Rear End advise: 2004 Silverado 1/2 ton

[Keitha]

Advise needed: My son lives in Las Cruces, NM (in college). He drives a 2004 Silverado 1/2 ton, 4x4. It has a stock 10 bolt with a G80 and 3.73 gear.
The rear end sounds like it may be giving him problems - turning on sand, he said if felt like he was on wash-board road. Got better when he straightened out.
I want to be ready to help him if the rear end fails. He drives on sandy desert trails a decent amount. What is the best upgrade?
- Does anyone have a 14-bolt 6 lug for sale in the Southwest?
- Is there a good differential that would work well in the 10 bolt?

The truck is low milage and in great shape. I don't mind helping him upgrade.

He does not have a garage to do any work, so I will have to help him find a shop etc.

I just had to rebuild my 14 Bolt SF on my 1991 Suburban. I spent a small fortune, but upgraded to a TrueTrac. I just don't know much about the 10-Bolts

Thanks much,

 

[tarussell]

As you know the Gov-Loc leaves a little bit to be desired in the durability department - also, the 30-splined ones sometimes break the thinner bearing journals on the carrier.

The aftermarket gear, cone or clutch type diffs have a much better reputation for not dying an early death.
That being said putting money and effort into a 10B ( the smallest axle GM ever put in a full-size truck - just something to ponder ) might leave ya feeling less than joyful.
A S/F 14B sounds like a great plan - it’s the rear axle that GM should have used in half tons all along.

 

[Blue85]

I would first figure out what's wrong. Best-case scenario is broken spider gears, which could be replaced in a parking lot. Swapping to a different axle could get expensive at a shop that will have to source all of the parts. Find out what all has to change and make sure everything is together ahead of time, like U-bolt plates, adapter U-joint, brake hoses, parking brake adapters, whatever. Hopefully there is a year of axle that has the same mounts on it and you can find one with 3.73 (is that a coil spring/trailing arm rear or leaf springs?) Obviously, it has to be a 6-lug and obviously, this all has to be figured out before proceeding.

Then there's the obvious easy button, which is just finding another 10-bolt. Sure, they're not a Dana 70, but they can go up to several hundred thousand miles under these trucks and there's lots of them out there. If it lasts through college, maybe that's better timing to do a more extensive project? The unknown with any used axle (10-bolt or 14-bolt) is the condition of wear items like bearings, brakes and seals. I don't know if the 14-bolt uses any brake parts in common with the 10-bolt of that era, but one advantage of staying 10-bolt is you could migrate known good parts from the old one, like rotors and calipers.

Repairing the axle is almost certainly possible, and eliminates the logistics of finding and transporting another axle assembly. While certainly not cheap, it may give more reliability and peace of mind than a used axle in unknown condition. If a shop is doing the work, they should be able to give you pricing on the rebuild vs replace. Again, it all starts with knowing what's wrong.

 

[tarussell]

I would first figure out what's wrong. Best-case scenario is broken spider gears, which could be replaced in a parking lot. Swapping to a different axle could get expensive at a shop that will have to source all of the parts. Find out what all has to change and make sure everything is together ahead of time, like U-bolt plates, adapter U-joint, brake hoses, parking brake adapters, whatever. Hopefully there is a year of axle that has the same mounts on it and you can find one with 3.73 (is that a coil spring/trailing arm rear or leaf springs?) Obviously, it has to be a 6-lug and obviously, this all has to be figured out before proceeding.

Then there's the obvious easy button, which is just finding another 10-bolt. Sure, they're not a Dana 70, but they can go up to several hundred thousand miles under these trucks and there's lots of them out there. If it lasts through college, maybe that's better timing to do a more extensive project? The unknown with any used axle (10-bolt or 14-bolt) is the condition of wear items like bearings, brakes and seals. I don't know if the 14-bolt uses any brake parts in common with the 10-bolt of that era, but one advantage of staying 10-bolt is you could migrate known good parts from the old one, like rotors and calipers.

Repairing the axle is almost certainly possible, and eliminates the logistics of finding and transporting another axle assembly. While certainly not cheap, it may give more reliability and peace of mind than a used axle in unknown condition. If a shop is doing the work, they should be able to give you pricing on the rebuild vs replace. Again, it all starts with knowing what's wrong.

All very valid points.
I missed the part of taking it to a shop - that could get expensive quickly!

 

[dyeager535]

If it were me, I'd find a ten bolt in a wrecking yard, take the cover off, ensure it looks and sounds good when rotated by hand, is the right ratio, ensure it's not a gov-lock, and swap it over.

10 bolts generally last pretty well when they aren't gov-locks. He's going to lose some traction (assuming it's actually working somewhat now) but unless you want to dump a ton of money into it, I'd recommend the ten bolt.

