Offroad Trailblazers and Envoys

New to gearing whats my options?

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

by c bausch » Thu Aug 30, 2012 7:37 am

Hey guy . I want to see what my options were for gearing upgrades at my moment i have stock gear's front and back . Im lifted with 33's but do light roading with the truck and i am un sure on the breaking point. My truck struggles just a little . I want to get some info on options on what i can do for the near future
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by navigator » Thu Aug 30, 2012 8:29 am

you would need to tell us what your "stock" gearing is.
For most it is 3.42 but 3.73 and 4.10 are also options.

For 33s I think most would agree that 3.42 are "OK" for wheeling. The larger issue is when you get out on highway speeds that because of TC lockup they can cause your tranny to overheat.

If you have to hire someone to do your gears (most don't have the tools or skills) it is likely cheaper to find used differentials in the desired gearing and swap them in. In that scenario 3.73 would be fine but 4.10 would be the better choice.
If you are going to swap rears, you might as well get one from a V8 or an Ext. It will be an 8.6 rear end which is stronger and has more aftermarket support than the stock 8.0 found in the I6 SWB models.
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by Cable810 » Thu Aug 30, 2012 9:03 am

That helped me out Chris!! Thanks!! One question. Could we swap our 8.0 to the 8.6?
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by navigator » Thu Aug 30, 2012 9:09 am

I would add that if you are going over 33, most of the hardcore guys would recommend going with 4.56 gears. You can't find those in stock swap parts, you would have to buy the gears and get someone to set them up for you.
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by The Roadie » Thu Aug 30, 2012 9:30 am

navigator wrote:If you are going to swap rears, you might as well get one from a V8 or an Ext. It will be an 8.6 rear end which is stronger and has more aftermarket support than the stock 8.0 found in the I6 SWB models.

Cable810 wrote:That helped me out Chris!! Thanks!! One question. Could we swap our 8.0 to the 8.6?
Chris posted the answer.

Edit: I see the problem .....too many Chris's around here. :work:
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by c bausch » Thu Aug 30, 2012 10:04 am

I drive about 12 miles a day to and from work on the highway so im thinking im going to go with the next size up . Whats the codes in the glove box ? G..?
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by Gordinho80 » Thu Aug 30, 2012 10:10 am

RPO Codes for gear ratios:

GU6 = 3.42
GT4 = 3.73
GT5 = 4.10
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by c bausch » Thu Aug 30, 2012 10:11 am

I also believe i have 3.42 's in my truck

Just looked and confirmed

Ok so I'm prob not going to switch rears just gear's ...? If i have to from to and from work everyday do you think 3.73's would be a safe bet?
Last edited by Gordinho80 on Thu Aug 30, 2012 11:30 am, edited 1 time in total.
Reason: Combined posts
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by fishsticks » Thu Aug 30, 2012 10:47 am

Do it and do it once: 4.10s or 4.56s. You'll be doing it again later otherwise. Gear setups are two things: Time consuming and costly (very costly if you don't do it yourself).
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by HARDTRAILZ » Thu Aug 30, 2012 10:58 am

3.73 is really not enough for 33s. As fish said...go to the 4.+ ratio.
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by Gordinho80 » Thu Aug 30, 2012 10:59 am

Like the others said... do it once. I'm running 33s, and when I regear, I'm going at least 4.10s. I already have the 8.6 rear.
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by HARDTRAILZ » Thu Aug 30, 2012 11:00 am

And dont forget the 9.5 SS rear w stock 4.10s. But only limited slip.
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by c bausch » Thu Aug 30, 2012 11:46 am

So can i put 4.10's in my dif ? Or do i "NEED" a swap to a bigger rear?
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by Gordinho80 » Thu Aug 30, 2012 11:52 am

Find a rear diff from an EXT or V8 with the 4.10s already... then all you'd have to regear is the front.

The 8.6" rear gives you more options for lockers over the 8.0" rear.
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by c bausch » Thu Aug 30, 2012 11:55 am

I have no prob going to 4.10's but wouldn't 4.56's be screaming on the highway?
Last edited by navigator on Thu Aug 30, 2012 1:24 pm, edited 1 time in total.
Reason: updated 4.54 to 4.56 for accuracy
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by HARDTRAILZ » Thu Aug 30, 2012 12:21 pm

c bausch wrote:I have no prob going to 4.10's but wouldn't 4.56's be screaming on the highway?


Not with our overdrive and the large tires.
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by 06MidnightBlue » Thu Aug 30, 2012 12:25 pm

Yukon makes gears for the 8.0. I'm saving up a bit to put 4.10's in my rig.
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by c bausch » Thu Aug 30, 2012 12:37 pm

Ok so i need to find a rear from a ext with 4.10's or 4.56's? What year would have them?
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by Cable810 » Thu Aug 30, 2012 12:38 pm

We swap the rear and have to do the front as well for the gears? Thats what I'm understandin.
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by HARDTRAILZ » Thu Aug 30, 2012 12:46 pm

4.10 is best stock gearing available. 4.56 is solely aftermarket
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