My buddy has an 06 Cummins, 6 spd, 4x4, with around 6K on it. Just recenly found out it's got 4:10 gears. This truck is never used for towing, and is mainly just a town truck. What would be the easiest and cheapest way to knock the RPM's down? At 70mph he's running around 2500rpm. That sucks for driving interstate speeds of 75 around here. I've looked at 2-speed slitters and they're about $3,300. How much would it be to change the front and rear differencial to 3:73 or 3:55 or one of those? Thanks. J.W.

 

Smallertires

Ex. xxx/85/17 = 4.10's swap them for xxx/75/17 = 3.61 gear ratio

http://www.bncoffroad.com/tire_gear_cal.html

 

Nope! He would need larger tires to get a numerically lower gear ratio

(31.5 / 33) x 4.10 = 3.91

(31.5 / 35) x 4.10 = 3.69

He'd need 35's to get down to where he wants. That would be lost completely in the extra fuel he'd be burning.

A gear swap for a 4x is gonna run around $1000 - $1800, depending on the labor rates in your area.

 

Yea, you're right. You see where my message says "edit" that's because I originally had get larger tires. I alway get that equation confused. I thought I was right the second time.

 

See what happens when you start thinking[8D]

[sm=icon_beat.gif]........................[&:]

 

The calculator in this link is no good then, it says that if you have 4.10's and go from 33's to 35's your gear ratio will be 4.34. So it's backwards.

 

A gear swap kinda looks like the next best bet then. I know you can get 3.73's cause that's what mine has, but what about getting lower. Say 3.50, 3.60's

 

tone down some of the claims made
and this article is worth reading:

http://dieseltruckworld.tenmagazines...e&aid=2798

 

I have the 4:10 in mine and to be honest its not all that bad. I regularly drive 75-80 on the highway with the cruise set and knock down 18-19 mpghand calculated. Not horrible ...

 

ahem. . .if he's got a stick he's got 3.73's.

4.10's are only offered with the auto, what you are seeing is the higher final drive ratio of the G56