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2006 chevy trailblazer_ls
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Discussion Starter #1
From past posts I noticed some have changed to a 4.10 gears I currently have the 3.42 without the locker and with me wanted to change the tire size to a 31" or 33" I did some calculation and shows I need to atleast change my gears to a 3.73 which GM makes as well but is the 4.10 the best option or is there a need at all to change. Also do you put 4.10 in the fron also and can i use the G80 locker for both front and rear......
 

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2006 chevy trailblazer_ls
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From past posts I noticed some have changed to a 4.10 gears I currently have the 3.42 without the locker and with me wanted to change the tire size to a 31" or 33" I did some calculation and shows I need to atleast change my gears to a 3.73 which GM makes as well but is the 4.10 the best option or is there a need at all to change. Also do you put 4.10 in the fron also and can i use the G80 locker for both front and rear......

If you have 4X4, what ever option you choose ratio wise needs to go in BOTH the front and rear Diff.

The G80 Locker is only for the rear. There is no locker for the front.

This mod will run about 1K in parts and prolly another 2K in labor (mostly front labor).
 

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2006 chevy trailblazer_lt
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From past posts I noticed some have changed to a 4.10 gears I currently have the 3.42 without the locker and with me wanted to change the tire size to a 31" or 33" I did some calculation and shows I need to atleast change my gears to a 3.73 which GM makes as well but is the 4.10 the best option or is there a need at all to change. Also do you put 4.10 in the fron also and can i use the G80 locker for both front and rear......
Back in '02, I thought I ordered the 3.73 gears with the locker. Ends up the dufus didn't order the gears so I got the 3.42s. Well at least he got the locker order right. In any case, I didn't pay attention and did not notice until it was too late.

I was also weary that getting 33" tires would make my Trailblazer into a slug. But, the thing that saved me was the PCM tune. With the torque managment "managed", i.e. almost completely removed, it feels like a different vehicle, even with the 33s.

So with 33s and 3.42 gears, I would definitely recommend a PCM tune before anything else. This way you can better judge if you really want to go to the trouble of changing the gears (mainly the front).

As for the locker, this is a much easier upgrade and is needed only for specific situations, mostly offroad of course.

As for me, I have written this up many times before so I will only put it in point form. My goal:
- 4.56 gears (front and rear)
- rear switchable locker (Auburn ected)

AG
 

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2003
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From past posts I noticed some have changed to a 4.10 gears I currently have the 3.42 without the locker and with me wanted to change the tire size to a 31" or 33" I did some calculation and shows I need to atleast change my gears to a 3.73 which GM makes as well but is the 4.10 the best option or is there a need at all to change. Also do you put 4.10 in the fron also and can i use the G80 locker for both front and rear......
If you got the spare cash then the 4.10's are the only way to go. The locker is also one of those no brainer things for off road. (well for the last 35 years I been driving anyway) :x

I can never say enough about a tuned PCM. The TB world changes forever.:thumbsup:
 

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Remember that you'll drop about 3-4mpg (average) and increase engine noise. Great for the strip or towing but would be worse for the road.
 

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I've been driving around since 2004 with 3.42s with 33"s and have been just fine . In fact its still got alot of get up and go .
That said I just placed my order for the PCM tune so it will be even more fun .

James
 

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Remember that you'll drop about 3-4mpg (average) and increase engine noise. Great for the strip or towing but would be worse for the road.
4.10's and 33's actually bring you down to like 3.73's or there abouts.


I've been driving around since 2004 with 3.42s with 33"s and have been just fine . In fact its still got alot of get up and go .
That said I just placed my order for the PCM tune so it will be even more fun .

Me too. I really haven't noticed a huge difference but will probably go to a higher gear by summers end. I am researching tunes these days and want something more than plug and play.
 

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...That said I just placed my order for the PCM tune so it will be even more fun .
Oh, it will be fun to watch you spend money like you just woke up from a long sleep. :p You certainly cost me a bunch without even knowing the effect you were having! :D

Got the Redline hood struts yet? ;)
 

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2002 gmc envoy_slt
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There's quite a few owners looking at possibly upgrading their gears to 4.10 for one reason or another, anybody have connections to possibly setup a group buy of the parts?
 

