Busted rear diff dodge 2500

[dodge man]

You have it correct, the higher number is better for towing and the lower number is for better fuel mileage.

 

[sportscarclinic]

As a rule of thumb, numerically higher lower gears will provide better fuel economy, but the selection of the "ideal" ratio depends on the torque curve of the engine, transmission final drive ratio (overdrive or not), anticipated load, and road speed while towing, among other things. In other words, it's possible to underdrive the engine by selecting too high a final drive ratio seeking better economy. Doing so might cause the engine to lug at cruising speed, increasing the possibility of both detonation and repetitive downshift-upshifting. You can also play with tire and wheel diameter to fine tune the rpms at cruise.

 

[Too many Kubotas]

As a rule of thumb numerically higher gears will provide better fuel economy...

Surely you meant numerically lower...or higher gears.

 

[sportscarclinic]

You are correct, my error. Even after 40+ years of mechanic'in I still jumble this one occasionally.

 

[sd455dan]

Ford F350 SuperDuty and don’t look back…..

 

[Too many Kubotas]

I've never had enough tools or patience to own a Furd.
Have worked on enough of them, though.

 

[ruffdog]

Sometimes modern trucks will skimp on the size of the diff carrier to keep costs down and mileage up, at the cost of reliability. With a small carrier and a high (numerically)gear ratio (4:11 eg), the pinion diameter gets quite small and the contact patch is also small. You need a bigger carrier so your ring gear can be bigger and also your pinion diameter. But, they cost more and take more HP to turn those bigger bearings etc.

Edit: clarification.

 

[Too many Kubotas]

Sometimes modern trucks will skimp on the size of the diff carrier to keep costs down and mileage up, at the cost of reliability. With a small carrier and a high gear ratio (4:11 eg), the pinion diameter gets quite small and the contact patch is also small. You need a bigger carrier so your ring gear can be bigger and also your pinion diameter. But, they cost more and take more HP to turn those bigger bearings etc.

Surely you meant "a low gear ratio", right?

 

[Snobdds]

Ford F350 SuperDuty and don’t look back…..

The only correct answer...

 

[Hay Dude]

The only correct answer...

…..is Cummins.