How critical is axle ratio?
In the modern day of 10 speed automatics, how necessary are 'towing' gears? By 'towing' I mean anything over 4.xx. These new transmissions have such low first gears compared to just a decade ago, is ...
Forum Discussion
Lynnmor wrote:valhalla360 wrote:
If you are within the trucks ratings, talk of increased stress is a red herring.
The manufacturers have designed to account for it.
Is that why all trucks last forever? :D
Yeah! Like the current half-tons will last the same as an HD with the 14k tow ratings they have these days. Right...
valhalla360 wrote:
If you are within the trucks ratings, talk of increased stress is a red herring.
The manufacturers have designed to account for it.
Not really. Even Dana-Spicer, one of the largest driveline manufacturers in the world, states that the life expectancy of driveline components decreases with lower axle ratios.
The above images are from research done by Dana-Spicer on their driveline products in the heavy-duty truck market where trucks typically cruise at around 1,400 rpm. Keep in mind that this is using their product well below the truck's ratings and only using 200 hp. Eaton and Meritor did the same with their transmissions and clutches, but I do not have the link.
Many times, speccing a lower axle ratio to save money on fuel economy is negated by added maintenance/replacement cost of the parts that this lower axle ratio effect. If one does not tow close to their ratings that often then it is probably better to get a lower axle ratio. However, if you are towing closer to your max ratings on a regular basis then the higher gear option is probably the best way to go for longer component life.
