Rear axle failed 2005 Silverado

[350Rocket]

I just hit 250k miles and the last few days my truck started clunking in the rear at low speed over bumps, as the truck sways side to side. Some inspection revealed a lot of play in the axles. Including side to side play in both rear wheels. I have not pulled the diff cover yet, but I was sent to a local reputable transmission guy, known by several of my former coworkers from the automotive world.
He believes based on my symptoms that the carrier is worn out and it wouldn't be worth rebuilding because in his words "those one don't fail very often, we see Rams and Ford's a lot, but there's so many of those trucks out there that it doesn't make sense to spend the $ rebuilding when you can put a used one in".
So I'm still driving it for work (gently) but trying to find a good complete rear diff. It's easier to find the older ones with disc brakes so it's likely going to have to have the brakes swapped.
Most of the donor vehicles are going to be extremely rusty, while mine is not rusted at all. Brake lines are perfect back there.
Looking for suggestions (especially from clinebarger) on what I should do. I found a $200 diff last night and drove out to get it but it turned out to be 3.73 and I need the more common 3.42. Not everyone is willing to do internal work on them and even if they are, tearing into it could be expensive.
The scary thing is the 4L60E could fail the week after, as it's also original, along with the entire rest of the drivetrain.
Comments or suggestions welcome. Thanks.

 

[MSCH]

it makes noise over bumps? what sort of noise?

no gears making whining noises?

 

[PontiacHO]

Honestly doubt you could have enough wear in the diff case to feel the truck “sway”. I assume your guy is referring to the side gears in the case? Axles and axle bearings are wear items and usually are heard roaring as well as carrier and pinion bearings. I’ve seen the pin that centers the rear axle on the leaf spring break (rust) and create the swaying sensation because the axle tube isn’t being held stationary. Check all the mounting points at spring eye bushings etc.

 

[supton]

2wd? gear change should be an easy reprogram, right? I guess if you don’t tow then it is preferable for the mpg.

I agree, check suspension, but I would think you could check axle play by jacking up one wheel and grabbing it. The is a little play from the c clip, but not a lot.

 

[Rat407]

You can search www.car-part.com to look for a low mileage axle. There are plenty of GM's out there with over 300k on original drive-train.

 

[weaponoffreedom]

It is not really that big of a deal to change carrier bearings on a G80, should not be that big of a thing. I am assuming you keep up with the maintenance, and the truck is not a rust bucket?

 

[350Rocket]

it makes noise over bumps? what sort of noise?

no gears making whining noises?

No gear noise that I can hear over the duratracs and the wind noise....I know gear noise because my Cutlass has had it forever.
It's clunking when the rear is shifting side to side and you can hear and feel it if you grab the wheel and rock it.

 

[Lubener]

I would not condemn it until I pulled the cover for a look see. Could be a wheel bearing.

 

[atikovi]

I found a $200 diff last night and drove out to get it but it turned out to be 3.73 and I need the more common 3.42.

Not a big difference. I'd use it if it's a good deal.

 

[350Rocket]

Honestly doubt you could have enough wear in the diff case to feel the truck “sway”. I assume your guy is referring to the side gears in the case? Axles and axle bearings are wear items and usually are heard roaring as well as carrier and pinion bearings. I’ve seen the pin that centers the rear axle on the leaf spring break (rust) and create the swaying sensation because the axle tube isn’t being held stationary. Check all the mounting points at spring eye bushings etc.

Sorry, it's not swaying excessively, the clunking is heard during normal swaying while driving over bumps and especially rough terrain.
The play in the axles is felt by jacking it up and grabbing the wheels to check.

 

[350Rocket]

Not a big difference. I'd use it if it's a good deal.

It's 4 wheel drive. Doing the front diff would be more expensive than the rear. Not in my budget right now. If it was 2wd I would gladly upgrade to 3.73 gears as I currently leave it in 3rd most of the time so it's not downshifting on every little grade with all the weight in it.

 

[350Rocket]

It is not really that big of a deal to change carrier bearings on a G80, should not be that big of a thing. I am assuming you keep up with the maintenance, and the truck is not a rust bucket?

