2014 dodge diesels
I have been looking at these and I have to ask, why are the new trucks coming out with such high gear ratios? something like 3:42's or the likes. is it for gas mileage or is it because of all the tor...
Forum Discussion
It is for two related reasons with regard to gas engines. The higher gears produce better results with the EPA fuel economy testing which is done indoors on a dynometer and this fools many customers who still believe the numbers and the higher fictitious highway MPG helps the manufacturers meet the federally mandated fleet economy standards or CAFE.
When the most profitable products sold by the manufacturers are pickup trucks and at the same time these vehicles lower the fleet average for all vehicles sold in a given year, the manufacturers need to find a way out. They have use two tactics, one being the very tall gears which do not truly improve fuel economy with the truck empty and can actually reduce fuel economy when hauling or towing a heavy load as the engine spends more time outside its peak power band (which is why everyone is going to 8-speed transmissions).
The second tactic which is quite ingenuous is to get customers to buy diesel powered cars and trucks. The higher cost for the engine, for maintenance, and for fuel is shouldered 100% by the customers and the manufacturer gets a higher fleet average MPG.
Notice though that the higher gears also reduce towing capacity by 20-25 percent. A 2015 Chevy Silverado 1500 with the 6.2L gas V-8 and 3.73 gears is rated for towing over 17,000 lbs., or 5,000 lbs. more than the same truck with the same engine but with 3.23 gears.
With diesel trucks the engine produces peak torque at half the RPM's as gas engines so the gearing can be higher without much of a penalty in towing capacity. There is still a penalty and it is most apparent when you compare the towing capacity of the F-350 with that of the F-450 pickup truck with the latter truck's much lower rear end gearing.
When the most profitable products sold by the manufacturers are pickup trucks and at the same time these vehicles lower the fleet average for all vehicles sold in a given year, the manufacturers need to find a way out. They have use two tactics, one being the very tall gears which do not truly improve fuel economy with the truck empty and can actually reduce fuel economy when hauling or towing a heavy load as the engine spends more time outside its peak power band (which is why everyone is going to 8-speed transmissions).
The second tactic which is quite ingenuous is to get customers to buy diesel powered cars and trucks. The higher cost for the engine, for maintenance, and for fuel is shouldered 100% by the customers and the manufacturer gets a higher fleet average MPG.
Notice though that the higher gears also reduce towing capacity by 20-25 percent. A 2015 Chevy Silverado 1500 with the 6.2L gas V-8 and 3.73 gears is rated for towing over 17,000 lbs., or 5,000 lbs. more than the same truck with the same engine but with 3.23 gears.
With diesel trucks the engine produces peak torque at half the RPM's as gas engines so the gearing can be higher without much of a penalty in towing capacity. There is still a penalty and it is most apparent when you compare the towing capacity of the F-350 with that of the F-450 pickup truck with the latter truck's much lower rear end gearing.
