Offroad Trailblazers and Envoys

Lockers/axels/ratios Point me in the right direction?

G80, GU6, GT4, GT5, WTF? This section is for gearing and driveline stuff.

by snowmirage » Wed Jul 13, 2011 11:12 pm

I do apologize as I'm sure this must have been detailed some place here or on trailvoy but I am having a heck of a time finding it dispite my weeks or searching. :?

Firstly how can I find out what my trucks gear ratio is? I assume its in the VIN codes but in all my reading I havent heard it mentioned yet.

As I have the Short Wheel base model I assume I most likely have the 8" rear end. Or do I 100% have the 8" (2003 Trailblazer LTZ 4x4 I6)? I get the impression the 8.6 was only available with the V8's?

Many people seem to throw terminology around willy nilly interchanging "limited slip" and "locker". To my understanding (and I'm pretty sure I am right) "limited slip" allows one wheel to spin X amount faster than the other. While a "locker" locks the wheels together and they must spin at the same speed, and when most of us are referring to a locker they mean a mechanically engaged locker, the unit senses when the wheels start to spin and locks them together. I am not 100% clear on which of these were offered as factory options as I have heard posts mentioning both on the other site.

I have heard mention of the G80 being available as a factory option for the 8" is this a "locker" or a limited slip diff?

From what I understand the long wheel base models (EXT and such) came with an 8.6" rear end. Did ALL the EXT models come with this axel? Certain years? What locker / limited slip options were offered from the factory with that axle? And how can they be identified?

I was considering going and finding a junked Trailvoy that came with the factory locker / limited slip that I wish I had. I figure that the 8.6" from the EXT if readily available shouldn't be that much more than the 8" and would be that much stronger.

Lastly how can I tell if a vehicle has/ or had the 8" or the 8.6" and if its axle has the factory locker / limited slip option, by VIN I am guessing ? Any indication just by looking at the axle?
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by Diacom » Wed Jul 13, 2011 11:44 pm

This will answer some of those questions

http://forums.offroadtb.com/viewtopic.php?f=27&t=1351

As for how to find the gear ratio... it's in the glove box, you'll need to keep searching to find out what codes to look for.

Hint: G80 is one of the codes.

Your information is basically correct on the limited slip vs locker, again refer to the linked post. No locker was factory, just the option for the limited slip.

V8 and extd have the 8.6, some with, most with out the G80. Use http://www.car-part.com/ to source yours.

Rest can be found via more reading :coffee2:
Last edited by Diacom on Wed Jul 13, 2011 11:48 pm, edited 1 time in total.
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by fishsticks » Wed Jul 13, 2011 11:46 pm

snowmirage wrote:I do apologize as I'm sure this must have been detailed some place here or on trailvoy but I am having a heck of a time finding it dispite my weeks or searching. :?

Firstly how can I find out what my trucks gear ratio is? I assume its in the VIN codes but in all my reading I havent heard it mentioned yet.

As I have the Short Wheel base model I assume I most likely have the 8" rear end. Or do I 100% have the 8" (2003 Trailblazer LTZ 4x4 I6)? I get the impression the 8.6 was only available with the V8's?

Many people seem to throw terminology around willy nilly interchanging "limited slip" and "locker". To my understanding (and I'm pretty sure I am right) "limited slip" allows one wheel to spin X amount faster than the other. While a "locker" locks the wheels together and they must spin at the same speed, and when most of us are referring to a locker they mean a mechanically engaged locker, the unit senses when the wheels start to spin and locks them together. I am not 100% clear on which of these were offered as factory options as I have heard posts mentioning both on the other site.

I have heard mention of the G80 being available as a factory option for the 8" is this a "locker" or a limited slip diff?

From what I understand the long wheel base models (EXT and such) came with an 8.6" rear end. Did ALL the EXT models come with this axel? Certain years? What locker / limited slip options were offered from the factory with that axle? And how can they be identified?

I was considering going and finding a junked Trailvoy that came with the factory locker / limited slip that I wish I had. I figure that the 8.6" from the EXT if readily available shouldn't be that much more than the 8" and would be that much stronger.

Lastly how can I tell if a vehicle has/ or had the 8" or the 8.6" and if its axle has the factory locker / limited slip option, by VIN I am guessing ? Any indication just by looking at the axle?



