Fountain38

Need some Advice!!! I am looking at buying a 2004 powerstroke dually. I will be towing a 36 eliminator daytona. I realize the 3:73 ratio gears will be fine but if I put 19.5" tires and wheels on it will I be better off with 4:10 gears to equal my effective Gear ratio that I need to pull with. Just confused as usual thanks

I wonder what the difference in fuel milege will be empty? Any comments??

KH0302

Man my brother has a 2000 F250 dually 4WD 4 door and he pulls a 3 axle gooseneck that weighs 9000 lbs. empty, has loaded it to 40K. I wouldn't mess with that truck, it'll pull your boat at 90 all day if you want. 4:10s are going to kill you mileage-wise with no benefit.

my $.001

bford1

19.5" tires??? huh??? Superdutys come with 265/75 tires which are about 31"tall. Do you mean 19.5" rims? If so what tire are you going to run? If you are going to jack it up and run 35" (tall) tires or larger then I'd go with the 4.10s. 35 12.50s on 16" or 16.5" rims are very polular and will fit with only a leveling kit.

3.73s will get better mileage. But, if you go with a really big tire 373s will fell like taller (highway) gears.

My 2000 F250 has 3.55s with 34" tires (295/75 16s). It pulls my 12,000# Formula 357 no problem.

Formulas for MPH RPM gears & tires
mph = rpm x tire diameter / gear ratio x 336
rpm = mph x gear ratio x 336 / tire daimeter
gear ratio = rpm x tire diameter / mph x 336
tire diameter = mph x gear ratio x 336 / rpm

Formulas for tire size & their effect
tire diameter = 2 x selection width x aspect ratio / 2540 + rim diameter
effective ratio = old tire diameter / new tire diameter x original ratio
actual mph = new tire diameter / old tire diameter x actual mph

Dock Holiday

I have a 2002 F-350 Power Stroke Dually with 4.10's.

Have just been checking my fuel numbers over the last couple of weeks and these are very accurate numbers.

Under 60 MPH Non-Towing and I have see 14.8MPG. This was a trip of almost 250 miles one way.

At 70 to 75 MPH on the interstate commuting to work daily, 22 miles one way non-towing and the best is 13.4 MPG.

Towing close to 11,500 lbs at interstate speed, 70 MPH and I am seeing the worst at 10.9 and the best at 11.8.

My truck is completely stock.

I like the 4.10 gears for this reason. I can tow in overdrive keeping the engine RPM's down and don't have to worry about it. It never down shifts except on really tall hills are if you are getting into it.

I was told that you cannot tow this kind of weight in overdrive with the 3.73's.

This is just what a dealer told me, not 100% sure if it is true.

Strip Poker 388

iTrader: (6)

The Chevy's only come with 3.73,No choice.


I would go with the 4.10 on the Ford.

Fountain38

Buford1, I was talking about 19.5 alum wheels that seem to be gettin so popular. I have seen a few dually with these tire/wheel combination and they look real good. I realize I would be changing my gearing with taller tires

boot

Like bford1 said , It depends on tire size . If they are close to stock size ,go 3.73's . I get 3 mpg difference on our 2 trucks with 4.10(14.5) & 3.73(17.5) and the 3.73 is quicker (0 to 100 or so ...... ) with the same load ! I pull 21,000 to 22,000 lbs no problem with 3.73's . Hell I just did it with an Excursion !! Plenty of power ! even stock ....

bford1 ,how did you get 3.55's in yours ? Where they still availible in that year ? My brother got 22-23 mpg with his 97 f350 with 3.55's and 33's on a hunting trip from NJ. to Va.

Here is a great calculater I use alot !! CHeck it out .
For transfercase ratio use "1" ,which is 1 to 1 .
for trans ratio use .75 or .73 , I think thats the overdrive ratio on these trans .

http://www.4lo.com/4LoCalc.htm

Scott B

I have several F350's, 6 spd with the 3.73's. They pull fine in OD, up to around 12k lbs. Disadvantage to that gear is posi is not available for whatever reason. The 4.10 is availabke in posi.

Currently I am pulling with a F250 PSD 6 spd w/3.73. I can tow 12k lbs down the road @ 70 mph all day long with no issues. Fuel consumption towin ='s the F350's MT, and when I am MT I have gotten as high as 21. I do average 17 - 18 usually.

Scott B

rbtnt

I have a 97 250PSD that I just changed from 3.55 to 4.10 with 16" wheels. My mpg went from 19-20 to 17-18 running 72 mph. I'm only pull 10K, but the new gears made a big difference.

boot

Scott, What year is the truck you couldn't get limited slip ? They ran out of them a few years ago .thats why . My 02 and 03 have it .

rbtnt, your right , 3.55 is terrible to pull with ! Great for running around though !

The thing is , the newer trucks have soooo much more power , you don't need low gears any more .

I am swapping form 3.70's to 3.36's ! ! With 40" tires !! Thats on my Kenworth though .......1650 ft lbs of torque helps !!