I presume that vintage if you could pick a complete donor truck with 14SF apart for minimal cost, getting almost all the components for the swap wouldn't be super costly..but I dont think I'd do so if it wasn't to keep the G80. If it's a forever truck, dump the money and effort into a 14SF. Just to get down the road, 10 bolt open. For longevity and harder use, 14SF.

Open diff on a 14SF kind of defeats the purpose of the swap if you ask me.

 

[Keitha]

I think the best advise I got from this is to take the easy route for now. I'm in SoCal - he is over 700 miles away, so it makes it tough to help hands on. On top of that, he just doesn't have the time (plays football and school) or facility to do the work.
The sandy desert conditions on the trails where they live is so hard on the G80 - lots of wheel spin.

I will keep my eyes open for a good 14BSF. I don't mind driving one out to him if I find one. His truck is super low miles, so worth investing in a good upgrade.

Hopefully it holds together for a while longer. He said it hasn't made anymore noise. It may have just been the locker -locking and skipping around the turn.
thanks for all the advise.

 

[6872xtc]

From what I have seen, the 10 bolts under the GMT800 trucks are pretty good, except for the G80. There are lots of guys running a good amount of power through them, but none keep the G80.
We pulled one out of an '01 with 300K on it with 3:73 gears and no G80, when we swapped the truck to 4:10s.
My bet is that your son's truck is locking the G80 and then NOT unlocking. My son had this happen with his '03 Dmax with the 11.5. It was very noticeable at slow speeds.
He has a Truetrac in it and his '01 now. Very happy with both!

My possibly unpopular suggestion would be to buy a Truetrac and swap it in with the original ring gear. (If the pinion is tight)
Then the only set up is measuring the backlash and returning to the same backlash with the new differential.
I say this because I don't know how easy it will be to find a complete axle without a G80, for a truck. SUV axles, of course, don't bolt in because of 4 link and coils or airbags.

 

[Keitha]

From what I have seen, the 10 bolts under the GMT800 trucks are pretty good, except for the G80. There are lots of guys running a good amount of power through them, but none keep the G80.
We pulled one out of an '01 with 300K on it with 3:73 gears and no G80, when we swapped the truck to 4:10s.
My bet is that your son's truck is locking the G80 and then NOT unlocking. My son had this happen with his '03 Dmax with the 11.5. It was very noticeable at slow speeds.
He has a Truetrac in it and his '01 now. Very happy with both!

I recently put a Truetrac in my '91 Suburban 14 bsf. I haven't had a chance to really use it yet, but I did pull my boat at the launch ramp and never knew it was there - in a good way.
I'll look into this option for him. It's a really nice, very low milage truck - I just wish it was a 3/4 ton. He's not running huge tires, so maybe the 10 bolt w Truetrac would last a good while.

 

[tarussell]

True Tracs are good diff’s !
If I had a 10B/14B-SF that would be my differential of choice.

 

[Greg Ducato]

We see a lot of trucks come into the shop with those symptoms. If there is no real noise and maybe just a popping sound on a tight turn, I would add a bottle of limited slip diff additive to the system and go to a parking lot and cut a few low speed figure eights. Always start with the cheap and easy, it works more often than you would think.

 

[dyeager535]

I recently put a Truetrac in my '91 Suburban 14 bsf. I haven't had a chance to really use it yet, but I did pull my boat at the launch ramp and never knew it was there - in a good way.
I'll look into this option for him. It's a really nice, very low milage truck - I just wish it was a 3/4 ton. He's not running huge tires, so maybe the 10 bolt w Truetrac would last a good while.

Just me, I'm not sure I'd put a ~$700 diff into a 10 bolt.

That's a lot of money to put into a marginal axle IMO. A 14SF true-trac would to me be a far better option, but I haven't checked what their cost is vs. the 10 bolt.

I've been keeping my eyes open for a cheap front ten bolt True-trac, but that's a different story. Cheap and true-trac don't generally go together from what I'm seeing lol. But I also think its one of those cost vs. quality things. I don't see a lot of people talking about their true-tracs having issues, and I expect they've got a lot into the machining and materials.

 

[6872xtc]

Lawrence LT Tolman is still using a stock rear axle with a Truetrac behind a turbo charged 8.1.
He finally broke the pinion yoke during Drag week. Chasing 11 second ETs.
I don't see that as a marginal axle, personally. I have watched him beat on it for several years.

 

[Blue85]

I don't see that as a marginal axle, personally. I have watched him beat on it for several years.

Yeah, but he probably cheated and topped the oil off more than every 200,000 miles.

 

[6872xtc]

Yeah, but he probably cheated and topped the oil off more than every 200,000 miles.

You're supposed to???
Crazy!