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Discussion Starter #10
well sounds like I need to just get the lift and tires and see how things go from there
 

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Discussion Starter #11
how is the gas mileage change with the larger tires and lifts and does the pcm help to maintain the mpg with the lift and tires.... I just did the K&N filter but am about to get the exhaust and possible the CAI to help with mpg... so when i do the lift and tires a PCM sound like a must as well...currently i get around 18-19mpg so i would love to stay in that range...
 

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how is the gas mileage change with the larger tires and lifts and does the pcm help to maintain the mpg with the lift and tires....
I lost 3-4 MPG with larger tires with more rolling resistance, and the tune brought none of that back. There seems to be no free lunch. For me it was an acceptable tradeoff. Your mileage may vary, as they say.
 

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group buy gears

the gears are fairly cheap. the gear market is pretty competitive! 175 to 250 per axle about. its the labor that will kill ya. the rear should be pretty straghtforward, the front will be more labor intensive. its takes special tools and some deep knowledge of gear patterns and gear mesh. its a job few guys do really well. you want a gear specialist or dont do it. you could look for a set of axles from a doner truck and swap them your self perhaps? ive seen them on ebay for sale when i was lookin for a g80 4.10 rearend. i would think $2000 would be a rough estimate, parts and labor. i doubt the gear swap itself will effect the mpg much, the bigger tires you put on after the swap will however. the engine will work less to do the same work with a lower gear(higher numerically). you will do a few more rpms, but its easier to push the vehicle down the road. and the trans will downshift alot less often. the power difference will be a nice improvement! i doubt a group buy will happen, and if it did it would amount to much. if you wanna look into gears check drive train specialists, reider racing, randy ring and pinion, and 4wheelparts. good luck
 

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Discussion Starter #14
thanks. As for the labor the guys in our shop where I work can do the work for me for next to nothing it is just me deciding on if I should upgrade or just stay where I am now. But as for labor I am sure thats not an issue the place I work at we rebuild the Military Hummer Differentials and Half shafts. I work in the office though so i do not know first hand how to do it. but thanks guys for the help
 

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... the place I work at we rebuild the Military Hummer Differentials and Half shafts....
Oh, now you have our undivided attention. :yes: :yes: :yes: :yes: :yes:

Actually, we're a bit more interested in anybody with technical data on AAM725 differentials, used by us and the Hummer H3. I know that's not your operation, though. Sigh....
 

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thanks. As for the labor the guys in our shop where I work can do the work for me for next to nothing it is just me deciding on if I should upgrade or just stay where I am now. But as for labor I am sure thats not an issue the place I work at we rebuild the Military Hummer Differentials and Half shafts. I work in the office though so i do not know first hand how to do it. but thanks guys for the help
I would just offer one piece of advice and warning in regards to labor when it comes to the front axle setup. The procedure in the Helms manual for servicing the front differential takes up about 10 pages. This includes getting the front housing detached from the oil pan so that you can work on the insides while its off the vehicle.

To get the housing off the oil pan, the procedure calls for lifting the entire engine 3 inches for clearance when removing. My mechanic made it very clear to me that I should be absolutely ready with all my parts and very sure I want to do this before coming back to him as this is a very lengthy procedure and that it won't be cheap (in terms of labor).

AG
 

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I just upgraded to 4.10's. I'm 2wd, so only "in the rear". I'm loving it thus far (only been a day). I have not noticed any increased "noise" or "whine".
 

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Btw I lost approximately 1.5 mpgs with the gear swap. The performance increase was well worth it however. Night and day difference.
 

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Btw I lost approximately 1.5 mpgs with the gear swap. The performance increase was well worth it however. Night and day difference.
What gears does your truck have? Mine has 3.73s with no locker and I wanna add 4.10s and maybe go up to 31s, do you think the mileage will stay the same? I get about 20-21 on the hwy running 75, that is hand calculated btw
 
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