Larger Rear End parts

[CBlack]

Not that I'm looking but was curious as to the benefits/disadvantages are of the 4. 88, 5. 13 etc and higher gearing is in rear ends.



I know a lot of sled pullers use them. For everyday use they would be a drag on fuel economy I would imagine.

 

[Deleted member 995608]

Cons,



#1. Fuel economy



#2. Reduced top end speed



#3. High RPM's at freeway speeds



Pros,



#1. Could pull the A $ $ out of a mule.

 

[fox]

Changes in gearing is one way to change torque at the tires. With the Cummins another way is to add fuel!!! But, keep the engine running at its peak power or efficiency. Usually this is at 1700-1900 for best MPG and 2200-2400 for best pulling at highway speeds. Gearing and tire diameter must go together.

Many owners of these trucks want 3. 73 to 3. 54. Some even want 3. 25!!



It is all about what you do with it.

 

[HBarlow]

Lower geared (higher numerical ratio) differentials will allow a relatively small and low power engine to start and pull extremely heavy loads. It can be done at the expense of poor fuel mileage, lost top speed, high rpm at low speeds, and intolerable cab noise as others have already stated.

Big trucks with multiple speed transmissions can overcome the drawbacks.

Edit: After writing the above it occurred to me that a better answer can be offered in two words . . . torque multiplication.

 

[Schumacher]

Lower gears have smaller pinions and less gear tooth contact.