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G80 Rpo Code


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#1 Mossyoakglock

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Posted 28 July 2009 - 12:35 PM

So just looking around on the web and stuff, I've noticed that the meaning of the G80 RPO code might have changed, or is different between vehicles. I've read post in other forums from back in 05/06 that say the G80 is a Limited-slip, but then when I read in posts in 07/08/09, it's a locker. Also noticed that somebody said they had the G80 in a Trans-Am and that it was a limited slip, but in a truck it's a locker.

So, my question is this, even though the G80 code is for the rear axle, is it different between years and between GM vehicles (say between 05 and 08 and between a Silverado/Avalanche vs. Firebird/Transam). What about between an 07 Avalanche and 08 Silverado? If it has the G80, are they both Locking diffs? I know my G80 in my 08 Silverado is locking, but what about my dad's 07 Avalanche w/ G80?

I read where somebody said it's best to get the build sheet for the particular vehicle and see what the G80 description is. So on that question, can somebody here get me a build sheet for my truck and dad's Avalanche?

Sorry for the long post and questions.
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#2 terryk

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Posted 28 July 2009 - 12:48 PM

So just looking around on the web and stuff, I've noticed that the meaning of the G80 RPO code might have changed, or is different between vehicles. I've read post in other forums from back in 05/06 that say the G80 is a Limited-slip, but then when I read in posts in 07/08/09, it's a locker. Also noticed that somebody said they had the G80 in a Trans-Am and that it was a limited slip, but in a truck it's a locker.

So, my question is this, even though the G80 code is for the rear axle, is it different between years and between GM vehicles (say between 05 and 08 and between a Silverado/Avalanche vs. Firebird/Transam). What about between an 07 Avalanche and 08 Silverado? If it has the G80, are they both Locking diffs? I know my G80 in my 08 Silverado is locking, but what about my dad's 07 Avalanche w/ G80?

I read where somebody said it's best to get the build sheet for the particular vehicle and see what the G80 description is. So on that question, can somebody here get me a build sheet for my truck and dad's Avalanche?

Sorry for the long post and questions.


Over the years it's been both limited slip and locker. You can only know in the context of the vehicle.

Edited by terryk, 28 July 2009 - 12:48 PM.


#3 rgrant

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Posted 28 July 2009 - 04:14 PM

So just looking around on the web and stuff, I've noticed that the meaning of the G80 RPO code might have changed, or is different between vehicles. I've read post in other forums from back in 05/06 that say the G80 is a Limited-slip, but then when I read in posts in 07/08/09, it's a locker. Also noticed that somebody said they had the G80 in a Trans-Am and that it was a limited slip, but in a truck it's a locker.

So, my question is this, even though the G80 code is for the rear axle, is it different between years and between GM vehicles (say between 05 and 08 and between a Silverado/Avalanche vs. Firebird/Transam). What about between an 07 Avalanche and 08 Silverado? If it has the G80, are they both Locking diffs? I know my G80 in my 08 Silverado is locking, but what about my dad's 07 Avalanche w/ G80?

I read where somebody said it's best to get the build sheet for the particular vehicle and see what the G80 description is. So on that question, can somebody here get me a build sheet for my truck and dad's Avalanche?

Sorry for the long post and questions.


Over the years it's been both limited slip and locker. You can only know in the context of the vehicle.


In all GM light duty trucks, the G80 code indicates the vehicle is installed with the Eaton G80 locking rear differential. The G80 code in passanger cars indicates LSD. They are 2 completely different systems. The confusion is that the locking G80 in GM trucks uses a clutch type system similar to LSD, except that it fully engages (locks) when more that 100rpm wheel speed difference is detected. All trucks with the G80 code include this locking LSD type differential.

Edited by rgrant, 28 July 2009 - 04:17 PM.


#4 C. Charles Hahn

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Posted 28 July 2009 - 05:57 PM

I guess I always thought G80 was locker, G86 was limited slip.... guess not.
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#5 rgrant

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Posted 28 July 2009 - 06:25 PM

I guess I always thought G80 was locker, G86 was limited slip.... guess not.



The G86 is the standard LSD differential on a non G80 equipped light truck, ever since 2003.

G80 equipped passanger cars were simply designated as LSD equipped vehicles, but do not have the same type of Eaton "Gov-Lock" locking rear like the trucks have. G85 is the GM RPO code for FWD models (COBALT SS), which is a Quiafe LSD.

Edited by rgrant, 28 July 2009 - 06:31 PM.


#6 elcamino

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Posted 28 July 2009 - 06:35 PM

In all GM light duty trucks, the G80 code indicates the vehicle is installed with the Eaton G80 locking rear differential. The G80 code in passanger cars indicates LSD. They are 2 completely different systems. The confusion is that the locking G80 in GM trucks uses a clutch type system similar to LSD, except that it fully engages (locks) when more that 100rpm wheel speed difference is detected. All trucks with the G80 code include this locking LSD type differential.


This is 100% correct.

My 2009 CTS4 has G80 and its a limited slip differential. The codes can mean different things on different vehicles. My truck has a G80 and its a locking differential. The difference in the two is in the names. The limited slip, slips and the locker never does.

from the 2010 CTS ordering guide

G80 Differential, limited slip
1 - Included in (Y42) 18" All-Season Tire Performance Package (Model 6DG69 only)
2 - Included in (Y42) 18" All-Season Tire {Performance Package (Model 6DH69 only). Included and only available in (Y43) 19" Summer Tire Performance Package (Model 6DP69 only with [MX0] 6-speed automatic transmission).

from the 2010 GMC truck ordering guide

G80 Differential, heavy-duty automatic locking rear
1 - Included with (Z82) Trailering Package on Retail Orders only.
2 - Included with (Z82) Trailering Package on Retail Orders only,
(PDU) Power Pack Plus or (NHT) Max Trailering Pack.



watch this video


Edited by elcamino, 28 July 2009 - 06:47 PM.

Mike

#7 2COR517

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Posted 28 July 2009 - 08:26 PM

So is the "Gov Lock" in my 97 an Eaton? Mechanic told me to be easy on mine, pretty easy to break when you're stuck. And I have heard the Eaton is indestructible.

Mine works, though I can't say for sure if one wheel spins a bit first or not.
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#8 Rod R

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Posted 28 July 2009 - 09:33 PM

your 97 GMC G80 will be an Eaton Gov-Lock.... mine works great... In the winter on snowy city streets I can hear it click when it engages and when it releases... your mechanic's advise to take it easy is good for all equipment... but I ahve not heard of any G80 truck axle issues..... once you are going more than about 20-30 mph ??? the Gov-Lock fully disengages.
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#9 DV2000NJ

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Posted 28 July 2009 - 09:35 PM

So is the "Gov Lock" in my 97 an Eaton? Mechanic told me to be easy on mine, pretty easy to break when you're stuck. And I have heard the Eaton is indestructible.

Mine works, though I can't say for sure if one wheel spins a bit first or not.


The G80 holds up well under normal driving conditions, but from what I've heard, they don't handle abuse very well at all.

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#10 rgrant

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Posted 28 July 2009 - 11:12 PM

So is the "Gov Lock" in my 97 an Eaton? Mechanic told me to be easy on mine, pretty easy to break when you're stuck. And I have heard the Eaton is indestructible.

Mine works, though I can't say for sure if one wheel spins a bit first or not.


The G80 holds up well under normal driving conditions, but from what I've heard, they don't handle abuse very well at all.


Correct. G80s turn into "Grenade 80s" when the driver has a heavy right foot and one wheel in mud/water/snow and the other on dry pavement...




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