pumpkin and replaced the pinion bearing. One of the Lucas additives would probably work for the interim but the STP is a sure thing to quiet it down until you dig in and inspect.

[jhein]

My problems were different than yours. I had chatter/binding of my clutches. Non-synthetic oil and the GM additive fixed that. But a whine, I don't know.

[dataway]

I've got a couple of new gaskets on the way and some more lube.

It's a very "soft" whine if you know what I mean. On hardish acceleration I don't feel or hear any "granularity".

I was thinking the other day what might have happened to it ... one unknown is that I dropped if off to have the whole thing sand blasted ... still fully assembled. At a place ...well, that you might expect to find out in the middle of nowhere. Far as I know they could have dropped the axle right on the yoke moving it around or something.

Within a day or so I'll try to post a good video of the innards rotating for better minds than my own to take a look at.

I'd be way more pessimistic if I could "feel" any problems, but up on the lift I can find no grittiness, or bearing roughness, no grinding or popping. Just the usual slop from a well worn diff.

So .... if I have to have this "rebuilt" ... I assume that means removing the axle from the car, or leaving the car at a shop long enough to have the job done? I'm VERY much a DIY kind of person, and the shop manual has a very good section on setting up the diff ... I'd be extremely tempted to do it myself. I built the entire engine and trans ... surely the diff is not such rocket science that I can't do it myself ... ??

[b-man]

You can fix anything.

Now get to it.

[dataway]

Made a video of the diff with the cover off.

I'm seeing the typical slop in the spiders from a youth full of one wheel burnouts, and I see lots of shiny wear on the spider teeth. I also see the spider gears moving outwards when they engage ... like there are worn shims on the big side of the gears.

Ring and pinion look pretty good, at least what I can see. Very little slop between the pinion and ring. The clunk when I'm turning the ring gear is the inertia of the wheels and tires which are still on driving the spiders.

Found no metal or debri in the pumpkin or oil.

But ... bad spiders wouldn't make a constant whine while going straight would they? They shouldn't even be spinning in relation to each other.

Driveshaft was still connected in this video, that's how I'm turning the ring gear.

Spiders can be easily replaced by pulling the pin correct?

Making me wonder if the whine is in the output end of the transmission. But I didn't hear it when the engine/trans was on the stand and running in gear.

https://youtu.be/dn6YRhk_GDY

[dataway]

Should I replace the spider gears while I have the cover off? Just pull the pin and slide the gears off the pin and axles right?

[steve25]

If you spin each axle by a long 3/8” drive extension spanning the lug nut studs, does one axle take more force to spin indicating one axle tube is no longer 100% perpendicular to the pumpkin?

[b-man]

I’d do the spiders and side gears at the same time.

They’re not whining it’s your ring and pinion, the pinion nut is loose now.

[dataway]

Steve, wheels/brakes are still on, so I get some small brake drag now .. but in the spots where there isn't any .. both wheels spin very freely and smoothly with no discernible difference.

b-man, I didn't realize the spider gears were just the two small (vertical) gears. Yes, I'd replace all four .... is there anything complex about that? It appears I just loosen the cross pin bolt, pull the cross pin and it all comes apart. Then just reinstall the new parts.

Going to pull the driveshaft and check the pinion over real good. I agree .. it's a pinion noise. I think you may be right that sometime during its long 40 year sleep it probably saw some kind of impact or other scenario that disturbed the crush sleeve/pinion bearing. It wasn't a progressive thing, even as a kid driving this car in the early 80's I wouldn't have driven it with that kind of noise.

Looks like I will be learning to work on the only thing on an automobile I have never rebuilt ... the differential

[Greg Reid]

Take plenty of pics. I've never worked on one either and want to follow along...I saved an old instructional article some years ago, "Don't Let Her Rear End Scare You".. or something like that.

[Shiny]

I'm sorry you have to deal with this after all you completed. You'll figure it out and are more than capable of fixing it.

I had never seen the inside of a rear axle but was able to rebuild my 8.2. I installed an Eaton posi carrier and new 3.55 gears at the time. It does not whine, at least that I can tell in the short drives I've taken.

It has been about 18 yrs !!!! but I remember it being straightforward after I read a lot. I remember two "tricky" things:

1. Pressing a new bearing on and off to adjust shims

To avoid this, I ground the ID of the old bearing so it would be a slip-fit. This saved a lot of work. I may still have that bearing. If you have an 8.2 axle and want the bearing, I'll send it to you if I can find it.

2. I did not have a low-range torque wrench needed to adjust bearing pre-load

Rather than spend a lot for a tool I'd never use again, I fabricated my own torque wrench by calibrating a rubber band acting on a fixed lever-arm distance on a breaker bar. Since the pre-load torque was a single target, I calculated the ounces force needed to achieve the in-oz torque, then measured the stretch to achieve that force.

[dataway]

Excellent ideas.
So you used the old bearing with the increased ID as a kind of calibrated spacer to test the shim pack?

I also don't have the low range torque wrench .. kinda want an excuse to buy one though.

