CumminsDriver wrote:
4x4ord wrote:
4x4ord wrote:
Viperpoker wrote:
CumminsDriver wrote:
I haven't seen it mentioned yet, but transmission gear ratios along with only having the 3.73 gears hurts the GM for the big tow ratings. The Allison has a 3.23 first gear compared to the Aisin with 3.72 I believe and the Fords 3.93 first gear. Throw in the 4.10 gears for the Ram and Ford and you have much better take off capability compared to the GM.
Rich
i think this answers my question as to why gm tow ratings are so much lower. combination of no 4:10 and the allison trans. that all makes sense.
I agree, it seems very reasonable until you think about the numbers. In 2016 the GM HD3500 dually was rated for pulling up to 23200 lb with an engine that made 765 lb ft of torque. In 2017 they increased the torque to 910 lb ft and yet the new 3500HD is still only rated for pulling 23300 lbs. You'd think if the limiting factor was putting torque to the rear wheels in low gear the new engine would have made an improvement in the tow rating. 910/765 x 23200 = 27600.
Don't forget torque management. None of the engines are putting out full engine torque in first gear.
I believe the main application of torque management is to limit fuel during shift points to avoid damage to the clutches. It makes absolutely no sense to limit torque at the engine and multiply it in the transmission if the concern is torque on the drive shaft or rear axles. With my Ford I have had very heavy loads on my tandem dually gooseneck and had to feed it full throttle to get moving when off road in soft ground. Often I will shift the transfer case to low range in those circumstances and the truck will move the load easily. So obviously the rear axle, driveshaft and output shaft of the transfer case have no problem handling far more torque than what is being delivered in low gear high range ..... what parts do you think torque management is protecting?
