Pick-up Truck Rear End

wilke3169 · 08-17-2005, 06:07 PM

I recently bought a 2005 Chevrolet work truck. I didnt need any options but the one I got came with a heavier suspension and the rear end is a 3.73 instead of the standard 3.23. Would someone interpret this for me? May be a dumb question but I just don't know what the numbers mean.

Thanks,
Kevin

yellowline · 08-17-2005, 06:17 PM

Final drive gear ratios. Ratio, in this case, is 3.73:1...it compares the revolutions of two things...ultimately, I *think* they measure transmission output shaft against wheel rotation.

The higher gear ratio in your truck multiplies torque a little more. That's why many high-number gear ratios like 4.11 are known as "stump-pullers." Higher numbers in a P-car would benefit acceleration, but lower top speed, since it affects how fast your wheels are turning.

turbo6bar · 08-17-2005, 06:29 PM

Higher rear ratio is going to make your truck a good towing rig. Unloaded, you will have lower fuel mileage, but you can pull a trailer with ease.

928ram · 08-18-2005, 05:09 AM

As yellowline stated, it's a ratio of how many revolutions the pinion gear/driveshaft must make to get a full revolution of the ring gear/axles/wheels; all else being equal the higher the ratio, the higher the engine RPM at a given speed.

That is if all else is equal. Did the package on your truck include bigger wheels and/or tires? Larger diameter tires will have the same effect is a higher (lower numerically) gear ratio. As an example; I have a Dodge with the factory installed 20" wheels and tires which runs a (low) 3.93:1 ratio, the same truck with the 17" wheel package runs a (higher) 3.54:1 ratio but actually turns slightly more RPM at a given speed because of the difference in tire diameter.

wilke3169 · 08-18-2005, 05:59 AM

Thanks guys.
928 Ram, It has the standard 17" tires. The reason I asked actually was' I went on a 2000 mile trip last week and averaged 19 mpg. Nothing to brag about but I just got rid of a 2001 truck that was much like this one and the mileage is very similar. I didnt choose the rearend it just happened to come on the truck the dealer found for me.
Thanks Again,
Kevin

David · David's Garage

I've got the 3.73 in my 2001 silverado instead of the stock gearing. It may get a 1 mpg less mileage but I like the lower gear for pulling a trailer and getting away from stop lights.