Why no limited slip differential on my truck

[tomseeley]

I just bought a my first new used truck. A 2002 GMC Sierra 2500HD crew cab 4x4 duramax/ally. I found it by sheer luck at a dealer while browsing an ext cab model I really wasn't interested in. After having it inspected, and all the usual stuff one does with a used rig, I bought it.

 

After I drove it home I deciphered the list of RPO codes in the glove compartment, and only then found that the truck LACKS code G80, "axle positraction limited slip". In my online shopping for a truck, I had decided that was an option I wanted, but I seriously doubt that I would have turned down the truck once I found it just because it lacked that feature.

 

My question is: in a truck equipped such as mine is, is it logical for it NOT to include the limited slip rear axle? I'm no truck expert at all. Is there something in the combination of diesel, allison, and 4x4, for example, that makes it unnecessary to ALSO include the limited slip rear axle? I guess, finally, my question is, since I plan to tow a travel trailer about 25% of the time, do I really need it after all?

[BBSilverado]

I just bought a my first new used truck.  A 2002 GMC Sierra 2500HD crew cab 4x4 duramax/ally.  I found it by sheer luck at a dealer while browsing an ext cab model I really wasn't interested in.  After having it inspected, and all the usual stuff one does with a used rig, I bought it. 

 

After I drove it home I deciphered the list of RPO codes in the glove compartment, and only then found that the truck LACKS code G80, "axle positraction limited slip".  In my online shopping for a truck, I had decided that was an option I wanted, but I seriously doubt that I would have turned down the truck once I found it just because it lacked that feature.

 

My question is:  in a truck equipped such as mine is, is it logical for it NOT to include the limited slip rear axle?  I'm no truck expert at all. Is there something in the combination of diesel, allison, and 4x4, for example, that makes it unnecessary to ALSO include the limited slip rear axle?  I guess, finally, my question is, since I plan to tow a travel trailer about 25% of the time, do I really need it after all?

 

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The G80 was and is an option, so many different combo's may not have it. Though your right in thinking as most D/A HD's had them is was not a standard. If your like me the worst part about not having an option is the fact that you know you don't. You will always wish you had it just because you know that you don't even if you never really need it.

[Jacqson]

I just bought a my first new used truck.  A 2002 GMC Sierra 2500HD crew cab 4x4 duramax/ally.  I found it by sheer luck at a dealer while browsing an ext cab model I really wasn't interested in.  After having it inspected, and all the usual stuff one does with a used rig, I bought it. 

 

After I drove it home I deciphered the list of RPO codes in the glove compartment, and only then found that the truck LACKS code G80, "axle positraction limited slip".  In my online shopping for a truck, I had decided that was an option I wanted, but I seriously doubt that I would have turned down the truck once I found it just because it lacked that feature.

 

My question is:  in a truck equipped such as mine is, is it logical for it NOT to include the limited slip rear axle?  I'm no truck expert at all. Is there something in the combination of diesel, allison, and 4x4, for example, that makes it unnecessary to ALSO include the limited slip rear axle?  I guess, finally, my question is, since I plan to tow a travel trailer about 25% of the time, do I really need it after all?

 

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The G80 was and is an option, so many different combo's may not have it. Though your right in thinking as most D/A HD's had them is was not a standard. If your like me the worst part about not having an option is the fact that you know you don't. You will always wish you had it just because you know that you don't even if you never really need it.

 

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You know that's odd because when I bought my 02 Burban (new) the G80 was standard and not an option on my truck. However it was an option in 03 for the Burban. I have a G80 unit with 5K on it in my Garage that I would like to sell but it is made for the 9.5" ring gear and the HD uses the 10.5" ring gear.

[jake111]

I believe the G80 is an automatic locker and not a limited-slip differential. So it runs open until one rear wheel slips too much, then it locks. (There are other threads which discuss what it takes to unlock.)

