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Regearing Axle Ratio from 3.23 to 4.11 or 4.56? Any thoughts???

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2025 Chevy Silverado 1500 LT Trail Boss
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2003 Toyota Tundra SR5
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I am running basically 35s (305/70 18) with a 6" suspension lift. I am considering regearing to a more staunch force axle ratio. Just wondering if anyone has completed this upgrade. If so, what brand for the kit did you go with, i.e., Nitro, Yukon, etc.? Any replies are welcome...I am looking for any info here to help me decide. Thanks!
 
I have not found anyone that makes aftermarket and upgraded ratios for our front diffs yet (AAM or GM front diff is new salisbury style, and not older clamshell style, for the T1 platform and aftermarket hasn't caught up yet). I'm waiting for it too... The only thing available right now is 3.46 or 3.73 out of a current GM half ton truck with those ratios. Going from a 3.23 to 3.73 with a 10 speed trans would probably make a noticeable change but I've got 3.46 and 6 speed so not enough difference for me to make a swap. I've also looked into the Behemoth crawl box, which they say will fit our MP3023 transfer case, but would also need new drive shafts and I'm not sure how it'd cooperate with the electronic sensors and modules controlling the shifts etc... It would be amazing to have that double low ratio for crawling around but I'm not wanting to be the guinea pig for that experiment with my daily driver. :LOL:🤙
 
mrcolieman said:
I have not found anyone that makes aftermarket and upgraded ratios for our front diffs yet (AAM or GM front diff is new salisbury style, and not older clamshell style, for the T1 platform and aftermarket hasn't caught up yet). I'm waiting for it too... The only thing available right now is 3.46 or 3.73 out of a current GM half ton truck with those ratios. Going from a 3.23 to 3.73 with a 10 speed trans would probably make a noticeable change but I've got 3.46 and 6 speed so not enough difference for me to make a swap. I've also looked into the Behemoth crawl box, which they say will fit our MP3023 transfer case, but would also need new drive shafts and I'm not sure how it'd cooperate with the electronic sensors and modules controlling the shifts etc... It would be amazing to have that double low ratio for crawling around but I'm not wanting to be the guinea pig for that experiment with my daily driver. :LOL:🤙
Click to expand...
Thanks for the information! I too do not want to be the guinea pig either.😅So, hopefully we do get some answers here that someone has done this 'cause I would like to change out the axle ratio if it is a possible option.
 
That’s the wrong front gear set for a 19+. That’s for a 14-18 only. Our trucks have an 8” front ring gear. There is a 4.10 ratio available, but who knows who makes it.

First, you’ll need to know if you have the GM SU5 or AAM SU4 front axle. The AAM has the gearing options. Check your rpo codes or look at the cover and compare to this video at 0:14.

This is the 4:10 gear setup. I guess you could call this shop and see if they’ll sell you the carrier snd gear setup.

The rear AAM stuff is the same as a 14-18 9.5 12bolt. They have a carrier split at 3.23/3.42. The old 9.5 14 bolt carriers are the same as the 3.23 and down 9.5 12b. The 9.76 12b gear sets have a larger inner pinion bearing and won’t work in our 9.5 housing. The 9.5 14b gear sets have a different pinion spline count.

I just put a yukon duragrip in my truck this weekend. I’m sticking with 3.23 and 35’s. But my truck has a magnuson blower. A 3.73 or 4.10 and a 35 is going to have a high driveshaft speed at interstate speed and may be too high for the OE aluminum driveshafts critical speed.
 
Here is the 3.73 gear setup for the aam front diff. This is by far the best price.

I have a new rear carrier and pinion shim set and a new 9.5 inner pinion bearing if anyone needs them.

IMG_7705.webp
 
Mike Edwards said:
That’s the wrong front gear set for a 19+. That’s for a 14-18 only. Our trucks have an 8” front ring gear. There is a 4.10 ratio available, but who knows who makes it.

First, you’ll need to know if you have the GM SU5 or AAM SU4 front axle. The AAM has the gearing options. Check your rpo codes or look at the cover and compare to this video at 0:14.

