3:31 or 3:55

Jguetch wrote:
Anyone see a big difference between the ratios?

Either truck with a 9000+ tow rating will do the job for a 6500-7500 lb trailer. Get the one you like best.
Doing the math on tranny gear ratios vs 3.31 and 3.55 drive axle ratios shows about 200-220 rpm difference through 3rd and 4th and 5th at 60 mph. The tranny shows to be the 6R80E that doesn't have a 1:1 direct drive gear but splits on both sides. Makes the 3.31 gears similar to the old trannies and a 3.90 gears all depending on transmission gear selection.

Skip all of the above options.The EcoBoost hasn't been on the scene long enough to prove it's durability in the world of long term heavy towing and if you look around the truck forums, you'll see some grumbling about them.. Are you buying a truck for the options or for the towing capabilities? You are going to run out of payload with the 1/2 ton.You may not think so now, but take it from someone who is on their third truck, you will. You'll load more gear, want a bigger trailer, etc. Forgo the leather seats, wood trim, and whistles and bells you really aren't going to need and put that $$$ on a 3/4 ton truck that will do what you need without worry.. You can always get a Focus for a grocery getter.

APT wrote:

Skip both and get one with the Max Trailer Towing package. You'll want the extra 350-450 pounds of payload for a family, some camping gear in the bed, and 900-1000 pounds of tongue weight.

Yeah, what he said.

-- Rob

mbopp wrote:
Look at the yellow payload sticker on each truck, and I think you'll see that you run out of payload before running out of tow capacity. Especially on a crew cab. Sorry, but I'd be looking for a Max tow / Max payload SCREW truck.
My SCAB works fine since it's just DW & me towing a small TT.

Bingo. A loaded F-150 with 7200 GVW won't have much of a payload. My Max Tow has 7600 lb GVW and leaves enough payload to get by, but I'm not planning on carrying much extra in the bed.

As far as differential ratio, I wouldn't worry too much about it since you plan on mostly flatland driving. The Eco should have enough torque in lower gears to meet your needs.

Check payload 1st. 4.10's won't matter if you don't have the payload capacity for the tongue weight, WD hitch, family and gear in your truck.
7400lbs equates to 9-950lbs for tongue weight. Then add 100lbs for the WD hitch. Now your at 1000lbs. If you aren't getting the Maxtow then your payload will be in the 14-1500lb range. Add up the family and whatever else goes in the truck and see how close you are. Where are you putting the BBQ, lawn chairs, firewood, etc.

Even the 3:55 is somewhat of an economy gear. With the EB it is no doubt capable of towing using an economy gear if you can justify it by your use. If the truck spends 95% of it's time driving to and from work then go with the economy gear (either one) but the higher your ratio the less fun towing will be. You'll notice the difference most in mountainous terrain.
Good luck / Skip

Those ratios are really pretty close together -- I'm not sure one could tell a big difference either way.

But you do want to make sure that whichever you choose has the upgraded towing goodies you will need. **disclaimer** I don't know a lot about how Fords come from the factory, or if there are options such as transmission or oil coolers that you will need to get the max tow numbers. But with GMs, the lower (numerically) gears usually mean the truck also lacks the heavy towing equipment as well.

you should make sure that the only difference between them is the axle ratio.

Good luck!

4x4ord wrote:
I have used my F350 with the 3.55 gears for hauling trailers over 30,000 lbs fairly regularly and have absolutely no regrets. If I was only going to be towing trailers up to 15,000 lbs or so I would want the 3.31 gears. Guys with the 3.31 gears are getting better fuel mileage than what I can get with mine. To put things into perspective the Ford 6.7 in low gear with the 3.55 rear end is capable of putting more torque to the rear axle than what two 2004 Cummins 5.9's hooked in tandem would be able to do with 4.10 gears.

sorry, don't know where my head was.

Look at the yellow payload sticker on each truck, and I think you'll see that you run out of payload before running out of tow capacity. Especially on a crew cab. Sorry, but I'd be looking for a Max tow / Max payload SCREW truck.
My SCAB works fine since it's just DW & me towing a small TT.

7500-8000 pounds loaded TT, bunk house for a family. Skip both and get one with the Max Trailer Towing package. You'll want the extra 350-450 pounds of payload for a family, some camping gear in the bed, and 900-1000 pounds of tongue weight.

That package includes 3.73 axle ratio, and is not likely to be found on every dealer lot, or one within 200 miles.

As for 3.31 vs. 3.55: I favor the shortest (numerically highest) axle ratio possible with gas trucks. The real world fuel economy difference is not measurable. The extra wheel torque is always butt dyno approved.