I've seen this same debate for years regarding the V10. I have some experience with the V10 and the 6.2 is very similar.

The 4:30's will outperform the 3:73's in every phase of driving. People always say you might get better in town mpg with the 3:73's, and you might slightly, but I can be in 5th gear by 40 mph. You can't do that with the other gears.

Towing is where you will notice the biggest difference. Mine is at 2250 rpm's at 70 mph. It rarely downshifts to pull smaller hills to maintain speed. Not to mention off the line gear multiplication.

Empty, on the highway, the 3:73's will probably do a little better. Maybe... But why not configure your truck for the best performance and take a very slight hit to mpg?

How many threads have you read about trying to increase performance? Getting the 4:30's right off the bat is the best money you will ever spend.

 

4.30s...I don't think there should ever be a debate

 

4.30's all the way! I love mine!

 

If I had to do it over again I'd choose the 3.73's. I'm averaging 9mpg and my bud has the 3.73's averaging 13mpg with the same truck configuration. If you stay with stock tires 3.73's will do the job just fine.

 

I ordered my 2013 with 4.30's and I rarely tow with it. Reason I went this route was to offset larger tires if I wanted to go that route in the future. Driving local and keeping my speed around 60 I average 11.5-12 in the winter and gain about 1mpg in the summer. The truck tops out at 14mpg on long trips if I do my part.

 

Pick the gear that let's you climb at the speed you want at the RPMs you want. Once your rolling, the only thing that matters is the HP of the engine. If I was towing at the limits of a 6.2, I'd want the rear that let me climb at 65 MPH at 4800-5000 RPMs. Unfortunately, that isn't an option with the transmission gears / tire sizes / axle ratios offered by Ford on the 2017.

An example: 20" tires, 596 turns / mile, Torqshift-g (2.34 2nd, 1.52 3rd)
4.30 climbing up to 6K RPMS
55 MPH --> 2nd gear @ 5500 RPMs
60 MPH --> 2nd gear @ 6000 RPMs
65 MPH --> 3rd gear @ 4220 RPMs
70 MPH --> 3rd gear @ 4545 RPMs

3.73
55 MPH --> 2nd gear @ 4770 RPMs
60 MPH --> 2nd gear @ 5202 RPMs
65 MPH --> 2nd gear @ 5636 RPMs
70 MPH --> 3rd gear @ 3942 RPMs

Hopefully it is clear that the 4.3 will pull stronger at 55 - 60 MPH, from 60 MPH - 69 MPH, the 3.73 can hold 2nd gear and stay below 6000 RPMs, it will pull a lot stronger than the 4.30. When you need to shift the 3.73 to 3rd at 70 MPH, the 4.30 wins again.

Having towed near the limits of a gas motor for years, I can tell you that it isn't the gear in the back that matters, it's the final drive ratio that puts you at the RPMs you want to climb that matters.

For me, I'd get the 3.73 in this scenario as I like to climb at 65 MPH, and the 3.73 at 5636 RPMs will significantly out pull the 4.30 at 4220 RPMs. If I had a smaller 5th wheel, say 12,000# loaded, I'd get the 4.30 because it would likely hold speed at 4220 RPMs and that is more pleasant than screaming the engine at 5636.

Personally, I'm most interested in how the truck performs at the task that made me choose a super duty, rather than mileage. I'm sure the 4.30 gears in the F450 I ordered won't be the ideal fuel sipping choice

I hope this helps.

 

I would say if you're going to tow heavy a lot or put on bigger tires than go 4.30's. I ordered mine with 3.73's and I have no regrets. I've pulled an 11k trailer a few times with no trouble. I get 16.5mpg highway and average 14mpg combined with stock 32" tires.

 

I can't find a dyno chart for the 2017 6.2L. Looking at the 2015 dyno chart, which won't match the 2017, the 'meat' of the power (torque) looks to be between 3800 and 4900 rpm. I think the 4.30 pulling in 3rd will do just fine in my truck:

4.30 climbing up to 6K RPMS
3800 rpm --> 3rd rear @ 55 mph
4600 rpm --> 3rd gear @ 67 mph
4900 rpm --> 3rd gear @ 72 mph

 

You don't pull strongest at peak engine torque, you pull strongest at peak engine hp.

 

So, right at 5700 rpm for the 2015~2016 6.2L trucks? Would still like to see a dyno chart for the 2017s.

 

Thanks for all the great info, I will be pulling a 12,000 to 13,000 lb RV and plan on being out for about a month at a time towing from South to North and East Coast to West Coast. After reading and rereading all the post I believe I will be going with the 4.30. I plan on running 60 to 65 most of the time. (I won't be in a hurry in retirement). Again thanks for all your comments.

 

Couldn't agree more. If you really want a tow vehicle drive through a campground on a holiday weekend and see what the majority of folks are towing with.

You will see diesel after diesel and chances are most of them have a Ford SD with the 4:30 gearing. That "other" brand will have the 4:10.

Another thing about those who tow big rigs, 5th wheels. When they are together at the campfire talking about camping at least two topics just DO NOT come up:

1. the cost of (diesel) fuel
2. mileage

It is just the COST OF RV'ing. Its a given. No sense complaining.

JMO.
bigdon68

 

220, 221, whatever it takes.

 

You're making the right choice and if you want more assurance you should go to the 6.2 section but you're going to hear the same thing

 

The 4.30 rear gives me a substantially higher tow rating. I went with it for that reason and because the majority of folks that have actually hauled with the 6.2L prefer the 4.30.