Ford F-350 DRW axle ratio for pulling 42 foot 5th wheel

[DMacLeod]

I'm looking to purchase a Ford F-350 DRW diesel to pull a 42 foot 5th wheel. One thing I'm not sure of is the axle ratio. It looks like the F-350 has an option of 3.55, 3.73, 4.10, and 4.30 axle ratio's to choose from. What are the pros and cons of the different ratios? If you had to choose one, which would you choose?

thanks

[Old-Biscuit]

Ford VIN Decoder
https://www.vindecoderz.com/EN/Ford/F-350


Differential gearing.....
Depends on what transmission you have
Lower Gear Ratio (higher numbers) allows for higher 'tow ratings' but doesn;t change RAWR/Tire Max Load Ratings


4:10 will 'pull' better then 3:55

4:30 will 'pull' better then 3:73


Right transmission and 3:55 are good choice (10 speed)
6 speed and 3:73 good match

4 speed tranny----3:73 OK, 4:10 better, 4:30 a bit overkill unless very heavy weights are being towed


I have a 4 speed auto so went with 4:10 in my Dodge 3500 vs the 3:73 cause I was towing at MAX

Fuel mileage was 15/16 mpg non-towing and 10 towing 14K 5vr (2007 vintage)


New trucks do better


Details of truck you are buying???

[n0mad]

Originally Posted by DMacLeod

I'm looking to purchase a Ford F-350 DRW diesel to pull a 42 foot 5th wheel. One thing I'm not sure of is the axle ratio. It looks like the F-350 has an option of 3.55, 3.73, 4.10, and 4.30 axle ratio's to choose from. What are the pros and cons of the different ratios? If you had to choose one, which would you choose?

thanks

How heavy is the trailer? I'd go with 3:73 or 4:10, 3:55 with the 10 speed may not be bad. 4:30 will probably be annoying driving unloaded on the highway, unless it's necessary (which it probably isn't).

[tuffr2]

I had a 2012 F-450 and I thought the 4:30 gears made that truck unpleasant to drive solo on the highway. The truck was not happy unless it was towing.

I now have a F-250 with 3:73 gears and this truck is a much better highway cruiser.

Both the 2012 F-450 and this 2017 F-250 only had/have a 6 speed transmission.

If you get a 2020 truck with the 10 speed I am thinking 3:73 or 4:10 gears would be good towing gears. I am not towing super heavy so I would get the 3:73 gears but towing super heavy I would buy a truck with 4:10 gears.

[Dieselguy4]

New F350 drw diesels only come with 3.55 or 4.10s. Go with 4.10s for a 42 ft 5th wheel. Now the new 10 speed has a .632 overdrive while the 6 speed has a .674 overdrive. My 40 ft 5th wheel weights 13k lbs. I am at 21700 lbs running down the road. I spec my truck to run at 65 to 70 mph with my 5th wheel. I run just under 2000 rpm at 65 mph and just over 2000 rpm at 70 mph. It stays in 6th gear and i run cruise control. With 3.55s i think it would upshift allot running cruise. I get 9 to 11 mpg towing and 16.5 mpg empty. I would buy 4.10 again. It is a towing machine

[keymastr]

My 28' fifth wheel weighs over 13,000 pounds so your 42' will likely be heavier. I would get the 4.30 if available. The new trucks do not have much give up in mileage for the taller gears and will be much better for heavy towing.

[xrated]

I have a 2016 F350 Dually with the 3:73 rear end and I tow a Momentum 394 (20,000 lbs GVWR). I'm loaded to between 17,500 to 18, 600, depending on whether or not I've got the Cam Am Spyder in the garage or just taking bicycle for our outing. The 3:73 rear end in my F350 tows it just fine and depending on the terrain, I'm seeing about 9 mpg and unloaded I'm in the 16.5 to 17 mpg range. The Momentum is a triple axle and has a height of 13' 5" so lots of frontal area to the trailer, which affects mileage a lot more than total weight.

[37driver]

I pull a 42’ fifth wheel that weighs 16k with a 2015 F350 2 WD DRW Crew Cab
with 3.55 gearing and it pulls it with ease. Unless you’re getting up into the 20k range and above you’ll be fine with 3.55 gearing.

[DMacLeod]

Here's a little more information. The 5th wheel we're looking at is the Momentum 397TH, it has a UVW of 15,500. From the responses so far, it sounds like the 4.10 is the preferred ratio.

thanks

[450Donn]

Pulled my 13,500 pound fiver with a 4.10 rear end dually. Never ever regretted that decision in 13 years. The 4.10 will push you into the motors power band nicely making it far easier to float over the hills and maintain road speed.

[Jshopes81]

My thoughts.... 3.55 if you just need the 350 for the payload but arent dragging any more than gvwr, 4.10s if youll be pulling anything more than a few thousand pound. Anyone that says their 3.55s pull fine honestly just doesnt know any better and theyd be shocked what the extra gearing does.

[cactus]

Originally Posted by Jshopes81

My thoughts.... 3.55 if you just need the 350 for the payload but arent dragging any more than gvwr, 4.10s if youll be pulling anything more than a few thousand pound. Anyone that says their 3.55s pull fine honestly just doesnt know any better and theyd be shocked what the extra gearing does.

X2 for the 4.10`s

[jjackrash]

What year truck?

The 2020s with the 10-speed have sick power. My 2020 GMC with the 10-speed has 3.42s in it IIRC and I would not change a thing. I towed a 17k lbs. flatbed the other day and it didn't blink on a pretty stout grade. I have not towed my 19k fiver yet, but I have no concerns about the ratio or the need for more power.

[xrated]

Originally Posted by DMacLeod

Here's a little more information. The 5th wheel we're looking at is the Momentum 397TH, it has a UVW of 15,500. From the responses so far, it sounds like the 4.10 is the preferred ratio.

thanks

Your 397TH is almost a duplicate of my 394M. 20,000 lb GVWR, unloaded weight at 15,500 lb, triple axle, 13' 5" height and made by the same company. As I posted earlier, the 3:73 in my Dually does just fine with this trailer and realistically, it is more about frontal and height of the trailer than the weight when you are talking 18, 19, 20,000 lbs in tow.