Swapping gears in K2500 for better mileage
October 16th, 2015, 10:04 AM
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Swapping gears in K2500 for better mileage
I'm looking at a K2500 4x4 Suburban (07-09 model) optioned the way I want it, and I like the larger gas tank, beefier brakes, etc. I don't have any need for the increased towing capacity as this will be a family hauler, and I'm wondering if I can swap the rear & front end gears or axles to those of what a K1500 burb would have for better freeway mileage? I'm going to verify it, but I believe it comes with 4.10s as it has the 6L. Do I have the option to swap to 3.73, 3.42, or lower while maintaining 4x4 if I pull some junkyard axles and swap parts across? What year Silverado/Suburban parts would I be looking for? I've worked as a mechanic and work on our vehicles so the work doesn't scare me, I just want to know if it's possible or a real PITA.
October 16th, 2015, 10:29 AM
#2
The 6.0 is limited by its engine size and thirst. I don't think you will gain much swapping gears.
Heavier frame and axles will also limit the amount of improvement. I would imagine there would be less than 1-2mpg difference.
if you have 4.10 then yeah I suspect 373 gears will be perfect.
Check you glove box for the axle code.
The absolute best you can do for yourself is keeping your engine in tune, id say E3 plugs, low restriction ehaust and most of all have better driving habits.
I increased my fuel mileage avg from 16.1 to 18.2 just by adjusting how I accelerate and watched my speed.
In my 6 liter denali I could NEVER get better 15-17 on the highway, 11-13 city. No matter how I drove it or the tune. It was all wheel drive too.
My current sub is a 08 3LT 2wd version with a 5.3 flex, and 3:73 gears. They no longer make this gear ratio available for the 1/5 ton 5.3
I get 18.2 avg and 22-25 on the highway. Fully loaded and 75mph it drops to 18.8-22 mpg depending on ambient temps.
Heavier frame and axles will also limit the amount of improvement. I would imagine there would be less than 1-2mpg difference.
if you have 4.10 then yeah I suspect 373 gears will be perfect.
Check you glove box for the axle code.
The absolute best you can do for yourself is keeping your engine in tune, id say E3 plugs, low restriction ehaust and most of all have better driving habits.
I increased my fuel mileage avg from 16.1 to 18.2 just by adjusting how I accelerate and watched my speed.
In my 6 liter denali I could NEVER get better 15-17 on the highway, 11-13 city. No matter how I drove it or the tune. It was all wheel drive too.
My current sub is a 08 3LT 2wd version with a 5.3 flex, and 3:73 gears. They no longer make this gear ratio available for the 1/5 ton 5.3
I get 18.2 avg and 22-25 on the highway. Fully loaded and 75mph it drops to 18.8-22 mpg depending on ambient temps.
October 17th, 2015, 12:59 PM
#3
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I know that my 2011 2500 has the 3.73 rear end and 6spd transmission. With a light foot we avg 14.7-14.9mpg. A light foot is the best option for these beasts.
October 19th, 2015, 6:55 AM
#4
I'm pretty sure the only gear ratio available on the 2500s is/was the 3.73. (ETA - confirmed. In 2008, 5,867 2500s were built and all of them had the 3.73).
You'll likely see a very negligible increase in mileage if you re-gear.
My '08 2500 Burb gets 12-13 around town, and 15-16 on the highway. I am a bit of a leadfoot.
My '09 Denali with the 3.42 gets 13-14 around town, and 16-17 on the highway. And this is probably more attributable to the fact that it's 1000 lbs lighter, as opposed to the slightly taller gear ratio.
As you can see from Scotiapilot's numbers, there's a significant difference in mileage between the half-tons and the 3/4 ton trucks.
As soon as someone starts talking about mileage, a 3/4-ton is probably not the right truck for them. The 2500 is built for one purpose - towing. If you don't tow, the 2500 is complete overkill for any other application.
If you're like me and don't want the 5.3 AFM motor in your truck, then get a Yukon XL Denali. It's still a half-ton, with no AFM in its 6.2.
If you want the beefier brakes, buying a half-ton and doing a brake upgrade would be a hell of a lot cheaper and save you a bunch of money in the long run.
Here's why I own a Suburban 2500:
You'll likely see a very negligible increase in mileage if you re-gear.
My '08 2500 Burb gets 12-13 around town, and 15-16 on the highway. I am a bit of a leadfoot.
My '09 Denali with the 3.42 gets 13-14 around town, and 16-17 on the highway. And this is probably more attributable to the fact that it's 1000 lbs lighter, as opposed to the slightly taller gear ratio.
As you can see from Scotiapilot's numbers, there's a significant difference in mileage between the half-tons and the 3/4 ton trucks.
As soon as someone starts talking about mileage, a 3/4-ton is probably not the right truck for them. The 2500 is built for one purpose - towing. If you don't tow, the 2500 is complete overkill for any other application.
If you're like me and don't want the 5.3 AFM motor in your truck, then get a Yukon XL Denali. It's still a half-ton, with no AFM in its 6.2.
If you want the beefier brakes, buying a half-ton and doing a brake upgrade would be a hell of a lot cheaper and save you a bunch of money in the long run.
Here's why I own a Suburban 2500:
Last edited by intheburbs; October 19th, 2015 at 8:33 AM.
October 21st, 2015, 1:02 PM
#5
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The 2500's are built for towing. Not that it's not a good family hauler. But you're looking at a stiffer ride due to heavy duty leaf springs, and the torsion steering has a different feeling too (compared to rack n pinion). Just seems like you're "hunting Tweety Bird with a cannon." Is there a reason you feel like the standard 1/2 Burb wouldn't handle the job?
This is how we use ours
This is how we use ours
October 21st, 2015, 4:24 PM
#6
The 2500's are built for towing. Not that it's not a good family hauler. But you're looking at a stiffer ride due to heavy duty leaf springs, and the torsion steering has a different feeling too (compared to rack n pinion). Just seems like you're "hunting Tweety Bird with a cannon." Is there a reason you feel like the standard 1/2 Burb wouldn't handle the job?
This is how we use ours
This is how we use ours
The difference in steering is noticeable - even my 17 year-old daughter noticed the difference between our Denali and Suburban.
The ride? Not so much. I'm actually quite happy with the ride of my 2500. On par with the Denali. Maybe they both have a stiff ride and I just don't notice it - the Denali has pretty low-profile tires.