'15 1500 Gear swap

Lance Bowman · April 26, 2019

I'm considering lifting my 2015 1500 and putting it on 33s. My Jeep friends tell me I should switch to 4.10 gears. Are they correct, or is there a better option? Also wondering if I need wheel spacers to run 33x12.5r18 on a 18x9 Fuel Anza rim?

pewterliftedz · April 26, 2019

19 minutes ago, Lance Bowman said:

I'm considering lifting my 2015 1500 and putting it on 33s. My Jeep friends tell me I should switch to 4.10 gears. Are they correct, or is there a better option? Also wondering if I need wheel spacers to run 33x12.5r18 on a 18x9 Fuel Anza rim?

What engine? What trans? What gear ratio does it have now? Any other mods now?

Lance Bowman · April 26, 2019

5.3L and the 6L80E. Unsure of the gear ratio, most likely the stock 3.08. No mods, its compleatly stock

acinquegrana · April 26, 2019

I'm considering lifting my 2015 1500 and putting it on 33s. My Jeep friends tell me I should switch to 4.10 gears. Are they correct, or is there a better option? Also wondering if I need wheel spacers to run 33x12.5r18 on a 18x9 Fuel Anza rim?

You will be fine. You will read on here most people who go up to 33's have no issues. If anything a high quality tune will be fine. Keep in mind trucks that come with stock 285 45 R22 wheels/tires.. That is a 32.1" tall tire. Keep in mind jeeps come stock with really tiny tires and LOW gearing and there is usually a need to regear. Not required on these trucks. I would say anything 35" and taller you may want to consider it. I am going up tona 285 55 R22 (34.5") and everyone who runs that says its fine.

Sent from my SM-G950U using Tapatalk

Lance Bowman · April 26, 2019

8 minutes ago, acinquegrana said:

You will be fine. You will read on here most people who go up to 33's have no issues. If anything a high quality tune will be fine. Keep in mind trucks that come with stock 285 45 R22 wheels/tires.. That is a 32.1" tall tire. Keep in mind jeeps come stock with really tiny tires and LOW gearing and there is usually a need to regear. Not required on these trucks. I would say anything 35" and taller you may want to consider it. I am going up tona 285 55 R22 (34.5") and everyone who runs that says its fine.

Sent from my SM-G950U using Tapatalk

Thanks! It has 265/75/r17s on it now, which are 31" tall, so its not that big of a jump in tire size. Who makes a quality tune for these trucks?

acinquegrana · April 26, 2019

Thanks! It has 265/75/r17s on it now, which are 31" tall, so its not that big of a jump in tire size. Who makes a quality tune for these trucks?

I hear good things about diablo. You can input your tire size, upgrade to 93 fuel and do so many other things. You can even send it out to a company called diablew and he makes custom tunes. There are many other options thats just the first thay came to mind.

Sent from my SM-G950U using Tapatalk

pewterliftedz · April 26, 2019

The 3.08 ratio sucks with any tire larger that stock, but it's pricey to do a gear swap (especially if you're 4wd). If you're 2wd I would highly consider jumping up to a 3.73 gear ratio with a 33x12.5 tire, your truck will be pretty gutless and hunt for gears under light acceleration with the 3.08s.

You can get a tune or mods to gain HP, but you will always be at a mechanical disadvantage with such a numerically low gear ratio. 3.08s should have never been offered in a full size truck IMO, 3.42 should be the minimum.

Logan Lanfear · April 26, 2019

1 hour ago, pewterliftedz said:

The 3.08 ratio sucks with any tire larger that stock, but it's pricey to do a gear swap (especially if you're 4wd). If you're 2wd I would highly consider jumping up to a 3.73 gear ratio with a 33x12.5 tire, your truck will be pretty gutless and hunt for gears under light acceleration with the 3.08s.

You can get a tune or mods to gain HP, but you will always be at a mechanical disadvantage with such a numerically low gear ratio. 3.08s should have never been offered in a full size truck IMO, 3.42 should be the minimum.

We could go back to the 80's. My 1982 GMC K2500 (6.2 Diesel and TH-400) had 2.56 gears. It would cruise very nicely at 60-65.

These new transmissions really make up for a low rear gear. 3 speeds vs 6,8 or even 10 is no comparison.

Snowcamo · April 26, 2019

20 minutes ago, Logan Lanfear said:

We could go back to the 80's. My 1982 GMC K2500 (6.2 Diesel and TH-400) had 2.56 gears. It would cruise very nicely at 60-65.

These new transmissions really make up for a low rear gear. 3 speeds vs 6,8 or even 10 is no comparison.

While this is true you still cant account for the extra centrifugal mass added by the rims and tires with an extra gear or three in the trans. Sure youd be fine but leta face it these trucks are dogs in comparison to even the late 80s and 90s with 3.08 gears. And diesel engines really dont like high rpms down low is where they thrive and come to life over a gasser. Adding lower gears makes it easier on the trans and can have a positive or negative effect on mpgs that most are concerned with.

pewterliftedz · April 26, 2019

59 minutes ago, Logan Lanfear said:

We could go back to the 80's. My 1982 GMC K2500 (6.2 Diesel and TH-400) had 2.56 gears. It would cruise very nicely at 60-65.

These new transmissions really make up for a low rear gear. 3 speeds vs 6,8 or even 10 is no comparison.

I've had various truck with different tran/rear gear combos from 4l65e with 4.56s to 8L90 with 3.23s, and a bunch in between. I will say that that lack of torque of 5.3 combined with big tires and 3.08s will suck in town, highway will be fine cruising.

Jacoby · April 26, 2019

3.08 sucks even with stock tire. If you’re gonna lift it and put bigger tires on it then regearing is a huge benefit. Up to you if you wanna pay for it

acinquegrana · April 26, 2019

I should have noted too that I have a z71 with 3.42 gears... So definitely not as bad as the 3.08.

Sent from my SM-G950U using Tapatalk

Lance Bowman · April 28, 2019

4 hours ago, pewterliftedz said:

The 3.08 ratio sucks with any tire larger that stock, but it's pricey to do a gear swap (especially if you're 4wd). If you're 2wd I would highly consider jumping up to a 3.73 gear ratio with a 33x12.5 tire, your truck will be pretty gutless and hunt for gears under light acceleration with the 3.08s.

You can get a tune or mods to gain HP, but you will always be at a mechanical disadvantage with such a numerically low gear ratio. 3.08s should have never been offered in a full size truck IMO, 3.42 should be the minimum.

My truck is 4wd. Would I be able to swap 3.73s in without changing anything else (differential, axle housings)?

pewterliftedz · April 29, 2019

43 minutes ago, Lance Bowman said:

My truck is 4wd. Would I be able to swap 3.73s in without changing anything else (differential, axle housings)?

No, you will have to swap carriers.

Darksky · May 3, 2019

The carrier is part of the gear assembly. It’s not any big deal. 3.73 is a good choice. You should go and talk to a shop and have them run the actual numbers, so that you can see exactly what rpms your truck will be at at each speed. 4.11 is not unheard of at that size, but is a lot of gear for a daily driver, that has been at 3.08 OEM. Look at the numbers and be honest with yourself as far as your goals. If you’re driving a 6.2 liter truck (you’re not) with the 9.76 inch rear end, then 3.73 is the largest you can go without swapping out the internals completely.

Even at only 3.73, you’re going to be amazed at the difference in your trucks performance. It will be very pleasing. Your mileage may actually improve, it will quit hunting for gears and you will get actual use out of the higher gears in the transmission without speeding on the highway...