Currently ... I'm hoping I just have to adjust the pinion nut and not replace the pinion bearing. Today/tonight I'm going to spend some quality time with the Service Manual and then go down and probably remove the driveshaft and spider gears to see how the pinion feels. Hopefully I find a loosened pinion nut that just needs adjustment. Visually the ring and pinion appear great. On a 100K mile 2.93 open diff, with an automatic, that never ran any kind of high traction tires, and no high rpm neutral drops into gear I wouldn't expect a lot of damage.

This issue really doesn't cause me any consternation, so far the car has been outstandingly free of problems (knock wood). And surely this is easier than getting a whole bunch of engine bearing clearances right

[Shiny]

Originally Posted by dataway

Excellent ideas.
So you used the old bearing with the increased ID as a kind of calibrated spacer to test the shim pack?

Yes, basically installing an oversized bearing so it can come on and off easy while adjusting the pinion depth. But I replaced the gear set and didn't have a press. If you keep the same gears, you can probably avoid this.

I also don't have the low range torque wrench .. kinda want an excuse to buy one though.

Understand and often battle similar irrational impulses...

Currently ... I'm hoping I just have to adjust the pinion nut and not replace the pinion bearing. Today/tonight I'm going to spend some quality time with the Service Manual and then go down and probably remove the driveshaft and spider gears to see how the pinion feels. Hopefully I find a loosened pinion nut that just needs adjustment. Visually the ring and pinion appear great. On a 100K mile 2.93 open diff, with an automatic, that never ran any kind of high traction tires, and no high rpm neutral drops into gear I wouldn't expect a lot of damage.

This issue really doesn't cause me any consternation, so far the car has been outstandingly free of problems (knock wood). And surely this is easier than getting a whole bunch of engine bearing clearances right

I truly hope you find an obvious issue and it proves easy to correct.

Mike

[dataway]

By the way ... does anyone know if the spider gears and side gears can be replaced with the carrier in the pumpkin?

Looks to me like the problem would be getting the cross shaft out. Could it be drilled an pulled with a slide hammer? Should be able to just tap the new one into place correct?

Side gears just slide on the axles with the thrust washers right?

[dataway]

Took the driveshaft off, my little torque wrench hasn't arrived yet but I can tell there is very little preload on the pinion.

The pinion nut is quite tight ... I wasn't able to move it (ordered a yoke holder). So I'm not sure that is the issue. Zero detectable end play in the pinion. But then I don't know how much force is necessary to tighten the pinion nut against the crush sleeve to achieve the proper preload.

Looks to me like the pinion cross shaft would slide right out if the retaining bolt is removed, I can see slight movement in the shaft so the spider and side gears probably need to be replaced, that is where the vast majority of any "clunking" is coming from.

Perhaps the pinion nut is far harder to tighten than I realize. Ring and pinion sure seem to be fine visually, if not for the whine I'd look at this rear end and say it's fine except for the spiders.

Anyone have any preferred parts sources for things like spider/side gear sets?

Is there an area of the forum where these question might get some more responses? Seems like a lot of people have Differentialaphobia like I did and are hesitant to respond.

["QUICK-SILVER"]

Cross shaft should slide out with your fingers once the retaining bolt is removed. May require a light tap to get it started out.

Yes to changing them in the car.

Yes to axle gears.

Clay

["QUICK-SILVER"]

Listening to your video, I would pull the carrier and pinion for a bearing inspection.

Never felt any resistance on a pinion if the rearend has miles on it.

Takes a bunch of torque to crush a crush sleeve. I use a big pipe wrench to hold the yoke.

Clay

[dataway]

Excellent info folks, thank you very much. Helps a ton hearing from people that have done these things.

That's what I suspected for pinion resistance ... with a 100K miles I would expect any initial preload would have settled out.

Also going to check my wheel axle bearings (new) just in case. But the whine seems to "wind up" too fast to be axle related. The outer bearings are the only thing I did to the rear end other than changing the fluid.

Does a worn pinion bearing present itself with any end play or other unnatural movement of the pinion/yoke by hand? By hand the pinion feels very smooth, no end play, no axial play. Also zero leaking from the original pinion seal.

[dataway]

OK ... made another video but the audio didn't turn out well so it's of no use.

Couple of questions about carrier bearings. How quiet should they be rotating by hand in a drained diff? Being precision tapered bearings I would expect them to be very quiet, like a front wheel bearing.

Mine are making an audible rumbling. Easily audible with my head a foot behind the diff, and very easily heard with the stethoscope touching the bearing cap. No grinding, popping, etc .. but the sound of a loose or worn front wheel bearing.

No discernable radial slop in the ring gear or anything else unnatural going on.

If I replace the carrier bearings do I have to do the whole gear setup routine, or just replace the carrier with the original shims and new bearings?

Unfortunately I still doubt this is the cause of the whine ... but sounds like it needs to be done anyway. I don't think the diff lube was changed in this vehicle since the day it left the factory ... I know I never did for 40+ years until this restoration.

List is growing ... spiders and cross shaft, side gears, and carrier bearings