I have been researching the best solution for going from 3.73 - 4.30 gears aftermarket (Dealer wanted $2900!!!) and think I found my answer. Local 4x4 shop quoted me $1800 installed as the truck is new and shouldn't need the entire rebuild kit. I said I am in...dropping it off tomorrow to get the work done. At $1800 I can fully justify it in my head and I also plan to to move to 34" tires while pulling up to 8k so I think the 4:30 should serve me will.

 

That's a great price. My dealer wanted about $2900 also. I am really looking forward to my new truck coming with 4.30's. Enjoy

 

What can I expect going to the 4.30? Can I assume picking up 1 gear across the board?

What I am getting at is that when I pull my trailer (7500-8k) going up the main pass I have to go over (5-6% grade) I have to drop down into 2nd gear at around 5k RPM to cover the hill at around 50-53 MPH...Can I expect to now be able to take that hill in 3rd? What is the general driving like starting out in 1st and 2nd gear?

I have a 5star 87 tow tune - will I need to get that modified for the new gears?

 

My 5star has a prompt for gearing and tire size so I think you will good there but you could still call them and ask.
What size tires are you currently running?
I use this calculator quite a bit to play with rpms vs gearing/tranny gear/tire size.
https://www.ringpinion.com/calculato...x#Transmission
The 6r140 tranny gearing is:
1st - 3.97
2nd - 2.32
3rd - 1.52
4th - 1.15
5th - .86
6th - .67

 

I recently saw this on a construction website:
Ford offers its 6.2-liter gasoline engine with a 3.73 or a 4.30 axle ratio. "[For] anyone who will tow or do something with a heavy load the majority of the time, we have noticed that with a 10,000-lb. trailer, the fuel economy is significantly better -- in the mile-plus range -- when towing with the 4.30," states Tim Ogilvie, fuel economy engineer.

"The physics behind that is, with the 4.30 axle ratio, you're in sixth gear more of the time," Slevin explains. "With the lower numerical ratio, you are more likely to be in fifth or fourth."

I tow 8k and use 2nd more than I would like. 3rd just can't quite hold the grade pulls. By going to the 4.30 you pick up 500 rpms and I think for my load will be enough to larger reduce my 2nd gear downshifts.

 

I too am dropping off my truck tomorrow to get re-geared to 4.30's. I'm using the Nitro Gear set. Total invested 2155 including Gear oil and new front axle seals, nitro master install kit and labor.

And yes the SCT x4 from 5star does allow you to swap axle ratios. I'm using that as well.

 

Any truth to the rumor that most shops can't install these 100% as needed which result in excessive gear whine? I read that in another forum here. Bucks 4x4 is a top notch local shop who I am taking it to.

 

The whine will depend on how good of a gear set they install, I'll assume Dana and how good the mechanic is setting them up. Don't forget to do the break in as they tell you.

I have a '16 F350 dually Tow Boss which has the wide front axle and 4.30 gears. I did install 34" Michelins which brings your rpm level down to about a 3.73 or so. Here's the rpm's you can expect in 6th gear with a 34" tire......give or take a few.

65 mph = 1845 rpm, 70 mph = 1987 rpm, 75 mph = 2130 rpm, 80 mph = 2271 rpm, 85 mph = 2415 rpm. Good luck.

 

It depends on how much time the shop takes getting the gear pattern and backlash set correctly. That's why you usually get quoted 8hours per axle. Because it can take up to that amount of time to re-shim and check a pattern several times depending on the starting point. I really wanted to do this myself, but I dont have time to do it with my work schedule and travel.

 

The shop will using the Nitro Gear kit...Talked with them today and they said they have had great luck with that kit and no complaints of gear whine. Should be in the shop for 2 days.

After I get the truck and do any required break in procedures, I will be installing 295/70/18 tires on the stock wheels and reprogramming the 5 star tune to adjust accordingly.

 

You won't need any modifications for the tune. Don't try to put in 4.30 gears in the tuner or you will get check engine errors. Honestly after I switched over from 3.73 to 4.30s I took the tunes off as I felt it ran really good without. Picking up a gear shouldn't be a problem on most hills either even on slight inclines that I used to drop a gear or two I rarely drop any gears now.

 

Love my 4:30 gears. Old 3:73. Pull a real load in od 65 70 no problem.

 

Any updates?

 

Hah, yeah. I just picked up my truck, with a nice custom exhaust, but still running 3.73's.

Turns out my truck didn't fit on the guys lift, so he gave me a hell of a deal on a custom exhaust instead. *shrug*

I took the money I was going to spend on the install and bought an Eaton Truetrac to go in the rear end and I'll be installing it in the garage starting Friday night.

 

What did you have done to the exhaust? And do you not have the factory locking rear?