***Flexes fingers***


RPO Codes for gear ratios:

GU6 = 3.42
GT4 = 3.73
GT5 = 4.10


With a short wheel base TrailVoy, you will be guaranteed to have an 8" rear axle.

All EXT and V8 Trailvoys have the 8.6" rear end, with the exceptiong Of Trailblazer SS's which have a 9.5". Ther are TWO versions of the 8.6", as they changed the ABS sensor position in 2006. Being a 2003 model year you can use a rear axle from any EXT/V8. 06 and up can only use 06 and up if they want to keep ABS.

The G80 is kind of a cross between a limited slip and a locker. A locker locks both wheels together at all times except when in a turn. The G80 allows some wheel slip before engaging clutches (much like a limited slip) and locking he rear wheels together.

There are several reasons IMO to NOT want the G80. They are detailed elsewhere. If you are going to go through the time and energy to get an 8.6" axle for the added strength, skip the G80 and get a real locker. There are several made for the 8.6".
11 Silverado LTZ - 6.2L/6l80, 2/3 drop, self tuned
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by Trail X » Thu Jul 14, 2011 8:58 am

The G80 is a locker. It's referred to as an auto locker. There are essentially 3 versions of lockers. Auto lockers (activated by a governor that senses wheel slip), all-time lockers (like a lock-right), and selectable lockers (air lockers or electronic lockers operated manually by a switch).

Limited slips do not transfer torque if one wheel has no traction. Limited slip diffs are for track cars. For them, it basically means you're less likely to light up a tire.

For reference, gear ratio RPOs could have been found in our article section: http://www.offroadtb.com/articles/tech- ... icle-specs
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by snowmirage » Thu Jul 14, 2011 11:37 am

Thanks for the all the info that cleared up a lot.

Despite the issues with the factory optioned G80 it still sounds like its a far better option than the open diff I have now right?

I suspect my best bet is to swap out my 8" for a 8.6" with a "locker" from the factory. Then upgrade that down the road.
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by bartonmd » Thu Jul 14, 2011 11:44 am

IMO, if you're going to up grade axles, the cheapest thing to do is get one with the G80 already in it... However, you can get an open 8.6 for cheaper, and can put a lock-right lunchbox locker in it for about $360, in an afternoon... Lunchbox lockers just replace the spider gears in your stock (non-G80) carrier, so no having to set lash or anything, like if you replaced the carrier (which you would have to do if you got one with a G80, then wanted to go to a "real" locker later)

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by Flying Monkey » Thu Jul 14, 2011 1:07 pm

This is also on my "to do" list since I dont have a G80. So to make sure I understand correctly it would be better in long run to pick up a 8.6 and put the Lunchbox Locker in it?
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by Trail X » Thu Jul 14, 2011 1:14 pm

Flying Monkey wrote:This is also on my "to do" list since I dont have a G80. So to make sure I understand correctly it would be better in long run to pick up a 8.6 and put the Lunchbox Locker in it?


Lunchbox is not necessarily better, just cheaper to install.

I vote for getting the 8.6 w/ G80... then if you don't like it, go get a selectable. The issue is only that a G80 housing is possibly not strong enough for a lunchbox locker.
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by Flying Monkey » Thu Jul 14, 2011 1:17 pm

JamesDowning wrote:
Flying Monkey wrote:This is also on my "to do" list since I dont have a G80. So to make sure I understand correctly it would be better in long run to pick up a 8.6 and put the Lunchbox Locker in it?


Lunchbox is not necessarily better, just cheaper to install.

I vote for getting the 8.6 w/ G80... then if you don't like it, go get a selectable. The issue is only that a G80 housing is possibly not strong enough for a lunchbox locker.


my original plan was to start hitting junk yards and such to try to find just a better geared G80. Want at least a 3.73. I think the 3.73 would be better on 33's then my 3.42 (non-G80). And if I go to 35's later with BL ill definatly need something higher then then 3.42.
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by Trail X » Thu Jul 14, 2011 1:18 pm

Caution, regearing in the rear requires regearing in the front if you wish to use 4WD.
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by bartonmd » Thu Jul 14, 2011 1:19 pm

JamesDowning wrote:
Flying Monkey wrote:This is also on my "to do" list since I dont have a G80. So to make sure I understand correctly it would be better in long run to pick up a 8.6 and put the Lunchbox Locker in it?


