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
Huntindog wrote:
The 3.21 is a poor choice for towing. Lots of people say that all you gotta do is run in a lower tranny gear to make up for it.
Not really. Where the multiplication takes place matters to the overall performance and longevity of the driveline. Even if you have really low first gear for starting it rolling, the U joints are getting no help from that.
U-joints have to be rated for the maximum transmission torque output (plus a factor of safety). That max torque is solely dependent on engine torque x converter multiplication x 1st gear ratio.
In fact, I can go a step further and say within reason, they also have to withstand the torque multiplication of a transfer case as well, in the extreme case the front axle has no grip and the rear as all.
Therefore, to say that the u-joints can be hurt simply by the load resistance of 3.92 vs 3.21 gears is really stretching it. Take away the u-joint and driveshafts, no other thing stands in the way between the transmission and axle shafts.
With the 8 speed ZF, a 3.21 truck is equivalent of old truck with 5.03 gears. I would NOT (and did not) pick a 3.92 unless I'm full time towing, which is rare on a 1/2 ton.
