Gear Swap 3.73 or 4.11 with 8L90 - Towing

6.2Creedmoor · January 5, 2021

I am hoping I can get some input with selecting the best gear ratio regarding my current set up:

2015 Silverado 1500 High Country 6.2L with 8L90

BDS 4" Coil Over Lift

33 X 12.5 R20 Nitto Ridge Grapplers

20X10 -18mm Fuel Contra D616

Wheel and Tire package is 75 lbs. heavier than stock

We are upgrading our travel trailer which will run about 8,000 lbs. gross. We tow maybe a dozen times a year and half of it is over two mountain passes in the Cascades. And we do get plenty of days in the summer that are over 100 degrees. As a result, I will be upgrading to a NHT radiator with a 180 degree thermostat and will be reprogramming the fans. Air bags are being installed with the lift and gear package but I am debating between re-gearing to 3.73 or 4.10 as the 8L90 comes with a 7.0 overall and a 4.56 first gear ratio while the tires are only 1" higher and wheel are 75 lbs. heavier. Thoughts?

m3n00b · January 5, 2021

I'm also curious. Subbed.

Great username OP!

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m3n00b · January 5, 2021

I'm also curious. Subbed.

Great username OP

Sent from my SM-N986U using Tapatalk

CamGTP · January 5, 2021

If you have 3.23's from the factory I'd go with 3.73's.

4.10's would be okay too but that just more aggressive.

garagerog · January 5, 2021

Creed, although I live in SC now, I was born in Wenatchee and spent a lot of time there after my parents retired from the farm to live there, so I'm well familiar with the area. Whatever gear change you go with, you're going to really enjoy the difference, even driving empty. Unless you're just driving north to Chelan, you have significant grades in all the other directions, Stevens Pass to the west, Pine Canyon to the east and that short grade on Trinidad hill to the south. I try and keep up with the local news there by perusing the KPQ and Wenatchee World websites. BTW, welcome to the forum!

6.2Creedmoor · January 5, 2021

2 hours ago, m3n00b said:

I'm also curious. Subbed.

Great username OP

Sent from my SM-N986U using Tapatalk

Thanks man, appreciate that!

39 minutes ago, CamGTP said:

If you have 3.23's from the factory I'd go with 3.73's.

4.10's would be okay too but that just more aggressive.

Yes, I have the 3.23's since the 3.42's were only available in the NHT package which wasn't offered on the HC. I am leaning towards 3.73's and I like the idea that I could get factory AAM gears rather than needing a spacer kit to fit the 4.10's in the 9.76" axle.

Curious to see if anyone has a similar set up and are more than pleased with the 3.73's or wished they would have stepped up to the 4.10's.

6.2Creedmoor · January 5, 2021

30 minutes ago, garagerog said:

Creed, although I live in SC now, I was born in Wenatchee and spent a lot of time there after my parents retired from the farm to live there, so I'm well familiar with the area. Whatever gear change you go with, you're going to really enjoy the difference, even driving empty. Unless you're just driving north to Chelan, you have significant grades in all the other directions, Stevens Pass to the west, Pine Canyon to the east and that short grade on Trinidad hill to the south. I try and keep up with the local news there by perusing the KPQ and Wenatchee World websites. BTW, welcome to the forum!

Garagerog, small world! You know the area well. Most of the time we are headed over Blewett, Snoqualmie, and Stevens pass. Appreciate the input and welcome!

cmysstailights · January 6, 2021

Do it once go 4:10. I have a 2500 and had the 4:10 rpm was around 1700. I know have 4:88 and love it, rpms at 60 are around 2000.

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cmysstailights · January 6, 2021

Do it once go 4:10. I have a 2500 and had the 4:10 rpm was around 1700. I know have 4:88 and love it, rpms at 60 are around 2000.

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CamGTP · January 6, 2021

The 8 speed auto helps his cause with 3.73's.

It would be like going to 4.10's on a 6L80/90e.

lucas287 · January 6, 2021

4.10 has my vote. Best RPM range on the highway!

@ 70 MPH

6th gear = 2900 RPM

7th gear = 2500 RPM

8th gear = 1900 RPM

cmysstailights · January 6, 2021

4.10 has my vote. Best RPM range on the highway!

@ 70 MPH

6th gear = 2900 RPM
7th gear = 2500 RPM
8th gear = 1900 RPM

With that, all the more reason to go lower. Wish i had the new 10spd

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dieselfan1 · January 6, 2021

I say 4.10.
I tow a TT that weighs about 6000 with a 5.3 3.42.
That ratio will probably keep your trans from dropping down too many gears on the grades.

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BCMoto · January 6, 2021

I have 3.23 also but I am leaning towards 4:10s I think its the better choice with the size of the truck and the weight you would carrying.

truckguy82 · January 7, 2021

3.73 for sure if you must change them

8 speed with 4.10’s is absurd, unlikely you will see any performance benefit whatsoever.

and 3.73’s they made oem, 4.10’s you have to go aftermarket

IMO people put way to much importance on this in this day in age.

For nearly a century when you had 2-4 gears, it was indeed very important. Mild importance with 6 speeds. Now with 8 and 10speeds, it doesn’t matter much.

i think people forget the entire point of the rear end ratio is to place the ideal ratio of the number of times the engine spins to the number of times the tires spin. It’s a lot easier to do that when you have 8-10 gear ratio’s to choose from.

Edited January 7, 2021 by truckguy82