Lunchbox is not necessarily better, just cheaper to install.

I vote for getting the 8.6 w/ G80... then if you don't like it, go get a selectable. The issue is only that a G80 housing is possibly not strong enough for a lunchbox locker.


I think the issue is that the G80 housing isn't the same on the inside as the open housing, so the lunchbox won't fit... and yes, it's not as strong as the open carrier housing...

Yes, the real way to do it is to get whatever you can find, and put an ARB in it, but the cheapest way to get a real locker is to go lunchbox with an open carrier...

Mike

Flying Monkey wrote:my original plan was to start hitting junk yards and such to try to find just a better geared G80. Want at least a 3.73. I think the 3.73 would be better on 33's then my 3.42 (non-G80). And if I go to 35's later with BL ill definatly need something higher then then 3.42.


You know you'll also have to change out your front diff, right?

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by snowmirage » Thu Jul 14, 2011 1:21 pm

Flying Monkey wrote:my original plan was to start hitting junk yards and such to try to find just a better geared G80. Want at least a 3.73. I think the 3.73 would be better on 33's then my 3.42 (non-G80). And if I go to 35's later with BL ill definatly need something higher then then 3.42.



If your running 4x4 you would have to change the gearing in the front diff as well which I suspect is no easy task. Unless I am very mistaken.....



*You both beat me to it ! ;o)
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by Flying Monkey » Thu Jul 14, 2011 1:28 pm

bartonmd wrote:
Flying Monkey wrote:my original plan was to start hitting junk yards and such to try to find just a better geared G80. Want at least a 3.73. I think the 3.73 would be better on 33's then my 3.42 (non-G80). And if I go to 35's later with BL ill definatly need something higher then then 3.42.


You know you'll also have to change out your front diff, right?

Mike



I didnt think about that. But I can see that 2 different gear ratios could cause problems. What are you guys that switch to a different rear doing to support the larger tire size?

Found a 3.73 G80 for $249 plus freight.
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by djthumper » Thu Jul 14, 2011 1:33 pm

Flying Monkey wrote:my original plan was to start hitting junk yards and such to try to find just a better geared G80. Want at least a 3.73. I think the 3.73 would be better on 33's then my 3.42 (non-G80). And if I go to 35's later with BL ill definatly need something higher then then 3.42.



If you are looking at re-gearing anyhow I would only want to do the front and rear once. I would just get an 8.6 rear end and start setting that up with 4.56 gears. They will give you plenty of torque with the 33's and if you decide to go to the 35's later will still provide you with plenty of torque take a look at this gear ratio guide to see what I am talking about. It isn't that our engines lack power, it actually gives us a slight advantage to make up a slight loss of torque. But we can have all of power in the world and the truck won't move without torque.
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by Flying Monkey » Thu Jul 14, 2011 1:36 pm

Quick search on ebay for front diffs was discouraging. 3.42 $525, 4.10 $825 :wallbash:
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by Trail X » Thu Jul 14, 2011 1:41 pm

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by Flying Monkey » Thu Jul 14, 2011 1:52 pm

Thanks. I actually found a few some what locally. Not gonna be a cheap upgrade but I good 1 none the less
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by snowmirage » Thu Jul 14, 2011 1:58 pm

Anyone know come across some pictures of the 8.6 axle with the G80? Or maybe even just a exploded tech diagram. I don't think I have seen anyone on the forums who's done it post up pictures ect yet. I'll keep searching.
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by snowmirage » Thu Jul 14, 2011 1:59 pm

Turns out typing correctly (trailblazer 8.6 G80 and NOT G89) helps on google image search... lol
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by snowmirage » Thu Jul 14, 2011 2:04 pm

For those that may be searching.... not sure how I never came across this before (must have been keyword failure on my part :wallbash: )

http://forums.trailvoy.com/showthread.php?t=56696#


Now I'll at least know what I am looking for :o)

Note to self axle should NOT! look like the 9th picture in that post haha, man that sucks
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