Did you know re: Dodge Ram?
On Dodge.com, in their towing guide, it specifically states that Dodge does not recommend towing a trailer with the 3.21 axle ratio. http://www.dodge.com/towing/D/basics/terms_conditions.html Ch...
Forum Discussion
tempforce wrote:
the 3.21 rear gear builds up more heat than the 3.48-3.73 gear ratios.
the higher number ratios gears turn more. they have a lower load ratio per sq inch on the gears when towing heavy...
Not really, your parasitic loss is actually higher with a numerically higher (shorter) pinion & ring ratio. This is why NASCARs run taller gears and modern semi trucks run high OD transmissions with 2.xx rears.
The closer in size of the ring and pinion, the higher the meshing efficiency. Yes, the lateral & radial load on the pinion is higher, but that is compensated by the slower turning ring gear. Your parasitic loss is force * velocity, so that part evens out in the end.
Remember, the transmission & diff works as a team. An 8 speed ZF would be inefficient with a 3.92.
Ask yourself, with RAM's old 5/6 speed, would you pick a 6.14 rear end? That's the equivalent in 8spd+3.92
