Gear ratio??

Jesse_01 · May 21, 2014

So I figured out the rpm/tire/speed ratio.

Currently I am 3.31, here is the rpm break down for 70mph running 35" tires. I do 25% of my mileage towing, the rest stop in go in town. So I think I may benefit from the 4.10, especially if I go to a taller tire down the road.
3.31 1490rpm
3.55 1598
3.73 1679
4.10 1846

I really liked my 09, it had 3.73 & 35" tires running 70mph at 1780rpm.

Here is what is available from ford if I went that route for gears.

Differential
4.30 Ratio, 3.55 Ratio, 4.10 Ratio, 3.31 Ratio, 3.73 Ratio; Case Kit, Including Bearings

Jesse_01 · May 22, 2014

So my 2 options are 3.73(1679) or 4.30(1936 rpm).

Unless I went to a 37" tire than I would be 4.30 ( 1831rpm)

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TANK'S 250 · May 22, 2014

what chart did you get your numbers from....because most charts are based on 1:1, which is 4th gear

Nic · May 22, 2014

^^ WHS. I would stick with a 3.73. Nice all around gear. For 37s, I would think a 4.10 would be just fine.

TANK'S 250 · May 22, 2014

I guess I should have also asked..

......what is your end goal?
...more low end torque?
...better towing/city mileage?

....because regearing is gonna cost around $1,000 PER axle....which is $2,000....that may take quite a few years to see any "recouping" of the money you put in.

Jesse_01 · May 22, 2014

Towing 10k trailer, and city driving. I live in the mtns also.

I used a formula with od gear, tire size, speed, diff gear. 6th gear is .67:1

I can swap out to 3.73 or 4.30 diffs out of a gas truck for $1100

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TANK'S 250 · May 23, 2014

Always towing, city driving, and mountains....get the 4.30's....your trans will thank you

Jesse_01 · May 23, 2014

TANK'S 250 said:
Always towing, city driving, and mountains....get the 4.30's....your trans will thank you

I was kind of leaning towards that. Worse comes to worse I could always put on 37's to lower the rpm.

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RedRice589 · May 23, 2014

At least 4.10's I'm gonna go 35's and I want to regear. Had them before and hated it. 4.10's at least.

Jesse_01 · May 23, 2014

Can't get 4.10 on 11+. From ford anyways.

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RedRice589 · May 23, 2014

I guess I ll lose my e-locker....

Randy_270 · May 23, 2014

4.11 or 4.30 gears and you can keep your e-locker

http://www.dieselpowerproducts.com/...omplete-package-11-13-ford-superduty-srw.aspx

RedRice589 · May 23, 2014

Randy_270 said:
4.11 or 4.30 gears and you can keep your e-locker

http://www.dieselpowerproducts.com/...omplete-package-11-13-ford-superduty-srw.aspx

Annnnnd I need more money!!

Randy_270 · May 23, 2014

I know exactly how you feel lol

Jesse_01 · May 24, 2014

You can get ford oem ones in a kit for cheaper than that. Never heard of nitro gears either.

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Trevor008 · May 24, 2014

I would do the 4.30's for sure. Correction... I WILL do the 4.30's for sure.. Lol

I know diesels are different and do better at lower rpm's but I had 4.88's in my F150 with 38's and it worked out good all around. My city mpg's were better than when the truck had 32's and 3.73's and my highway mpg's were on par with stock. Truck just felt right too