atwowheelguy

With the new 3.5 EB with the 10 speed, the 3.55 is the Max Tow Package ratio. The 3.73 is only available with the Heavy Duty Payload Package.
The 3.31 with the ten speed has the same first gear ratio as the 3.73 with the six speed, but the 3.31 is only available with the 4x4.

johndeerefarmer

Get the 3.55

tcp2

2017 3.5 has max torque at 3500rpm:

375 hp @ 5,000 rpm, 470 lb-ft of torque @ 3,500 rpm.

2016 3.5 has max torque at 2500rpm:

365hp @ 5000 rpm, 420 lb-ft of torque @ 2500 rpm.

2017 graph:

http://5startuning.com/got-2017-f150...ost/#iLightbox[gallery_image_1]/0

2016 graph:

http://5startuning.com/got-2015-f150...ost/#iLightbox[gallery_image_1]/0

WXman

Based on that spreadsheet I'd go with the 3.55 gears. Why? Because you're getting more of an advantage in the lower gears of the trans, but you're still running less RPM in 9th and 10th for better gas mileage. Best of both worlds.

With the 3.15 ratio, you're not gaining as much because the final drives are more similar in the low gears and you'll rarely ever see 9th and 10th used. Kind of wasteful.

atwowheelguy

What's the evidence that the 3.15 will rarely ever see 9th and 10th ever used? I only tow the camper for 8% of the mileage the truck is driven. To get the 3.55 requires the Max Tow Package. Does this mean that every 6700 lb. camper now requires a Max Tow Package F150? I don't need more of an advantage in the lower gears. The 3.15 ten speed first gear is the same as the 3.55 six speed first gear, which has proven to be plenty good enough to get my 6700 lb. camper moving from stopped. The way I see it, with the 3.15 ten speed, I will be giving up nothing from what I have now in the lower gears, which is plenty good enough, but will gain highway mpg. With the Max Tow 3.55, I would be giving up highway mpg to get MORE low gear pulling power, which I don't need.

If you ever get a chance, drive a 3.5 EB and see just how much different it is from a 5.0.

D_Cantrell

Go with the 3.55 gear. The 3.55 has a better mechanical advantage than the 3.15. I can tell you it does not matter what your transmission gear ratio is, the final power multiplication happens with that final drive gear. The chart may tell you that the 3.15 will equal the 3.55, but some weight on it and that 3.15 will rear its ugly head. Just my thoughts, have a good day, and best of luck.

zx12-iowa

Ok you seem a bit set on the hwy gears and somewhat argumentative about it. Towing is more than moving the first few feet. Also the 10 speed skips gears and has more overdrive gears. Compare gear ratios throughout the speed ranges. If you are asking if you an get by with hwy gears and occasionally tow your trailer - yes. Your current set up will pull it better bc of the rear gears. If you don't want the best towing vehicle....then get the hwy gears.

5star

iTrader: (1)

We have two 2017 F150 3.5L with 3.55 gears ones a 4wd and ones a 2wd . They both get better real world mileage than the 6 speeds and have great accelerations rates out of the hole with the new 10 speed. The 4wd truck pulled 10k lbs bumper pull trailer from SC to TX and back. Stayed in 8th or 7th gear most of the way there and back, just info. I think the 3.15 would pull 5-6k lbs ok in those 7/8th gears at hwy speeds. my 2 cents.

dannytexas

I assume these two trucks are not tuned. ha
Seriously, are these hwy gears you stated (7th/8th) while towing with stock tune or 5*?

And if currently tuned do you recall what gear the transmission was running on stock tune @ ~75 mph hwy? Did it settle into 10th and hold or does it really jump between 7-10th to maintain RPM?

BTW- love your products, my 13' has been running them smoothly for 4 years now.