Why I installed 4.10 Gears -

[Heritagedave]

21 minutes ago, SierraHD17 said:

I don't know.  Gm lists the transmission ratios the same so it should not be that.  My tires on my truck tape about 33" tall and spec at 33.9 or so.  There is another guy on another forum with a 4.10 geared 6l80e truck (1/2 ton) and he tachs almost the same as me apparently with a 33" tire which makes zero sense.  You are lower though so that's good haha. I GPS verified mine with 2 GPS units when I set the speedo so I don't think it's wrong. Maybe the overdrive is actually ever so slightly different somehow... or I am crazy.  Hard to say at this point!

 

I threw my combo in my trusty rpm calculator and using a 33" tire and 70 mph with a .66 overdrive I come out at 2145 rpm.  I ran your combo with a 35 inch tire and got 1818 rpm which would make more sense and is the 300 rpm we expect.

Do your calculations with 34" tire I'm curious to see what the difference is within 1 inch.

Thanks for the info -

[Heritagedave]

29 minutes ago, aseibel said:

That's a great write up. Can you also provide your total cost and time it took you? I presume you did the work yourself? How many hours of shop time would it take to have it done?

 

I think this would be a great post to point people to when they ask about changing gears.

I also believe its a much easier job coming from a 3.42. How much more work/$ would be required if going from 3.08?

I wish I was able to say that I did it my self but I dint.

I used a well known shop in my area. It cost me $1600 including parts and Labor [both ends].

I won't think just because you have 3.08 gears would change much.

I will add this info to my original post.

Thank you for the kind words -

[SierraHD17]

38 minutes ago, Heritagedave said:

Do your calculations with 34" tire I'm curious to see what the difference is within 1 inch.

Thanks for the info -

1872 rpm so really 1900 would be what you see or close to it.  So about 54 rpm with an inch change.

[Yondu]

How come 4.10 gears in the back and 4.11 up front?  I know it's no different than having slightly worn tires up front...just curious. 

[Heritagedave]

10 hours ago, Yondu said:

How come 4.10 gears in the back and 4.11 up front?  I know it's no different than having slightly worn tires up front...just curious. 

 Good question, I'm not a 100% sure but this practice has been going on for years.

I always assumed it was to keep the front wheels to have the ability to turn/pull ahead of the rear wells ever so slightly otherwise the rear drive could push the truck straight if the truck weight transfer to the rear of the truck while off roading.

Like I said though I’m not 100% sure.

[pronstar]

 Good question, I'm not a 100% sure but this practice has been going on for years.

I always assumed it was to keep the front wheels to have the ability to turn/pull ahead of the rear wells ever so slightly otherwise the rear drive could push the truck straight if the truck weight transfer to the rear of the truck while off roading.

Like I said though I’m not 100% sure.

Shorter gears in front means the rears are turning faster than the fronts at a given engine rpm...so the situation you’re describing is actually happening on your truck [emoji106]




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[300 Blackout]

2014 5.3 Sierra 4x4 CCSB

I went from 3.42 to 4.56 front and rear. Best performance mod I’ve done and would do it again in a heartbeat. Engine is at 2175rpm at 70mph as measured on my tuner. Gas mileage on the highway with 33.5” tires is in the 20s on cruise control and 87 gas since the truck stays in V4 most of the time. From a stop with TC turned off and a torque brake, I can easily break the rear end loose. In 4hi it launches very quickly and pulls hard. Lots of fun. Very responsive in city driving.

 

I wish they offered factory gears in 4.56. That’s definitely a big selling point for the 4.10s. Can’t go wrong.

[Snowcamo]

2014 5.3 Sierra 4x4 CCSB

I went from 3.42 to 4.56 front and rear. Best performance mod I’ve done and would do it again in a heartbeat. Engine is at 2175rpm at 70mph as measured on my tuner. Gas mileage on the highway with 33.5” tires is in the 20s on cruise control and 87 gas since the truck stays in V4 most of the time. From a stop with TC turned off and a torque brake, I can easily break the rear end loose. In 4hi it launches very quickly and pulls hard. Lots of fun. Very responsive in city driving.

 

I wish they offered factory gears in 4.56. That’s definitely a big selling point for the 4.10s. Can’t go wrong.

I bet gm didn't because v4 would stay active and folks would complain about the sound. I've always been an engine mod guy, but this time around I'll just keep it simple and swap gears. Besides the money to hp feel and mpg gain is better and shouldn't affect engine or trans longevity.

 

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[SierraHD17]

1 hour ago, Snowcamo said:

I bet gm didn't because v4 would stay active and folks would complain about the sound. I've always been an engine mod guy, but this time around I'll just keep it simple and swap gears. Besides the money to hp feel and mpg gain is better and shouldn't affect engine or trans longevity.

 

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Because 3.23s, 3.08s and 3.42's give excellent mileage number in wind tunnels and bogus non real world EPA testing.  

[Snowcamo]

Lmao! So true.

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[Heritagedave]

21 hours ago, pronstar said:

 

 

 

 

Shorter gears in front means the rears are turning faster than the fronts at a given engine rpm...so the situation you’re describing is actually happening on your truck




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Good catch -

You got me thinking so I called my Mechanic and asked him why the different gears between the front and back axles [4.10\4.11].

I was told that our Chevy trucks front and rear axles are made from different company's.

My rear axle is a 9.5" Dana and the front is made by another company which I cant seem to remember their name right now but it's a 8.5" axle, because of this Dana makes a 4.10 gear for their 9.5" axle and the other axle manufacture because it's a 8.5" axle the company makes a 4.10 gear for it.

This being said the bottom line is that it's less than 1% different between the 4.10 and the 4.11 gear and it will not affect the driving ability or cause any issues with the moving parts within the drive line.

Hope this helps -

[300 Blackout]

Good catch -
You got me thinking so I called my Mechanic and asked him why the different gears between the front and back axles [4.10\4.11].
I was told that our Chevy trucks front and rear axles are made from different company's.
My rear axle is a 9.5" Dana and the front is made by another company which I cant seem to remember their name right now but it's a 8.5" axle, because of this Dana makes a 4.10 gear for their 9.5" axle and the other axle manufacture because it's a 8.5" axle the company makes a 4.10 gear for it.
This being said the bottom line is that it's less than 1% different between the 4.10 and the 4.11 gear and it will not affect the driving ability or cause any issues with the moving parts within the drive line.
Hope this helps -

My rear end was made by American Axle Manufacturing. Unless you have some exception to the rule, yours should also be made by AAM. Your mechanic isn’t the first to confuse the rear ends. I was provided incorrect u-joints because they thought I had a Dana rear end. https://s3.amazonaws.com/aamaftermarket/resources/pdf/9.5-GM-12bolt-rear.pdf

[Heritagedave]

48 minutes ago, 300 Blackout said:

My rear end was made by American Axle Manufacturing. Unless you have some exception to the rule, yours should also be made by AAM. Your mechanic isn’t the first to confuse the rear ends. I was provided incorrect u-joints because they thought I had a Dana rear end. https://s3.amazonaws.com/aamaftermarket/resources/pdf/9.5-GM-12bolt-rear.pdf

You are right !!

Thank you for the info !!

http://www.demandaam.com/axle-results?vm=GM&q=9.5"+12+Bolt+-+Rear+Axle