Towing 3.73 or 4.10

[DOGMAN]

I'm going to be towing a 4,000 lb travel trailer(AIRSTREAM), The 03 crew Cab  I was looking at  has the tow pkg &4.10's. One of the salesman tells me to go with the 3.73's because the 4.10s will waste gas & the 3.73's are sufficent & the truck has a tow mode anyway. Opinions please? I  don't want a truck that gets 8-10mpg. If i wanted that I would buy a Superduty(FORD).

[Colorado Kid]

You want to give us a hint about the rest of the powertrain?

 

Since you're debating 3.73 vs 4.10 and it's a crew cab I think you're in one of two situations:

 

1) Truck is 1500HD, so it has a 6.0L and 4L80-E trans.

In this case I thingk the 4.10's will be nicer to live with.  It'll tow your current load either way, but it'll do it easier with the 4.10's.  The only time this will get 8-10 MPG is when towing your load very fast.  Expect about 14-15 highway when not towing.

 

2) Truck is 2500HD with 8.1L and Allison.  (The 6.0 only comes with 4.10 gears in 2500HDs, and the D-max only comes with 3.73).

In this case, unless you're planning a major trailer upgrade the 3.73s will be adequate.  Actually either ratio would be pretty nice with the 8.1L...I probably wouldn't turn down a truck based on the difference.  8.1s see around 12-13 MPG highway...the gearing might make 1 MPG difference without a load, and the 4.10s might actually return marginally better MPG than the 3.73 towing.

[BlackSilver]

I agree with the salesman.  At 4,000# your trailer is an easy load for 3.73 gears.

[timk49]

All the others said is true but if you are thinking about getting taller tires(285's ) they will reduce your gear . I figure that my 4.10 gear is a 3.80 with  the new BFG's. A 3.73 would drop to 3.40 educated (guess). that may be a problem towing. I certainly feel better knowing that my 4.10 s are working hard for me when Im towing my rig.

[maggot]

I have some good input for you .  I have the 3.73s in mine 1500HD 364 motor.   My old rig weighed around 5000 and was a tag along , lower profile less wind. It did great.  Now I yank around 8000-8500# of 5th wheel . It still pulls good for what it is, but if I did it again 4.10s. I would be much more happier with the 4.10s with my current rig.

 

By the way I do not get 8 pulling, somewhere between 4 and 5 with the 5th wheel, the old tag along I seen 11Mpg on the flats  and around 9 in the hills. Big difference 4000# and that higher rig makes.

[John R]

All the others said is true but if you are thinking about getting taller tires(285's ) they will reduce your gear . I figure that my 4.10 gear is a 3.80 with  the new BFG's. A 3.73 would drop to 3.40 educated (guess). that may be a problem towing. I certainly feel better knowing that my 4.10 s are working hard for me when Im towing my rig.

I'm wondering how different size tires can change

your gear ratio in the rear end?

Doesn't make sense to me.

No matter what size your tires are you still have the

same gear ratio that you started with.

[Shaners]

I'm wondering how different size tires can change

your gear ratio in the rear end?

Doesn't make sense to me.

No matter what size your tires are you still have the

same gear ratio that you started with.

It theoretically changes your final gear ratio when change to a larger tire.  A larger tire makes fewer revolutions per mile, and that would reduce your final rear gears from say... 4.10 to 3.80 .  Yes you would still have the 4.10's in the rear end, but the larger tires would make the power ratio feel like 3.80's.

 

Most guys that lift their trucks and put big tires on them, will usually swap gears to something like 4.56's, so that they don't have too much powertrain loss...

['02 HD]

I'm wondering how different size tires can change

your gear ratio in the rear end?

Doesn't make sense to me.

No matter what size your tires are you still have the

same gear ratio that you started with.

It theoretically changes your final gear ratio when change to a larger tire.  A larger tire makes fewer revolutions per mile, and that would reduce your final rear gears from say... 4.10 to 3.80 .  Yes you would still have the 4.10's in the rear end, but the larger tires would make the power ratio feel like 3.80's.

 

Most guys that lift their trucks and put big tires on them, will usually swap gears to something like 4.56's, so that they don't have too much powertrain loss...

Shaners,  I run LT28575R16's with a 4.10 / 6.0L combination.  What relative ratio does that give me on the ground?  thanks.

[Shotgun]

I would go with the 3:73 gears unless you plan on going with larger tires then I would go with the 4:10 's :thumb:

[Shaners]

Shaners,  I run LT28575R16's with a 4.10 / 6.0L combination.  What relative ratio does that give me on the ground?  thanks.

Timk49 is running the same combo as you, and he estimates his 4.10's to be the equivilent of about 3.80's

[DOGMAN]

Sorry it took so long for me to reply-but I've

been having computer problems. The truck is a 1500HD , 6.0 , 4.10s . The trailer is 4,000 lbs. What will my REAL world gas milage be doing about 65 & towing. What about empty doing 65. Thanks guys- glad to be back & you all have a great deal of knowledge & its great to be on the forum.

[DOGMAN]

i just drove the 4.10 , got into a 3.73 CC on the lot and drove that also..what a difference! 4.10s all the way!!

[JimWilson]

The truck is a 1500HD , 6.0 , 4.10s . The trailer is 4,000 lbs. What will my REAL world gas milage be doing about 65 & towing. What about empty doing 65.

My 2500HD with the 6.0 and 4.10's gets about 12-13 average (mixed city/highway). You should do at least that with a 1500HD because it's a bit lighter. Even more if you do a lot of highway driving.

 

And to answer you're original question; I would go with the 4.10's. If you lose 1 MPG over the 3.73's I'd be very surprised, but when you're towing you will notice the difference in performance. AAMOF, you might getter better mileage when towing because the truck will be able to stay in the "meat" of it's powerband a lot easier.