 

I can't see where you would have any problem towing normally, unless you go off-road and the sand gets so deep that 4x4 with open diffs isn't enough to get you through it (i.e., 1 front and 1 rear wheel spin, worst case). With the G80 under the worst case you'd have to get both rear wheels and 1 front wheel spinning before you got stuck.

[Snow Shovel]

I'd expect a truck like yours to come with limited slip. It is a very inexpensive option, especially compared with some of the other desirable options on your truck.

 

That said, just yesterday I was at a dealer browsing window stickers for new trucks and was taken at some of the odd combination of options. LTs and trucks with DuraMax but without 4wd. If someone was going to spend that kind of money for a new truck, why would they skimp on a useful?

 

I know this is all personal preference, but I'd want limited slip or 4wd before I'd want leather seats or OnStar.

[snoman]

I have a G80 unit with 5K on it in my Garage that I would like to sell but it is made for the 9.5" ring gear and the HD uses the 10.5" ring gear.

 

 

Actually the model in the start of this thread uses a rear end with a 11.5 inch ring gear not a 10.5 inch one.

[Trouttrooper]

For 2005 models the G80 is standard on the 3500 srw and optional on 2500HD. If you get the "special" D/A package on the 2500HD it included the G80.

 

My guess is there is probably quite a few 2500HD w/ D/A that doesn't have a G80.

 

You can get into quite a bit of off-roading without a locker and not get stuck. Having one is definitly nice, but not extremely necessary. I've been 4X4ing in the Rockies all my life and this is the first truck I've ever had that has a locker. It's most beneficial when you're doing a lot of twisting and such where you end up with a tire in the air.

 

A good set of mud chains can pull you through darn near anything.

[snoman]

I have run a few plow trucks for many many years and I get them without posi unit because I do not want to easily fishtail and lose directional control on slick surfaces I run on sometimes. Never really missed it either but a selectable locker that is a open diff or locked on demand would be great.

[Jacqson]

I have a G80 unit with 5K on it in my Garage that I would like to sell but it is made for the 9.5" ring gear and the HD uses the 10.5" ring gear.

 

 

Actually the model in the start of this thread uses a rear end with a 11.5 inch ring gear not a 10.5 inch one.

 

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I have the complete parts catalog in front of me and the exploded diagram of the FF axle for the CK2(HD) series of truck 00-04 and the only ring gear size listed is 10.5" and that includes the LB7 option.

[snoman]

I have a G80 unit with 5K on it in my Garage that I would like to sell but it is made for the 9.5" ring gear and the HD uses the 10.5" ring gear.

 

 

Actually the model in the start of this thread uses a rear end with a 11.5 inch ring gear not a 10.5 inch one.

 

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I have the complete parts catalog in front of me and the exploded diagram of the FF axle for the CK2(HD) series of truck 00-04 and the only ring gear size listed is 10.5" and that includes the LB7 option.

 

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Catalog is wrong because the Dmax powered one uses a AA (American Axle) 11.5 for sure. Also, they no longer make the corp 10.5 as we know it. The new 10.5 AA makes does not have the straddle mounted pinion of the older 10.5 which changed over around 2001 or so. Also AA now makes the front axle for Dodge HD trucks since 2003. It has a stronger housing and ball studs than the 60 it replaced and uses the same ring and pinion as the GM 9.25 IFS does.

[Jacqson]

I have a G80 unit with 5K on it in my Garage that I would like to sell but it is made for the 9.5" ring gear and the HD uses the 10.5" ring gear.

 

 

Actually the model in the start of this thread uses a rear end with a 11.5 inch ring gear not a 10.5 inch one.

 

<{POST_SNAPBACK}>

 

 

 

 

I have the complete parts catalog in front of me and the exploded diagram of the FF axle for the CK2(HD) series of truck 00-04 and the only ring gear size listed is 10.5" and that includes the LB7 option.