This is the 4:10 gear setup. I guess you could call this shop and see if they’ll sell you the carrier snd gear setup.

The rear AAM stuff is the same as a 14-18 9.5 12bolt. They have a carrier split at 3.23/3.42. The old 9.5 14 bolt carriers are the same as the 3.23 and down 9.5 12b. The 9.76 12b gear sets have a larger inner pinion bearing and won’t work in our 9.5 housing. The 9.5 14b gear sets have a different pinion spline count.

I just put a yukon duragrip in my truck this weekend. I’m sticking with 3.23 and 35’s. But my truck has a magnuson blower. A 3.73 or 4.10 and a 35 is going to have a high driveshaft speed at interstate speed and may be too high for the OE aluminum driveshafts critical speed.
Click to expand...
Thanks Mike! I do have all the RPO codes for my rig. My front axle is AAM SU4. And of course my rear is AAM GU5 3.23 ratio. So, I will have to ask around to see who can do the work for me. My local mechanic I use for major work does not do this complex work. It will take me some time researching to find one who will do the work.
 
Last edited:
Watching…

I am 99% happy with where I have my truck now. Unfortunately, when I purchased it I thought that was the end of my journey and got the 3.23. Now that I am running 35’s on a 2” lift (Cognito Fox 2.0 + Deaver) I am wondering if regearing to 4.10 and a tune is the final piece of the puzzle. That said, as people familiar with my prior posts understand by now, I am somewhat less than capable with a wrench and concerned that opening up the axels for a regearing (and probably upgrade differentials while I am at it) is inviting more trouble than the perceived problem it solves.
 
andrwgrcia said:
Watching…

I am 99% happy with where I have my truck now. Unfortunately, when I purchased it I thought that was the end of my journey and got the 3.23. Now that I am running 35’s on a 2” lift (Cognito Fox 2.0 + Deaver) I am wondering if regearing to 4.10 and a tune is the final piece of the puzzle. That said, as people familiar with my prior posts understand by now, I am somewhat less than capable with a wrench and concerned that opening up the axels for a regearing (and probably upgrade differentials while I am at it) is inviting more trouble than the perceived problem it solves.
Click to expand...
That is true! I think of it as the same whenever a person needs to go in for surgery, complications could arise. Very accurate statement you made regarding "more trouble than the perceived problem it solves". With my setup, I will be attempting to find a reputable mechanic who has experience doing this kind of job. Then, I will make a decision whether to upgrade to a 4.10/4.11 or 4.56 axle gear ratio.
 
Keep me posted. I have done some exploring. Where I live (Hudson Valley, NY) I have found more mechanics who advertise or market transmission and gear work than who actually perform this service on my vehicle on a regular basis and are willing to warrantee their work. I have a great mechanic who does most of my work for me and he is not encouraging me to do this.
 
andrwgrcia said:
Keep me posted. I have done some exploring. Where I live (Hudson Valley, NY) I have found more mechanics who advertise or market transmission and gear work than who actually perform this service on my vehicle on a regular basis and are willing to warrantee their work. I have a great mechanic who does most of my work for me and he is not encouraging me to do this.
Click to expand...
Hmmm...that is some real food for thought! Thanks! I may not even do it, but I simply felt with the larger tires and lift kit, it would be better to go to a higher gear ratio. But, I just need to do some more research on this issue. Thanks!
 
Bring them to TN. I’ve done hundreds of sets of gears. I worked at a mustang shop in the early 2000’s while in college. I bet I did 2-3 sets of gears per week for 2 years. Since then I do stuff for local friends and a few shops.

I’ve done.
Ford: 8.8 and 9”
GM: 8.5 10bolt, 8.875” 12 bolt, 9.5 14 and 12 bolt, whatever the OBS front differential is, 9.5” V2 ctsv rear
Dana: 35, 44 and 60

Gears aren’t rocket science. You need a good press, a bearing splitter, something to measure shims with, a bearing race punch, a dial indicator for backlash and a little ingenuity for stubborn old bearings.

