hey guys i have a question about gearing in the diffs. i have an 03 hemi qc 4X4 and i was wondering how do the gears work like whats the difference between 3:92 gears and 4:56 gears? what do the numbers mean? how do i know what gears i need? how do i tell what gears i have? stuff like that any help would be great thanks.

 

The gear ratio of the differential gearbox. The differential gearbox distributes the engine's power (via the transmission input shaft or propellor shaft) to the wheels. The axle ratio of the differential reduces the revolutions of the transmission input shaft before it reaches the wheels. Typical automotive axle ratios are in the range of 2.71 up to 4.31. The higher the ratio, the faster the engine will rev at a particular vehicle speed.

I should mention that I cut & pasted this definition, I ain't that smart...

For what gears are ideal for your particular setup:
http://www.4wheelparts.com/CT13.aspx#

 

Correct. 4:56 means for every 360 degree rotation of the ring gear, thepinion gear (driveshaft) rotates (spins) 4.56 times.

Same 360 degree spin for a 2:71 ratio, and the drive shaftspins 2.71 times.

The 4:56 ratio would give you tons of pulling power, but a lower top speed. The 2:71 ratio would be terrible for pulling out, (low end) but give you a higher top speed.

You should be able to find out your gear ratiothe tag on the rear diff cover, attached to one of the bolts, OR look on the sticker inside your glovebox.

 

if you miraculously still have the factory lables on your axle tubes ( i had them on mine) they say exactly what gear you have.

btw i just went through a swap.the front is an 8" and the rear is the common 9.25". make sure whoever you get gears from that they are giving you 8" for the front.