Question for BigTen, 71 Chevy Malibu 12 bolt rear axle bearing vertical play

Sharps40

Old Mossy Horns
BigTen,

I'm working on my 37 Dodge Sedan. 1971 Chevy Malibu 12 bolt 3.31 open rear. Used, unknown mileage. Ring and pinion gear looked good, no chips/cracks/galling but did not check wipe. New 80/90 lube.

Got the exhaust in place and things are quiet enough to hear whats going on.

From the rear is a grinding scraping sound, like drums and shoes rubbing, but worse/louder. More of a metal on metal sound. But all new brakes out back and I checked, no rubbing. Sound does not stop on application of brakes.

Had the wheels off today. No leaks at axle stubs or pinion.

However, axles can be moved up and down more than 1/8". Hard to measure but probably less than 1/4" of up and down movement. In out movement is about what I'd expect, 1/8" or so.

I know its probably a well used axle and could have issues in the center section but the question is:

Is the vertical play I see on both sides excessive and if so, indicative of worn out outer bearings?
 

nccatfisher

Old Mossy Horns
Contributor
Axle bearing should be a whine, much like the sound deep tread tires make on a truck. If you get on a smooth road you should be able to hear them sing if they are going out.
 
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QBD2

Old Mossy Horns
Axle bearing should be a whine, much line the sound deep tread tires make on a truck. If you get on a smooth road you should be able to hear them sing if they are going out.
Agreed, but if he can move the axle 1/4 inch at the end of the tube, they’re prolly past whining.
 

nccatfisher

Old Mossy Horns
Contributor
Agreed, but if he can move the axle 1/4 inch at the end of the tube, they’re prolly past whining.
True, but at that point oil should be pouring out of the seals because if there is that much lateral movement there would have to be some vertical movement also.
 

Sharps40

Old Mossy Horns
"However, axles can be moved up and down more than 1/8". Hard to measure but probably less than 1/4" of up and down movement. In out movement is about what I'd expect, 1/8" or so."

no leaks..noisy but just up/down seems excessive...lateral seems ok.

I reckon BigTen will chime in too. I think I know what he'll have to say
 

bigten

Old Mossy Horns
Contributor
You should not have any vertical movement with either axle. That much movement is not normal. I can ride over at your convenience to look at things so we can figure the issue and a fix..
 

Sharps40

Old Mossy Horns
I knew you'd say that!

Let me try to get title inspection this week and then I can park it , get it on stands and we can pull an axle. I see axle kits with bearings, seals and lug studs at jegs and summit. With luck a partial rebuild wi hold it a while. If I need gears I want to switch to 3.08 but that's another job.
 

Sharps40

Old Mossy Horns
This is it, found this video and essentially this is what my rear hubs do but without leaks and without overheating. New axle and bearings time I'm sure. I'll still pull the shafts to look but betcha at least the outers are shot and prolly the shafts too.

 

bigten

Old Mossy Horns
Contributor
I'm afraid with the vertical movement you have, the axles may be worn. We can keep our fingers crossed it is just bearings though. The axle runs directly on the bearing rollers acting as the inner race, so that possibility is there. Let me know when you want to get in it as I have a few days open next week while between trips..
 

Sharps40

Old Mossy Horns
Updating. Video of my axles. I'll follow with photos of the shafts. One is worn 2 thousands groove. Driver side is worn 40 thousands groove! Driver side bearing is loosy goosy too!

 

Sharps40

Old Mossy Horns
Axles, bearings, seals and a new differential cross pin ordered. I find no movement what so ever in the pinion, so, remain hopeful. photos of the worn out driver side axle stub and the worn passenger side axle stub. Naturally, the bearing on the driver side is way sloppier than the passenger side too.


20200809_103909.jpg20200809_103920.jpg
 

bigten

Old Mossy Horns
Contributor
Eeh! Yea, that's not good... but what I was afraid would be found. Will need to bring my bearing puller over..
 

Sharps40

Old Mossy Horns
The really bad axle has a 40 thousand groove in it. Other one is .002. I figured no sense trying an axle saver bearing since the wear is serious. Called jegs and have 2 new axles with bearings, seals and lug studs inbound. And the factory rollers are lots easier to get in and out than the axle saver bearings.
 

Sharps40

Old Mossy Horns
Thanks BigTen,

After a short wrestling match, BigTen managed to yank out a normal chevy bearing and seal assembly on the passenger side, and a Demonically tight Saver Bearing and Seal on the drivers side. Both bearings wanted to stay in place, but.....they lost the fight. New axles and bearings/seals are in and just awaiting the new spider cross pin to oil her up and go for a test ride.

20200813_140427.jpg20200813_140434.jpg20200813_142001.jpg20200813_115448.jpg
 
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Sharps40

Old Mossy Horns
Finally got the new cross pin for the differential. This is the original. (.805 original dia. .803 across the gauled ends. New yukon pin is .808.) Looks like hi mileage and maybe a few burn out or run a bit hot. New pin fits much better and is installed. It's about all I can do for now on the rear. A test ride tomorrow will indicate if the new pin, axles and outer bearings is enough for now. Fingers crossed.......

20200814_133556.jpg
 

Sharps40

Old Mossy Horns
Update. Success.

Much quieter, no more cyclical grinding noise. Vibration is gone, at least enough that I can call out rough roads as the culprit for most of it, smooth stretches are smooth. Probably just add a bit more pinion shim next and see how she likes it.

Center section is as quiet as you could expect a 49 year old center section to be. Some noise but nothing that I plan to worry about for a year or so of driving while I focus on other needs for Ol Bessy.

Guess with the 5 window business coupe coming its time to clean the Tbird and get her on consignment over the next few weeks.

Thanks BigTen, great to have a ready and expert helper.
 
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