Rear Diff. Question for 3.73 ratio

[350DingBat]

Hi guys,

I need to see about getting some lower gears for my diffs.

I run Toyo M/T's 38x15.5x20, with D1 (3.37) diff. gears.

What ratio would you guys recommend? (4.10, 4.30???)

I do a fair amount of towing, and this ratio, plus my large tire size, is KILLING my power!
She dogs on the bigger hills thats for sure.

Any and all opinions are welcomed.
Thanks guys.

[350DingBat]

Wow...

25 people have looked at this thread and NOBODY can give me a suggestion?!?!

Is anyone running a setup like mine?

[Tom Hartz]

Based on my Jeep experience this is what I see.

First tale a look at this. Gear Ratio from Tire Size

I am not sure what tire size your truck came with, so I guessed at 32" tall. Now running a 38" tire it looks like you should be running a 4.30 ratio.

Double check the numbers on the Currie Calculator.

Tom

[JSchuricht]

4.30 would put you close to stock.

[Tom Hartz]

Originally Posted by JSchuricht

4.30 would put you close to stock.

That is the same I was thinking. It should be good. Just remember even if you go with 4.30s you still have a much bigger tire to get rolling and stop. It will never feel like it did stock.

[GregsSD]

I run 4.30's with my 35's and it works great.
4.10 is not worth going to because it is not much change from 3.73, so go to at least 4.30, or even 4.56 if you really want some good towing power!

[z28gsxr]

Originally Posted by GregsSD

I run 4.30's with my 35's and it works great.
4.10 is not worth going to because it is not much change from 3.73, so go to at least 4.30, or even 4.56 if you really want some good towing power!

What kind of MPG do you get with the 4.30? I have a similar set up to the OP but have toyo All Terrains in a 37/14/18

As it is now i get roughly 14mpg. Mine doesn't struggle too bad in the uphills since i really don't tow more than like 7k but more power would not hurt. My truck only has a 4" turbo back and a k&n ram air intake as far as power mods go. Tuner is in the plans. Would it be best to get the tuner or the gearing first?

02 F250 7.3L 4x4

[GregsSD]

If you do the gears first, it will take alot of strain off of your tranny so it should last longer!

I get about 14 mpg, but I drive very little highway miles, it's all in town and backroads. Changing gears brought back about half the mileage that I lost by going to 35's.

[z28gsxr]

Originally Posted by GregsSD

If you do the gears first, it will take alot of strain off of your tranny so it should last longer!

I get about 14 mpg, but I drive very little highway miles, it's all in town and backroads. Changing gears brought back about half the mileage that I lost by going to 35's.

If you don't mind me asking, what did it cost for the gears and installation for both differentials?

[GregsSD]

Originally Posted by z28gsxr

If you don't mind me asking, what did it cost for the gears and installation for both differentials?

Gears, Bearings, and labor was around $1700-$1800