Axle Ratio, new truck

[blaczero]

Hey all, I think I know the answer but just wanted to make sure. I am looking into a 5th wheel ~15k GVWR and am buying a truck. I want an f350 and may order a new one to get exactly what I want (there are currently 0 trucks nationwide that match what I want).

I am going F350 DRW, 7.3L gas, crew cab 4x4 with 5th wheel prep. What I'm thinking is I'll go 4.10 axle ratio.

I work from home and my wife cannot work, so it's a "daily driver" but won't be driven daily. To make our dream work, we'll sell our vehicles and this will be our only one.

So bottom line, should I get the 4.1 ratio or the 3.73?

[jerem0621]

Get the gear ratio you can get the best deal on. You will not notice any difference unless you tow with both of them.

Thanks

Jeremiah

[4x4ord]

rhagfo wrote:

4x4ord wrote:
You’ve probably got your reasons for wanting a 7.3 dually but have you considered either spending another 7k and going with a SRW diesel? Or buying a slightly used diesel for the same money you’d be spending to get a gasser?

:S
Why go down to SRW from a plan to get a DRW gas TV, that doesn’t make sense!
The gas DRW will have about 800# more pay load to a diesel DRW, and and about 2,200# to 2,400# more than a F350 SRW.
I can see recommending a DRW diesel for pulling power, but the OP wants gas.

For what he is pulling he doesn't need DRW nor does he need a diesel. The dually might be nice while towing but the diesel would be reeeeeally nice; and the dually is a bit of a nuisance when not towing.

[rhagfo]

4x4ord wrote:
You’ve probably got your reasons for wanting a 7.3 dually but have you considered either spending another 7k and going with a SRW diesel? Or buying a slightly used diesel for the same money you’d be spending to get a gasser?

:S
Why go down to SRW from a plan to get a DRW gas TV, that doesn’t make sense!
The gas DRW will have about 800# more pay load to a diesel DRW, and and about 2,200# to 2,400# more than a F350 SRW.
I can see recommending a DRW diesel for pulling power, but the OP wants gas.

[lenr]

If the 10 speed heavy duty transmission can handle 1050 ft lb of torque from the diesel then it can well handle 475 ft lb from the 7.3 gas pushing a 3.73 axle. Also, 1st gear in the 10 speed is 4.615 up from 3.97 in the 6 speed. It's hard to believe that a 4.615 ratio connected to torque converter would have a hard time starting any load.

[way2roll]

justme wrote:
I would suspect the new 10-speed trany will do the job because of its extended torque ratios. However, I am concerned about gear hunting while pulling heavy loads and inclines. Seems to me gear hunting will shorten the life of the trany while doing a lot of towing or heavy hauling-- especially with gas engines.

My NEW F350 with the 10 spd tranny doesn't gear hunt. It's a diesel so perhaps that helps, but it's a very smart truck. It's built to tow and it does it very well. If there is a gear change, it's hardly noticeable. But usually climbing it finds the proper gear at the proper speed and just stays there not breaking a sweat despite changes in grade.

[C_Schomer]

Being it will be your only vehicle, I’d say 3.73 Unless you will be mostly towing in the mountains. That would be me! Craig

[justme]

I would suspect the new 10-speed trany will do the job because of its extended torque ratios. However, I am concerned about gear hunting while pulling heavy loads and inclines. Seems to me gear hunting will shorten the life of the trany while doing a lot of towing or heavy hauling-- especially with gas engines.

[ACZL]

My '15 F350 SWR,cc, 4x4 ,sb, 6.7 had 3.55 gears, 6sp tranny and it ran (I think...frigging CRS!) around 2,000 at 70 mph. The ;17 F350 DWR, cc, 4x4, 6.7, 4.10 gears, 6 sp tranny is at 2100 rpms at 70 mpg. Towing rig in sig, it's getting 8.5-9.0 mpg. It's true the gasser will not get as good as mpg towing as a diesel will, but consider down the road and you want to get a bigger RV. The 4.30 will be better for the whole truck. I like the idea another poster mentioned about considering a used SWR or even a DWR diesel. If sticking w/ Ford, 3.55 w/ the 6 sp and heard that w/ the 10 Spd they are utilizing 3.31 gears. My '17 was an off the lot purchase and came w/ 4.10's. I would have liked to have 3/73's, but overall, happy w/ the 4.10's.

[4x4ord]

You’ve probably got your reasons for wanting a 7.3 dually but have you considered either spending another 7k and going with a SRW diesel? Or buying a slightly used diesel for the same money you’d be spending to get a gasser?

[blaczero]

Thanks everyone for their response, I learned a lot.

[Let_s_Go_Explor]

I've always ordered a 4.30:1 (or similar) rear for the tow vehicle. Less strain on the drive train / added torque when you need it. With the new 10 speed transmissions, you don't seem to pay has heavily mpg-wise as in the old days for the 4+ gears. (I just ordered a new F350 with the 7.3L engine and 4.30:1 rear. )

[goducks10]

You couldn't pay me to tow 15,000 with a gasser. It would be nice if you did as it would help offset the terrible gas mpg's.

[rhagfo]

Michelle.S wrote:
Here's the 1st gear ratio for GMs 6 speed Allison and the new 10 speed:
New 10 speed 4.540 : 1
Old 6 speed 3.094 : 1
So with the lower first gear the 10 speed will give you the same overall pulling power with the taller differential gears.

If I wanted to pull a 15,000# 5er with a gas engine I want all the advantage I could get. The 3.73 gives 17,000# pulling capacity, 4.30’s gives you 20,000#.
My 2016 Cummins with six speed, and 3.73’s gives me 25,024# of pulling power, next 5er will likely top out at 17,000#.

[Michelle_S]

Here's the 1st gear ratio for GMs 6 speed Allison and the new 10 speed:
New 10 speed 4.540 : 1
Old 6 speed 3.094 : 1
So with the lower first gear the 10 speed will give you the same overall pulling power with the taller differential gears.