I recently purchased a 04 F240 SC SB 4x4 Lariat FX4 V10 with 3.73. Let say this, I work construction, live in my 37' 5er, and needed a way to get my 5er to the spring race in Bristol. I used to have someone pull it for me, out of time, out of options, so we went out shopping. If I had ordered from the factory I would have gotten 4.30's, beggers can't be chosers, that was the only sacrifice I made. As I said my girlfriend and I live in my 5er and it is heavy, don't know actual weight but heavy(dry 11.5k). I got the first 1k miles on the truck and hooked up and off we went. After watching several threads on here (realizing I needed the 4.30) I was well educated on what to watch for. Thanks Guys. I left OD turned off and I never went below the posted speed limit pulling the 5er, oh yeah forgot to mention, the 285/75/16 BFG can't be helping either. The best part was going up a good grade and passing others going to the same destination. Here is the mpg I have gotten on the first 3k on the truck. City 11.3mpg (1280 miles), Hwy towing boat 4k 11.5mpg (360 miles), Hwy empty 14.5mpg (360 miles). Hwy towing 37' 5er 6.3mpg (1000 miles). Thats is with a trailer that I believe may way 15k and the 3.73 gears. Let me say this, I will have 4.30 or better in the future because I believe I will get better gas mileage towing the 5er using OD. If you are worried about the mpg, you proabally don't deserve the V10. The V10 is a powerhouse. Goal for next trip: Slow down long enough to kit a scale!

You can have the house, the boat, and the motorcycle, but don't touch my woman or my V10.

 

Sounds great. I thought the 4.30 is not as good on gas as the 3.73 but pulls better? I love my V10 too.

 

The gas mileage comment is becuase I think if install the 4.30's I will be able to use OD on the transmission, anybody have any thoughts on this? Giving the drivetrain another gear to choose from certainly can't hurt gas milleage. There were times on the trip that putting it in OD was tempting, but did not want to risk it. It seems that the transmission in OD uses the torque converter alot to compensate when towing the boat and did not want to risk getting it to hot. I didn't buy it for the Gas Mileage, so I diffenately see some new gears in the furture.

 

Would 4.30's in OD equal 3.73 out of OD??? Hummm, somebody smarter than me will have to figure that out..

 

I am going to say, "No", due to the Overdrive factor. But, I have the manual tranny.

I tow on average around 12K to 13K everytime I hookup and even though I have to gear down on long, steep hills, I can leave it in OD most of the time and still travel the speed limit.. or beyond. I have 4.30's but also have installed 255/85 tires which bring it back down a little.

 

My experience tells me the V-10 likes 2200 - 2400 RPM towing heavy in OD. Below this RPM the motor seems to be down on power and wants to shift to drive. Speed will vary depending on gear ratio and tire diameter.

 

No they do not equal, these calcs are base on a 32" tire.

3.73 at 60 mph in D = 2350rpm
3.73 at 60 mph in OD = 1692rpm
4.30 at 60 mph in D = 2709rpm
4.30 at 60 mph in OD = 1950rpm

So the 4.30's are a comprimise.