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Changing gear ratio for towing on my 2500

shaffersh1

New Member
Joined
Aug 15, 2013
Messages
4
I am thinking of changing my gear ratio from a 3.73 to 4.10 on my 02 Avalanche 2500 (8.1L). The towing capacity is 10400# with 3.73 and 12000# with 4.10. It pulls OK from GA to FL (all flat), but I don't like the feel in the hills of the Smokies north of here at 16500# GCWR.

Anyone ever done this? I expect to gain a little efficiency when towing (lose some when not). Any pros and cons or advice you can give? Would increasing my tire size effectively do the same thing?

Anyone know what the weak link accounting for the difference between the towing capacities between the ratios (assuming the trans or load on the engine).

Here are my weights from my last trip if that is helpful. https://www.screencast.com/t/3PUjNilnDOR

Curb weight of the truck is 6353#
 
The swap is pretty simple just change the front and rear ring and pinion gears and have it reprogrammed. I never had a 3.73 so I have nothing to compare it to.

I took my big trailer from Lexington to lower Georgia and it handled it pretty well. I had no definite time I had to be there so I did it on a Sunday morning when there was no smoke in the smokies. I also have a few bolt-on mods that make it a little easier to do it.
 
I'd be sure it's a locker. Not that it'll help with towing, but the thing always amazes me. I can pull a 5k lb boat out of the lake in compact sand in 2WD. It gets around well in snow, pulls away from a light like it's just wet concrete. If your doing it, do it all.
 
FYI all 2500 came with g80 lockers
 
MS03 2500 said:
FYI all 2500 came with g80 lockers

No they didn't. Mine was a open diff from the factory. I installed a Yukon grizzly locker after a few years.
 
Really ???

Do you have  3.73 or 4.10
 
I have 3.73's and pull my boat and gear probably around 6000 lbs on hills with no problem. Never towed the max nut I've towed 8-9000 lbs a number of times on some pretty steep and long grades with no problem. I have a tune in it and have to use 91 octane plus cold air intake true duel exhaust all the way with Magnaflow mufflers. You would be surprised with a tune it helps wake up the 8.1L a bit..

You ask about larger tires.. The larger diameter act like taller gears not lower. I have a lift with 34 inch tires, so with the stock ties around 31 inch my overall gear ratio went down numerically. Never calculated it but let's it went from 3.73 to 3.55.

But with 8.1L is has a lot of torque so I've never had a problem, but if if I towed at the max like you and MS03 2500 I would have probably switched to 4.10's.


Try it with a tune and a few bolt ons first and see how you like it, can't hurt..
 
I tow at the max and beyond all the time. With the 373s I just run in 3rd on the highway when towing over 9000 or so. It will run down the interstate with my 40 foot goose neck and 10000 pound 289c cat at 70 no problem.
 
I didn't realize there were that many 2500 built with 3.73, I assumed most of them came with 4.10s.

Another thing to consider is the worst mileage towing on flat land is 8 MPG going up some of those mountains it dropped to 4 but going down them were tricky also. Doing it in 3rd will definitely help.


shaffersh1 said:
I am thinking of changing my gear ratio from a 3.73 to 4.10 on my 02 Avalanche 2500 (8.1L). The towing capacity is 10400# with 3.73 and 12000# with 4.10. It pulls OK from GA to FL (all flat), but I don't like the feel in the hills of the Smokies north of here at 16500# GCWR.

Anyone ever done this? I expect to gain a little efficiency when towing (lose some when not). Any pros and cons or advice you can give? Would increasing my tire size effectively do the same thing?

Anyone know what the weak link accounting for the difference between the towing capacities between the ratios (assuming the trans or load on the engine).

Here are my weights from my last trip if that is helpful. https://www.screencast.com/t/3PUjNilnDOR

Curb weight of the truck is 6353#
What I towed was a 34 foot airstream Weight a bit over 9,300.


What I did was take a run at the mountains if you see the next mountain excellerate just before you crest it get off the gas pedal because going down the other side you wil gain a bunch of speed. The Smokies mountains are no joke.

They are not hills they are mountains and don't depend on the brakes to stop coming down because you will just over heat them so just make sure there is light traffic or semis who know the road.



PS don't put bigger tire on it that will make it worst.
 
4.10' came with the towing package which I didn't get.

I had the 3.73 and barely got by when I had 33" tires.

When I went 35" tires, gearing was so bad I changed to 4.10'.

 
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