Buy quality gears sets, OEM when available are top. AAM, GM and Dana are available through rock auto. When they don’t have a ratio you want, East Coast Gear Supply or Rons Machining service for Yukon or motive orange label are my second choice. Lower numerical ratio gears (up to 3.73) are less finicky to get a good pattern. 4.10 and up is where it usually gets to be a little more work.

Always start with the factory pinion shim and 90% of the time that’s just right. 99% if you use an oem gear. Go for .005-.008” backlash. Tighter side on our aluminum 9.5 12 bolt since the housing will expand a little more. Since our front diff isn’t a clamshell type, it’s easy to measure backlash and pattern just like the rear.
 
Mike Edwards said:
Bring them to TN. I’ve done hundreds of sets of gears. I worked at a mustang shop in the early 2000’s while in college. I bet I did 2-3 sets of gears per week for 2 years. Since then I do stuff for local friends and a few shops.

I’ve done.
Ford: 8.8 and 9”
GM: 8.5 10bolt, 8.875” 12 bolt, 9.5 14 and 12 bolt, whatever the OBS front differential is, 9.5” V2 ctsv rear
Dana: 35, 44 and 60

Gears aren’t rocket science. You need a good press, a bearing splitter, something to measure shims with, a bearing race punch, a dial indicator for backlash and a little ingenuity for stubborn old bearings.

Buy quality gears sets, OEM when available are top. AAM, GM and Dana are available through rock auto. When they don’t have a ratio you want, East Coast Gear Supply or Rons Machining service for Yukon or motive orange label are my second choice. Lower numerical ratio gears (up to 3.73) are less finicky to get a good pattern. 4.10 and up is where it usually gets to be a little more work.

Always start with the factory pinion shim and 90% of the time that’s just right. 99% if you use an oem gear. Go for .005-.008” backlash. Tighter side on our aluminum 9.5 12 bolt since the housing will expand a little more. Since our front diff isn’t a clamshell type, it’s easy to measure backlash and pattern just like the rear.
Click to expand...
Damn! You definitely know your mechanics! Damn! If I could get away from work long enough, I would definitely think about heading to Tennessee! I have a few relatives living there! Yeah, I only have knowledge for minor work on vehicles. I always had friends help me work on vehicles thru the years. I had a 1972 Nova 383 stroker I have set up for dragging. Had it dialed in the low 12s in the 1/4 mile. Anyhow, working on those motors and such way easier than today's vehicles.
 
Mike Edwards said:
Bring them to TN. I’ve done hundreds of sets of gears. I worked at a mustang shop in the early 2000’s while in college. I bet I did 2-3 sets of gears per week for 2 years. Since then I do stuff for local friends and a few shops.

I’ve done.
Ford: 8.8 and 9”
GM: 8.5 10bolt, 8.875” 12 bolt, 9.5 14 and 12 bolt, whatever the OBS front differential is, 9.5” V2 ctsv rear
Dana: 35, 44 and 60

Gears aren’t rocket science. You need a good press, a bearing splitter, something to measure shims with, a bearing race punch, a dial indicator for backlash and a little ingenuity for stubborn old bearings.

Buy quality gears sets, OEM when available are top. AAM, GM and Dana are available through rock auto. When they don’t have a ratio you want, East Coast Gear Supply or Rons Machining service for Yukon or motive orange label are my second choice. Lower numerical ratio gears (up to 3.73) are less finicky to get a good pattern. 4.10 and up is where it usually gets to be a little more work.

Always start with the factory pinion shim and 90% of the time that’s just right. 99% if you use an oem gear. Go for .005-.008” backlash. Tighter side on our aluminum 9.5 12 bolt since the housing will expand a little more. Since our front diff isn’t a clamshell type, it’s easy to measure backlash and pattern just like the rear.
Click to expand...

Darn you. Every time I think I have put a potential project aside someone comes up and makes me reconsider it.

If I do this I was planning to also swap the G80 for Eaton Truetrac rear differential.
 
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