3.55 or 4.10??? Towing a gooseneck horse trailer ~ 15000 lbs. 2017 F-350 super duty diesel drw.

 

Not that I'm an expert by any stretch but I would say 4.10 over the 3.55. Personally I would rather have the 3.73 over the 4.10 because you can lock out the 6th gear and be pretty close to the 4.10 when towing heavy.

 

4.10. I'd recommend 3.73 but you can no longer get that.
IMHO 3.55 is just to wrong in the other direction.

 

The 3.55 would tow your setup ok. It might seem lazy on take off but not an excessive amount with the current (2017) 6.7L torque and hp ratings. The 3.55 will give you better fuel economy without a load and probably not a significant amout less when towing.

Also, sometime to consider is how often you tow your rig. Is it over 50% of the miles you will put on the truck or less?

What does the 2017 Ford Tow Guide say about the 3.55 gears and load?

http://www.fleet.ford.com/resources/...de_r4_Feb7.pdf

My 2 cents say is a toss up and my selection would be judged by the amount of miles loaded verses unloaded.

 

I would also throw into the equation the speeds you normally tow at. If it's 55 MPH two lane roads, then I would lean toward 4.10's. If it's typically highway at 65+, then 3.55's would be better.

 

I have had 4.30, 4.10 and 3.73 dually. The transmission changes along the way, not only in lo, but also in overdrive, had as much impact as the rear axle.

Did the 17 change the transmission shift points and OD yet again? Depending upon what was done it could improve power with the 3.55 or not, or improve mpg with 4.10, or not.

I suspect the 3.55 is all about mpg running empty.

Loaded with my 17k 5er I am at max gcwr, and because of pin, the gvwr too. So, while "towing chart" would imply the 4.10 would allow more weight, I was boxed in.

I hardly noticed the weight on takeoff with the 6.4 with 4.30. The 4.10 a 6.7 in 2011 , about the same with dramatically better mpg empty and pulling. The OD transmission transmission did this, and also the better 6.7 engine emission design.

Both those trucks had the wide front axle, allowing a much smaller turning circle. I do miss that a lot, but it was not available with the 3.73 I now drive, and I thought how much wider of a circle could it be?

Empty 2015 with 3.73 gets consistent 1.5 mpg better at highway speeds than a 4.10. Towing, maybe, repeat maybe 0.5 mpg better on the flats with no wind. I rolling hills or in high frontal winds against my 13 foot 6-inch tall tall 5er, the 3.73 downshifts, which the 4.30 never did, and the 4.10 very, very rarely did. Pulling steep mountain passes with that load, the 4.10 was a lot better than 3.73. Shift points just seemed to match power needs better. So in those conditions it is a wash mpg wise, or slightly better in the 4.10, with drivability much better in the 4.10.

More power in the 17 engine won't help in my load constraints but transmission changes might.

The 4.10 would probably run cooler regardless, and that axle is de-rated by Ford versus what it's rating is in other applications - a real plus if you always tow heavy..

I moved to the 3.73 because unlike my early days of 90% towing, I found my use at about 50% empty running. Still very little in town or idling. I guessed I might get an extra 2 mpg with the 3.73 because of reduced rpms at highway speeds, and that would add up to $ over 50k miles (50% of 100k). I was close, reality was 1.5 mpg.

If the wide axle is available on the 3.55, AND transmission changes in first an 2nd gear help takeoff and changes in gears 4-5-6 help highway rolling shift points, I would go with the 3.55. If either is not only case, I would go with 4.10 with my 26k combined load.

If you are alone in your truck with no tools or family versus how I travel, your 2k lighter trailer could mean 3-4 K lower combined load. I do not believe a lower wind profile or 2k weight difference would change my option on gear ratios. 4 K lighter definately would move me towards the 3.55, so long as I could get the wide axle on the 3.55.

If you will always be in the country, the wide axle may not be so important, but backing and maneuvering a 40 foot 5er is tough work in a lot older campgrounds.

 

I'm in the "how often you tow, is it 50% of your drive time?" camp.

I tow my work trailer almost 100% of the time the truck is driven, so if I were in you're shoes I'd lean towards the 4.10.

Also, I agree that mainly interstate running would lean me towards the 3.55 just for the noise and fuel benefits. But if you're never on the interstate then 4.10 would be great. With the 3.55 and 20" wheels on my truck I spin ~1600rpms cruising at 70mph which is very quiet and the most fuel efficient. I think a 4.10 would spin around 2200 and I really don't think I would like that on a regular basis. It is much louder (even though the engine and truck are very quiet, it's just a relative thing).

 

my 3.73's is about 1750 rpms at 65 mph.

 

It depends on how much you tow. I had the 3.55 on my previous F-250s and I would get 10 to 11 mpg towing my 5th wheel. I just got a 2017 F350 DRW with the 4.10s and I get <10 mpg towing, usually between 8 and 9 doing 65-70 mph on the freeway. I thought my SRW 3.55 250s pulled my RV pretty well and I was happy with the mileage, so if I could do it over again I'd op for the 3.55s on my new F-350.

 

I had a 2005 with the 4:10 and I have a 2012 with the 3:55 that I tow the same 44' gooseneck car trailer with. The 3:55 gets better mileage both towing or empty and I can't feel any noticable differnce driving up and down the hills around Nevada. Going from Vegas to Tonopah NV ( going up in elevation about 4,000 ft overall) I get about 7.5 MPG coming back I get about 11.5 . I will get 3:55 gear in my next truck too

 

You cannot compare the tranny in a 2005 with the # of gears and OD in a late model setup.

The wind turbulance/drag of a car trailer at highway speeds is probably just as bad as a high profile 5er camper, but what does it weigh on the scales? That total weight affects rolling hills and mountain pass climbing performance and mpg.

 

TBH, there are too many questions left unanswered about what you seek.

No one can tell you what is right for you, but we can probably help you make a better selection.

You need to assess how often you'll be using this to tow that load, versus doing other things. If you tow this load often, and expect good acceleration, you'll want to get the 4.10. But if you do this infrequently, or don't have a penchant for hauling azz, then the 3.55 will do fine. Even the truck with 3.55 are rated to tow something like 25,000 pounds! You being at 15,000 pounds have PLENTY of tow margin.

Next, you'll want to know what terminal speeds you'll travel? Like others have asked, are you primarily doing back-roads or highway? Taller gears for highway.

Do you live in or drive towards a hilly areas? Bias to the 4.10 if very hilly or mountainous.


Overall, this is a matter of what you want versus what you need.

You'll get more pulling force per tranny gear with 4.10, but sacrifice speed and economy.
You'll get more speed and economy per tranny gear with 3.55, but sacrifice pulling force.

The real difference for your situation probably isn't enough to warranty any worry; either will do fine. You just need to define which is most important, and then realize the rest is a compromise.

There is no perfect answer, any more than there is a perfect truck. If it existed, the perfect truck would have:
- 1000 ft-lb at idle
- get 28 mpg combined
- be as long as a school-bus to get all your gear and buddies in it
- be as short as a Beetle to park in Walmart
- 50,000 mile oil and filter change
- cost less than your first house
- be able to tow your first house
No such beast exists, although each generation of truck gets better!
We're not there yet, so you're going to have to compromise somewhere.
Research all your inputs, and then pick the gear that best fits the majority of use.