I was told the carrier itself could be worn out which would be over $2000 (Canadian) to fix. But yes maybe I should have them pull it apart to check and if it's no good, then get a used diff (about $600 from a wrecker with a 30 day warranty).
It's not a rush bucket. Frame is mint. Cab corners and rocker panels are new, along with one fender. Needs the passenger fender replaced in the next year, along with the rear bumper. Always will be some rust here but this truck is way better than average.
I got it from my boss at 192k miles. I've maintained all the fluids since then but before that it only had transfer case fluid and front diff fluid changed once. The rest was likely factory fluids. However the engine and trans currently work perfectly along with 4wd. Engine uses almost no oil in 5k miles but it still has the original intake gaskets, knock sensors (common issues) but they have not failed yet.
Only the water pump and a valve cover have been replaced and a purge solenoid for a check engine light.

 

[atikovi]

It's 4 wheel drive.

But part time no? When in 4WD you're on slippery roads anyway so does the difference between front and rear axle ratios matter all that much?

 

[350Rocket]

But part time no? When in 4WD you're on slippery roads anyway so does the difference between front and rear axle ratios matter all that much?

It has to be the same. It doesn't have free wheeling hubs, so parts are always turning in the front end also.

 

[D60]

Never heard of 3.42 being "more common." 3.73 is the common ratio, esp for a 4wd

ANYWAY, if you had any understanding of what is allegedly happening, you wouldn't be driving it. But I'm not convinced the diagnosis is accurate.

This is also complicated by the fact that we're not getting concise information. What is "play" in the axle(s)? Is this end play, ie straight in and out? Or is this like slop from a trashed wheel bearing, ie you can grab at 12 and 6 and rock the wheel? And if the latter, is the movement at the end of the axle tube (at the wheel bearing itself), or is the bearing a fulcrum and you can feel the splines in the carrier rocking?

Again, we've got vague info and a vague diagnosis so far. Good luck with all that.

 

[D60]

Also I would absolutely pull the cover AND the pop the c-clips and pull the axles. This would be a bare minimum before condemning the entire axle and is easy to do.

From here you can inspect-- with a relative degree of accuracy -- wheel bearings, bearing surface(s), c-clips and c-clip grooves, side gears, carrier bearings and even pinion bearings

 

[D60]

Honestly doubt you could have enough wear in the diff case to feel the truck “sway”. I assume your guy is referring to the side gears in the case? Axles and axle bearings are wear items and usually are heard roaring as well as carrier and pinion bearings. I’ve seen the pin that centers the rear axle on the leaf spring break (rust) and create the swaying sensation because the axle tube isn’t being held stationary. Check all the mounting points at spring eye bushings etc.

We're gonna hope not. The leaf pack center pin is merely a guide for assembly and a "tiny clamp" to keep the leaf pack together for handling purposes. It should have no significant load on it in actual use because the u-bolts take 99.999999% of any loading merely by providing incredible clamping force. Most center pins are 3/8" thread at best and not meant to put up any sort of a fight relative to the loads necessary to keep an axle located.

That said, yeah, it's possible OP's u-bolts loosened up for some reason and that pin sheared as a result.

 

[atikovi]

It has to be the same. It doesn't have free wheeling hubs, so parts are always turning in the front end also.

I'm not sure how that all works, but if the front isn't connected to the rear, why would that be a problem?

 

[weaponoffreedom]

@D60 I agree 1000%. Barring full rust rot, or the like, or the one thing that the OP leaves out.......

 

[350Rocket]

Never heard of 3.42 being "more common." 3.73 is the common ratio, esp for a 4wd

ANYWAY, if you had any understanding of what is allegedly happening, you wouldn't be driving it. But I'm not convinced the diagnosis is accurate.

This is also complicated by the fact that we're not getting concise information. What is "play" in the axle(s)? Is this end play, ie straight in and out? Or is this like slop from a trashed wheel bearing, ie you can grab at 12 and 6 and rock the wheel? And if the latter, is the movement at the end of the axle tube (at the wheel bearing itself), or is the bearing a fulcrum and you can feel the splines in the carrier rocking?

Again, we've got vague info and a vague diagnosis so far. Good luck with all that.

I can grab the wheel at 9 and 3 and rock it and also at 12 and 6.
And I've personally looked at all the trucks we had for work, a 2002 2wd and this truck and a 2013 4wd and a friend's 2001 2wd and all were 3.42. This parts truck was a z71 and it's the first time I've personally seen a 3.73, so that's why I came to the conclusion it was the most popular. I could be wrong, but I've looked at a lot of them.