Loose driveshaft?! Take a look

[MannyDantyla]

I made a 400 mile round trip drive on my 83 chevy 4x4 this past weekend, with a stop at an Off Road Vehicle area to do a little 4 wheeling. When on the highway, the truck would shake if I drove over 65 mph. After the off road fun - which included a good deal of bucking and bouncing and vroom vroom - and back onto the highway, the truck started making a loud squealing noise.

The noise is a loud metal squeal. Like a bearing went bad. But it would ONLY make the noise when the vehicle was coasting to a stop, with or without the breaks applied, with or without the clutch engaged, and with our without the tranny in neutral. If it was slowing down, it was making the noise. And the loudness is in sync with the speed of the wheels. When moving really slow, can hardly hear it. When moving fast, it's really loud. But still, it's only when slowing down.

My first thoughts where, either wheel bearing or throughout bearing. But it didn't matter if the clutch was engaged or not, and it didn't sound like the videos on youtube of bad wheel bearings. And the fact that it only makes sound when slowing down is strange....

So I thought I would check out the u-joints. I get under the truck and grab the axle and try to move it around to see if the u-joint had any play in it. It didn't move, but the yoke did! The yoke totally can wiggle a few millimeters in any direction, and there's actually 1 or 2 millimeters of daylight between the yoke and the differential body. Oil is actually dripping out a little.

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So that's got to be it. Hopefully all I'll need to do is remove the u-joint and tighten the bold behind it that bolts the yoke to the pinion. Will inspect the bearing and seal too and likely replace them. God I hope I don't have to replace the yoke and/or pinion, I can't afford that right now.

Then I looked at the other end of the driveshaft and, surprise! An even bigger gap between the yoke and the transfer case. But it's on there pretty solid, no play in any direction.

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That's not normal, is it?? You can see a ring of oil/grease that has been splattered onto the floorboards.

What should I do?

The axle is not stock. This chevy 4x4 used to be a 2WD C10 according to both the VIN number and a carfax report. So it was converted to 4wd. And I believe it used to be an automatic because there's the P-N-D-R indicators on the dashboard. Now it has a SM465 and NP205 transfer case. The 305 was also swapped for a 350 and 35" mud tires were installed.

Do you think it's possible that the SM465+NP205 was the same length as whatever auto tranny it used to have, so the PO didn't replace it with an axle that mates with a transfer case not an auto tranny...

I'm not going to replace the driveshaft if I don't have to. I wonder if I can just install some oil seal in that space between the yoke and transfer case. Or maybe one is supposed to be there and it's missing.

 

[PrairieDrifter]

I would be cautious of tightening the pinion nut, you aren't supposed to just snug it up, if you tighten that it changes the pinion depth and if your rear end has normal wear Youre going to create a bigger gap between the pinion and ring gear which will make an even worse noise and can cause some destruction.

There should be a seal on the back of the transfer case. The space between the yoke and the transfer case should just be the slip yoke just pulled out slightly

 

[MannyDantyla]

Also, is it bad to drive around with the drivetrain in this condition?

I would be cautious of tightening the pinion nut, you aren't supposed to just snug it up, if you tighten that it changes the pinion depth and if your rear end has normal wear Youre going to create a bigger gap between the pinion and ring gear which will make an even worse noise and can cause some destruction.

Then what can I do to eliminate the play in the yoke? Please don't say replace the pinion bearing. I've been watching youtube videos on how to do that and I don't think it's something I can do, and I can't afford to pay a shop.

There should be a seal on the back of the transfer case. The space between the yoke and the transfer case should just be the slip yoke just pulled out slightly

It's a fixed yoke I think. Here's a pic of the driveshaft and transfer case:

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So it's one of those driveshafts that moves in and out of it's own (doube cardan?)

 

[PrairieDrifter]

I wouldn't keep driving it if you can move the pinion. It's the front driveshaft right? And no that is not a double cardan joint. That was my fault on the slip yoke I thought you were talking about the rear driveshaft for some reason. You have the standard set up, the driveshaft in the front has a splined shaft and it comes apart in two pieces the splined shaft is how the driveshaft can extend and retract during suspension travel, while the rear driveshaft has a slip yoke that goes in the transfer case, I've seen rear two piece driveshafts with a spline shaft.

And as far as fixing it theres a lot of work and measurements and adjustments to make, so if you don't have any knowledge on how to rebuild a diff I probably wouldn't attempt it. And with that said you can find some new axles for pretty cheap that are still in good shape just make sure they're the same gear ratio. You probably just have ten bolt diffs so you could upgrade to some bigger axles and not have to worry about tearing it up so much.

But it needs to get fixed right or replaced or you'll just have bigger problems.