My point with that video is just to show what I feel is the weak point, the G80.
There are many more whom have made videos of ditching the G80 and using them hard!
I have a friend who swapped an 8.1 into a shortbed standard cab. Pulled the G80 and put just a posi type differential into it. Over 3 years and still going, even to the drag strip.

 

[dyeager535]

You're supposed to???
Crazy!

My point with that video is just to show what I feel is the weak point, the G80.
There are many more whom have made videos of ditching the G80 and using them hard!

That is fair, all problems I can think of with the 8.5 in trucks has to do with the G80. There is seemingly no problem with the 8.5 in any car applications I can think of (up to the GNX) track or not, as cars didn't get the gov-lock.

However the use case is also a determining factor. That which lives on the track may not in the 4wd world.

If the 8.5 was "enough", it would be the only axle GM ever used in trucks. Open or not, it wasn't. I'd have to watch the whole video, but I presume he's not hauling 1500lbs of gravel in the bed or using it for other "truck things"? It would definitely be interesting to know how hard you can use an 8.5 in typical truck applications. 8.5 against a Duramax towing a 15k trailer maybe?

 

[6872xtc]

That is fair, all problems I can think of with the 8.5 in trucks has to do with the G80. There is seemingly no problem with the 8.5 in any car applications I can think of (up to the GNX) track or not, as cars didn't get the gov-lock.

However the use case is also a determining factor. That which lives on the track may not in the 4wd world.

If the 8.5 was "enough", it would be the only axle GM ever used in trucks. Open or not, it wasn't. I'd have to watch the whole video, but I presume he's not hauling 1500lbs of gravel in the bed or using it for other "truck things"? It would definitely be interesting to know how hard you can use an 8.5 in typical truck applications. 8.5 against a Duramax towing a 15k trailer maybe?

I would never suggest hauling 15K lbs with a Duramax and an 8.5 axle. I don't understand why you are suggesting that idea. And I wouldn't suggest using a 14B under the mixer trucks at my work. Different applications.

No, LT isn't hauling weight with his truck, or the AWD supercharged one that he built, raced and then sold, which still had an 8.5 rear axle. However he is sending more than twice the power to the differential than the factory intended with a 5.3 engine.
The truck that my son has, used to be a company truck at my work. The guy that had it last, used it like a truck and even hauled hay for his horses after work. And running around in a gravel pit daily, it was in very good condition at 300K when we pulled it out to go 4:10.
So the original truck referenced in this thread, is probably not hauling lots of weight and shouldn't need a bigger axle with the 5.3 engine.

I still say that the G80 locked up temporarily in this young man's truck while he was running around on a gravel road. And since it unlocked and hasn't been a problem since, why condemn the whole series of axles?

 

[CyberSniper]

An open-carrier 8.625" with a Powertrax No-slip in it will take all the abuse a normally aspirated 5.3L can dish out. The weak link at that point is the pinion bearings. If you go to shims instead of a crush sleeve it'll last until you get tired of the knife-edged splines on the shafts.

 

[Keitha]

I still say that the G80 locked up temporarily in this young man's truck while he was running around on a gravel road. And since it unlocked and hasn't been a problem since, why condemn the whole series of axles?

You are spot on. He hasn't had any problems since.

IF it does go bad, the decision to rebuild the 10-bolt with true-trac is equally driven by the fact that he is >700 miles away from me and doesn't have the time to source and install anything else. It would have to go to a shop for a rebuild.
The G80 seems to go bad when they stomp on the gas with one wheel spinning and it locks instantly at a high load. True-trac eliminates that week point and would likely be good for the light duty desert / trail driving they do. At the end of the day it's still a 1/2 ton with a 4L60e and won't be pulling much or really carry any heavy loads.
It's not my ideal solution, and not the cheapest, but likely the most realistic. Let's hope the existing one doesn't break!

 

[6872xtc]

You are spot on. He hasn't had any problems since.

IF it does go bad, the decision to rebuild the 10-bolt with true-trac is equally driven by the fact that he is >700 miles away from me and doesn't have the time to source and install anything else. It would have to go to a shop for a rebuild.
The G80 seems to go bad when they stomp on the gas with one wheel spinning and it locks instantly at a high load. True-trac eliminates that week point and would likely be good for the light duty desert / trail driving they do. At the end of the day it's still a 1/2 ton with a 4L60e and won't be pulling much or really carry any heavy loads.
It's not my ideal solution, and not the cheapest, but likely the most realistic. Let's hope the existing one doesn't break!

Good plan!
Just keep the previous video from LT in mind. Add to it that so far, my son hasn't broken his. He has a 6.0 with a decent cam in it, 2700 RPM stall speed in the convertor. And when he was learning what the transmission controls would do with what he did inside the transmission, he accidentally had it slamming gears for an afternoon until he figured out what to change in the computer.
Rear end is still happy!