 

<{POST_SNAPBACK}>

 

 

 

 

Catalog is wrong because the Dmax powered one uses a AA (American Axle) 11.5 for sure. Also, they no longer make the corp 10.5 as we know it. The new 10.5 AA makes does not have the straddle mounted pinion of the older 10.5 which changed over around 2001 or so. Also AA now makes the front axle for Dodge HD trucks since 2003. It has a stronger housing and ball studs than the 60 it replaced and uses the same ring and pinion as the GM 9.25 IFS does.

 

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Well ,this could go on all day. I was toying around with replacing my 9.5 SF with a 10.5 FF. I went to a local wrecker which had an 02 Chevy 2500 HD with the LB7 and the M74. We checked the ring gear size and it was a 10.5" ring gear. You may be correct on the later models but the 02 in this truck had a 10.5" ring gear in the axle. So unless GM uses bum info in their parts catalog then I have no reason to think it is wrong.

[snoman]

I have a G80 unit with 5K on it in my Garage that I would like to sell but it is made for the 9.5" ring gear and the HD uses the 10.5" ring gear.

 

 

Actually the model in the start of this thread uses a rear end with a 11.5 inch ring gear not a 10.5 inch one.

 

<{POST_SNAPBACK}>

 

 

 

 

I have the complete parts catalog in front of me and the exploded diagram of the FF axle for the CK2(HD) series of truck 00-04 and the only ring gear size listed is 10.5" and that includes the LB7 option.

 

<{POST_SNAPBACK}>

 

 

 

 

Catalog is wrong because the Dmax powered one uses a AA (American Axle) 11.5 for sure. Also, they no longer make the corp 10.5 as we know it. The new 10.5 AA makes does not have the straddle mounted pinion of the older 10.5 which changed over around 2001 or so. Also AA now makes the front axle for Dodge HD trucks since 2003. It has a stronger housing and ball studs than the 60 it replaced and uses the same ring and pinion as the GM 9.25 IFS does.

 

<{POST_SNAPBACK}>

 

 

 

 

Well ,this could go on all day. I was toying around with replacing my 9.5 SF with a 10.5 FF. I went to a local wrecker which had an 02 Chevy 2500 HD with the LB7 and the M74. We checked the ring gear size and it was a 10.5" ring gear. You may be correct on the later models but the 02 in this truck had a 10.5" ring gear in the axle. So unless GM uses bum info in their parts catalog then I have no reason to think it is wrong.

 

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Sure it can just go and pull the cover off of a rear axle in a Dmax truck (which this guy that started the thread has) and you will find a 11.5 inch ring gear for sure 100%. AA developed the axle for GM to use with Dmax. Below is a link for some Yukon gear sets for that axle

 

GM 11.5

 

Also here is the AAM product link for the 10.5 and 11.5 and if you zoom in on current 10.5 axle you will see that it no longer has the removable pinion cage that the older 10.5 had.

 

AAM 10.5

 

AAM 11.5

 

P.S. the 10.5 and 11.5 both have 14 bolt covers.

[BlackSilver]

That said, just yesterday I was at a dealer browsing window stickers for new trucks and was taken at some of the odd combination of options.  LTs and trucks with DuraMax but without 4wd.

 

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Take a gander at my LT/DuraMax/2WD.

 

It does have a locking rear, but for my kind of usage 4WD is an undesirable option.

 

And before you start waving your snow shovel, I've been driving in Minnesota winters for upwards of 50 years, and have personally found no need for 4WD.

 

If I were a farmer or offroader I'd probably sing a different tune, but I never leave a paved road, so I don't need to pretend "vroom-vroom macho" to impress anyone.

 

But I love my heated leather seats, OnStar, Bose audio system, and XM radio.

[Jester4736w]

03 is nice because of disc brakes, makes things a little easier, although i've had them still stick on occasion. (Not with the truck, other vehicles)

[ctfan]

I thought that it was wierd that my truck didn't have the G80 option either. My truck has both the trailer and plow packages. I think that it should be a standard option with these packages IMO. To bad GM doesn't do like what D$*#ge did with the Powerwagon and add electric lockers.

 

William