Help with a decision, Truetrac and gear change (3.73, 3.90, or 4.10)

[jmgak47]

Doing donuts in my new daily 04 GMC Sierra 1500 VHO I toasted the factory G80, boredom has really set in without having a fast toy to play in...

Already decided I on going with the Detroit Truetrac but need help deciding on the gearing. The factory 3.73's work just fine but since I am already going to be having the differential replaced I want to replace the gears too, along with all the bearings. Just the way I do things... once!

This truck will be towing a 5500 lb trailer hauling my drag truck to the track weekly during race season.

So my question is 3.73, 3.90, or 4.10 gears. I am looking for the best balance of benefiting my towing capability, MPG while towing, and MPG while not towing.

Personally leaning to 3.90's but wanted some outside opinions. Thanks!

Jay

[Mf2racer]

Depending on tire size I would just stay with the 3.73s that you already have.

[jmgak47]

They are 275/55/20's

[kerrige]

That's nearly a 32" tire. I would say 4.10s will be best. Plenty of factory vehicles GM come with that ratio so clearly gonna be fine for your daily. You will pick up a little seat of the pants performance and it will generally feel a little lighter especially with the trailers. I am considering going 4.30s on the same tire height. Don't be afraid it's really not that big of a difference.

[62nalide]

3.73s

[Got Torque Diffs]

3.73 to 4.10 Is like night and day.
If your 3.73 is working fine but you want a little more
Umph I would got with the 3.90s it would balance
Out pretty well with a 20" wheel with a good sidewall.
If that's your combo

[kerrige]

3.73 to 4.10 Is like night and day.

What? that doesn't make very much sense. It's a difference of 9%. The reduction in load will be felt, but difference in mileage will be minimal especially on such a tall tire. You will see about 200rpm difference at 75mph and even less than that at lower speeds. City will likely bump up a point or 2 and highway might drop at most 1 or 2 points if at all. The only night and day difference will be the fact that load on the motor will be reduced significantly during acceleration and at speed(required tps% to remain at speed will be reduced). Please explain to me why in his situation a 3.73 or 3.90 would be better.
Rpm @75 mph with 3.73 2056 with 4.10 2260
@55mph 3.73=1508 4.10=1657

[CHEVROLADE]

He will feel a big difference going from 3:73 to 4:10 no doubt about that. You really want to haul ass just do 4:56s

[Frenchy]

What? that doesn't make very much sense. It's a difference of 9%. The reduction in load will be felt, but difference in mileage will be minimal especially on such a tall tire. You will see about 200rpm difference at 75mph and even less than that at lower speeds. City will likely bump up a point or 2 and highway might drop at most 1 or 2 points if at all. The only night and day difference will be the fact that load on the motor will be reduced significantly during acceleration and at speed(required tps% to remain at speed will be reduced). Please explain to me why in his situation a 3.73 or 3.90 would be better.
Rpm @75 mph with 3.73 2056 with 4.10 2260
@55mph 3.73=1508 4.10=1657

When you do the math, no it doesn't make much difference on paper. But that's on paper. Real world, 3.73s to 4.10s is a definite difference.

[jmgak47]

That's nearly a 32" tire. I would say 4.10s will be best. Plenty of factory vehicles GM come with that ratio so clearly gonna be fine for your daily. You will pick up a little seat of the pants performance and it will generally feel a little lighter especially with the trailers. I am considering going 4.30s on the same tire height. Don't be afraid it's really not that big of a difference.

Definitely not scared of going to a lower gearing, just wanted to be sensible about the choice unlike my usual nature which is to go all out and forget gas mileage. My last daily driver was a QC Dodge Ram with 4.56 gears and a 4k stall, surprisingly on the highway the gas mileage was almost identical to stock with 3.92's. City driving on the other hand was a different story...

The majority of my driving is city unless I am towing a trailer to the track on the weekends.

If your 3.73 is working fine but you want a little more

Actually I have never towed a trailer with this truck, so I have no idea how the 3.73's tow lol Just bought it and started a drag truck build also.

City will likely bump up a point or 2 and highway might drop at most 1 or 2 points if at all. The only night and day difference will be the fact that load on the motor will be reduced significantly during acceleration and at speed(required tps% to remain at speed will be reduced).

Sounds to me the 4.10's are better suited for my city driving since the only time I will be on the highway will be towing.

You really want to haul ass just do 4:56s

hah, the ass hauling will be left for the other truck.


Installing another set of 3.73's just seems stupid to me after sleeping on that thought.

Its really looking like 4.10's are the best choice for my application, the 3.90's are a close second. May just flip a coin lol

Do the 3.73's tow pretty good? Honestly IDK... just seemed like to high of a gearing to tow such a heavy trailer.