Regearing?

[Trail X]

I had no issue with my abs.

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That's right.

Momentary memory lapse. 2006+ have no abs issue because of the 4th abs, vs the 3ch on 2005- models. Wooops.

[v7guy]

I had no issue with my abs.

That's cause you don't have any, you're round like me.

[HARDTRAILZ]

Bazinga!

[MKETrailblazer]

I already have a speedo error but I used my gps to figure out the error. But since I live in Wisconsin its kind of hilly it all depends on where you go. I figure I would get 4.10s and the pcmforless tune and that would be sufficient

[MKETrailblazer]

And I have looked over that chart just not sure how to quite to read it

[Shdwdrgn]

Just an FYI -- none of the off-the-shelf tunes will correct your speedo in the 2002-2005 models. However that information CAN be copied over from another model with the gears you are looking for, using HPTuners (and probably others, if anyone wants to experiment). GM has been mostly unwilling to help us make these changes, but we're getting it figured out ourselves. The way I changed my programming was to provide a VIN number to my dealer from a 2004 TB that came with the GT5 gears. They programmed my PCM with that info, then I used HPTuners to rewrite the VIN back to my original number and then copied over all of my tuning changes. It was a bit of a pain, but my gauges are right on the mark now.

The gearing chart gives you a comparison of engine RPM across various gears and tires sizes so you can see the net effects of the changes you are considering. For example, I compared 3.42s with stock tires against 4.10s with 30.5" tires, and found at 65mph there was only a difference of 300rpm in engine speed. I originally believed that changing from 3.42s to 4.10s would be too dramatic of a difference for my daily needs, but after seeing the actual numbers I realized the difference was nowhere near as great as I had feared (and in practice, the 4.10s turned out to be absolutely perfect for my daily drive and occasional highway usage). The chart can show you where your RPM ranges might be with a target set of gears and tires, which you can compare against how your own vehicle handles are various RPMs.

[Cable810]

Look at complete Offroad for Ring and pinion. They have some really good prices!

[MKETrailblazer]

It doesn't bother be much that my speedo is off (another excuse to get a speeding ticket lowered ) but for the gears I was thinking that 4.10 would be about right and thank you for the explanation of the chart! Helped out a lot.

[COUNTRYTBLS]

So I have read through this a couple of times and I want to make sure I am 100% understanding everyone correctly.

Front end:
You can rebuild the front diff with 4.10 without having to buy a completely different diff and make sure to use the 8.6" instead of the 8.0"?

Rear End:
Need to get a whole new/used different rear diff with 4.10 because it's cheaper than a rebuild and easy to change?

I want to go bigger and badder so I want to run 35's. I already have 32's and a 2.5" kit from MarkMC, 1.5" wheel spacers, external trans cooler and 3.42. I want to do the 3" Suspension and the 3" Body with Z71 shocks in back, Z71 springs in front and bilstein struts in the front. There are a lot of hills around me and I use the freeway frequently, driving 70-75mph most of the time anyhow. The slowest I go is 45mph. I also tow a lot of things. So would it be better for me to swap to 4.56 to run 35's with all the hills, high mph and towing or is the 4.10 going to be fine?


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[maricard]

what is a z71 front spring?

[Shdwdrgn]

You're getting close... The front diff is compatible between all years and models. The 4.10 was a stock option, meaning that it will fit in any of the stock diffs. There are no sizes for the front diff.

The BACK end is where you want to get the 8.6", and this is the reason you want to just swap out the entire axle. The larger housing has more strength without losing clearance, and provides room for larger gears. This is also available with stock 4.10 gears. However the rear axle had changes between years... Since you have a 2006, you will need to get a 2006 or newer rear axle so that it has the required ABS sensors. Other than the year, it doesn't matter which model you pull from.

I can't give you an experienced opinion to help decide between 4.10s or 4.56s, but considering you won't be using this for full-time offroad use, and in fact will spend a lot of time on the highway, I would lean towards the 4.10s. With the stock front diff and the 8.6" rear axle, you will have room to install the 4.56's later on if your driving habits change.

[HARDTRAILZ]

If I was not buying complete setup diffs...I would go 4.56 for sure if just swapping gears

[COUNTRYTBLS]

what is a z71 front spring?

Idk. Guy at CARQUEST said that. I'm no mechanic so I didn't know.


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[COUNTRYTBLS]

You're getting close... The front diff is compatible between all years and models. The 4.10 was a stock option, meaning that it will fit in any of the stock diffs. There are no sizes for the front diff.

The BACK end is where you want to get the 8.6", and this is the reason you want to just swap out the entire axle. The larger housing has more strength without losing clearance, and provides room for larger gears. This is also available with stock 4.10 gears. However the rear axle had changes between years... Since you have a 2006, you will need to get a 2006 or newer rear axle so that it has the required ABS sensors. Other than the year, it doesn't matter which model you pull from.

I can't give you an experienced opinion to help decide between 4.10s or 4.56s, but considering you won't be using this for full-time offroad use, and in fact will spend a lot of time on the highway, I would lean towards the 4.10s. With the stock front diff and the 8.6" rear axle, you will have room to install the 4.56's later on if your driving habits change.

I actual do a lot of off-roading


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[v7guy]

I would go with 4.56s as well. I've driven 4.56s and 4.10s on 33s, I prefer the 4.56s and the hit in mpg isn't that much at all.

With 35s I'd def go with 4.56s, although it'll be more expensive, you'll be happier with the outcome.


Shdwdrgn covered all your other misconceptions. If you go 4.56s just get the cheapest 3.42 8.6 you can find. cause it's gonna need rebuilt anyways.

[Eredin]

I would go with 4.56s as well. I've driven 4.56s and 4.10s on 33s, I prefer the 4.56s and the hit in mpg isn't that much at all.

With 35s I'd def go with 4.56s, although it'll be more expensive, you'll be happier with the outcome.


Shdwdrgn covered all your other misconceptions. If you go 4.56s just get the cheapest 3.42 8.6 you can find. cause it's gonna need rebuilt anyways.

Agreed 100%. I'd opt for 4.56 in a heartbeat if I went anything over 33s and the fuel mileage will be better than you think. 32s and 4.10 with gear, I got 18 highway on 87 octane.

[Shdwdrgn]

That's why my opinion isn't experienced. Listen to those guys, they know what they're talking about. I run 4.10s with 30.6" tires, and it's absolutely fantastic, but I've never run larger tires.

You can also check the gear ratio calculator and use it for comparison at different speeds, gears, and tire sizes. Compare your target tires and gear to the RPM range of your current setup, and just keep in mind that higher RPM will give you better torque but lower fuel mileage. Then you can find the trade-off that works for you.

[HARDTRAILZ]

I bet I would get better MPG with 4.56 than 4.10s with the 35s.

[Shdwdrgn]

I bet if you were running 35's you wouldn't really care about your MPG

[HARDTRAILZ]

I run 35s and REALLY care about my MPG.