Towing with 3.31 gears

[jfoster41]

I've been thinking about upgrading from an '01 F150 s-crew to a new SD , but not sure what gears to get. I have read blogs where folks are getting 19-20mpg with 3.31's, but not much info about towing with them. It would be a daily driver, mostly highway, but I'm not sure what the sacriface would be, if any, when pulling an 8000lb RV. Any thoughts?

 

[DaveBen]

That is not very different from a car (1965 Chevelle) I had with 3.08 gears. They were very high and I was a kid so no drag racing for me. Pulling any trailer will be very difficult with 3.31 gears. You will be stressing your tranny when you are pulling. I would go with 3.55 at least.

Dave

 

[WD40]

If your going to be getting a 2012 F-250 or F-350 I think I would be with Dave on the 3.55 gears for 8000lb trailer should work out good.
I pulled a 8000 fifthwheel years ago with a old 460 CCSRW and 3.55 and didn't do to bad back then. I may have had 210 HP and 225 TQ
back in 84 or 85 F-350.
Doug

 

[BJS]

I'll say go for it, They are giving you 12.5-14k depending on options with the 3.31 gears. You'll be a bit more sluggish than higher (numerically)gears in the hills and city traffic will warm your trans quicker when towing. but as a DD and occasional tow rig the 3.31's are a good match. though if you plan on a larger tire you really will want to consider a different ratio in the future. I've debated looking for the 3.31 ratio to swap into my truck if I ever go back to a smaller tire.

Here's some numbers for you presuming 34" tires or 275/65/20 and a 3.31 rear

***************************************
Gear MPH/1000 MPH @2000 MPH @3500
***************************************
1 7.72 15 27
2 13.20 26 46
3 20.15 40 71
4 26.64 53 93
5 35.62 71 125
6 45.72 91 160

same tires w/ 3.55

***************************************
Gear MPH/1000 MPH @2000 MPH @3500
***************************************
1 7.19 14 25
2 12.31 25 43
3 18.79 38 66
4 24.84 50 87
5 33.21 66 116
6 42.63 85 149

and finally 3.73 gears
***************************************
Gear MPH/1000 MPH @2000 MPH @3500
***************************************
1 6.85 14 24
2 11.72 23 41
3 17.88 36 63
4 23.64 47 83
5 31.61 63 111
6 40.57 81 142

 

[hdjeff]

you would have a better mechaical advantage with the 3.55 but with 800lb/ft of torque, this thing pulls strong. I have the 3.73 but I think thats a DRW only option. Only 700 miles on her and Im getting 18+ highway. Im amazed at the power and fuel efficiency so far.

 

[DaveBen]

3.73 come on all trucks.

Dave

 

[RoyBoy]

3.73 come on all trucks.

Dave

No Dave, 3.55 and 3.31 are the new standard on the 2011 and up SuperDuty trucks.
3.73 on F-350 Duallies and 4.30 on the F-450 pickup.

 

[DaveBen]

Thanks Roy. Now I know.

Dave

 

[Nasty]

3.73 come on all trucks.

Dave

May I beg to differ...I have 2 2011 F250s ..both with 3:31s. We pull a 15000lb trailer 6 days a week with no problems..in fact I would like to have a button on the dash where I could dial down the power in the winter when its dicy roads. Also pulled my 35 5thr over the Rockies last summer with no issues. Fuel economy is fine and still plenty of power. Truck One just passed the 310,000k mark with no problems..second one has just 85000 in 9 months. I wish they offered 3:08s


My profile needs updating

 

[jfoster41]

Hey Guys,
I'm sorry for the delayed repsonse, it's been a hectic week. I appreciate all of your input and I think I'm going stick with the 3.31's. My current F150 SC is our family vehicle and I don't see that changing with a new SD so fuel efficency is somewhat important (I know, I know...fuel efficency + 3/4ton truck= oxymoron). Anyway, I've got a test drive scheduled next Friday so we'll see what happens...