 

[79K10]

change ALL the U Joints! i lost one on the freeway, no bueno! smashed my tranny! grabbed all my fuel lines,brake lines running to the back, made a pretty mean dent in the frame too! (posted on here somnehwhere) dont mess around with that, change all the ujoints and see how it rides after that... my .02 lol

 

[PrairieDrifter]

This is a double cardan joint it basically reduces the angle of the driveshaft by having extra pivot points, it'll still have the splined two piece driveshaft.

 

[MannyDantyla]

no its' the REAR driveshaft!

sorry about that. remember, this truck was a 2wd to 4wd conversion

 

[MannyDantyla]

so this is what I have to do: https://www.youtube.com/watch?v=jh25DUyCWY8 great

or find a new (to me) differential.

I'm looking for the cheapest fix possible. Are you sure I can't just tighten the pinion nut?? No, I see why that would pull the pinion back towards the engine and change the way it meshes with the ring. Dammit. I just got under the truck again and wiggled the yoke some more. There's a significant amount of play vertically and horizontally, but you can also move it in and out by a few millimeters. Does this mean the pinion is moving as well??

 

[PrairieDrifter]

If you can wiggle the yoke on the differential then yes most likely the pinion is moving. Have you removed the driveshafts yet?

 

[MannyDantyla]

If you can wiggle the yoke on the differential then yes most likely the pinion is moving. Have you removed the driveshafts yet?

I do now.

After removing the axle/u-joint, I could access the nut. It was so loose I could remove it by hand, and I did. Then yoke came right off, didn't need a puller or anything. Good because I don't have one, or air tools or anything.

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Oil is now dripping out in a steady stream.

 

[MannyDantyla]

I'm grabbing the pinion by the spline and yanking it in all directions and it's not budging at all!

So maybe the bearings are alright! I was quoted $950 by a shop to do the work, and that is not an option for me right now. But before I tear it apart myself, I want to make sure it's absolutely necessary. Yes I could damage the diff by tightening the pinion bolt if it moves the pinion and changes the way it touches the ring, but I could also ruin the diff by trying to take it apart myself. This is what I'm dealing with.

I think what I'll do is drain the diff fluid and use a strong magnet to look for metal shavings in it, which would be a clue that something is wrong in there. If none then I'll fill it back up with new fluid, install a new oil seal, put the yoke back on and torque the pinion bolt to spec.

If the noise is gone, then I'm done!

 

[89Suburban]

Holy **** that was that loose it just came right off? I hope your gears aren't messed up buddy.

 

[PrairieDrifter]

Yeah that was pretty bad, as for the just tightening the pinion nut, you can't really do tat after you remove the yoke, when the pinion is installed it has a crush sleeve and it takes a lot of force to crush it at least two people. And once the sleeve is crushed to spec and the ring gear backlash is correct you can't take the yoke off and put it back on you need to put a new crush sleeve in and crush to spec, which requires full diff disassembly.

But hey you can try to reinstall it, just make sure you don't crush the sleeve anymore than it is, your backlash will change and cause destruction basically ha. You have to tighten it just enough use loctite. And if the noise goes away then that's great! But I wouldnt trust it for very long, with how loose it was it had to of caused premature wear.

 

[MannyDantyla]

Thanks for all the awesome advise guys.

So lets see what kind of damage may have occurred inside the differential...

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The teeth on the ring gear looks alright I think:

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And umm... looks like the loose pinion made some contact with the differentail assembly:

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I tried to get a shot of the pinion gears. You can kind of see what looks like a little damage:

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I dragged a high powered magnet (removed from an old computer hard drive) through the old gear old to see what it would collect. Looks like a fair amount of metal shavings:

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So, yes, there's a little damage inside the diff. But I can't afford to rebuild it right now, I'm just going to put it back together and see what happens next....

 

[MannyDantyla]

Before I put it back together, I need to replace the old oil seal with a new one. First thing I needed to do was remove the old oil seal.

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With that out of the way, I saw one of the two pinion bearings.

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It was loose in there, so I used a magnetic picker upper tool to pull it out. Figured I might as well inspect it.

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This is the OLD bearing. But it looks brand new! I wonder if the PO had replaced it because he experienced this same problem I'm having...

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It's hard to photograph, but you can kind of see the crush spacer behind the bearing race on the pinion:

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Then I simply put it all back on the way I took it off. The yoke was pressed onto the pinion spline by simply tightening the pinion bolt. I used red threadlocker, the higher strength kind, and turned the nut 1/8th of a turn pass that point where it's tight. Hopefully this didn't change the backlash camber angle tolerance whatever.

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Can you tell which part I tried to wash the grime off of