i assume higher is better?
Howdy. Given two identical tow vehicles but with different gear ratios where one has a higher one than the other how does that factor into the towing capabilities issue?
Forum Discussion
It would help a LOT to know the tow vehicle, engine, and such. Model year, if you know if it has a 2001 4 speed or a 2015 8 speed, it makes a HUGE difference !
Diesel actually will run better at lower RPM's than a gas engine. So 3.73:1 might be ideal with a diesel, while 4.10:1 might be good for a gas engine, and 4 speed auto.
My 1975 F-350 had a 3.73:1 ratio and 460" engine, so a lot of power. By running the 3.73:1 ratio, I did not turn the engine a lot faster than required to keep the load moving at 60 MPH.
I have a van now, with a V10, 10,000 GVW (14,050 GVWR) and it turns much faster than it need to for the loads on it. Gas mileage at 65 MPH is really bad, but at a slower RPM, such as going 55, it gets better mileage. It is a 2001 Shuttle bus, with 4.68:1 rear axle ratio.. Given that the V10 has lots of torque, I would be much happier with 3.73:1 ratio. Yet the 4.68 was selected because most E-450's have a 11' tall body that is 8' wide (80 square feet of air to push out of the way) and are typically much closer to 13,500 pounds GVW. I only have a 4 speed, while newer E-450's would have a 5 speed, and improved MPG.
So lets say that you have a 5.4L V8, 7,000 pound trailer, and 4 speed auto. With a 3.73:1 ratio, at 65 MPH, your truck would be running around 2,400 RPM. If that is changed to a 4.10:1 rear axle, then around 2,600 RPM. This will cause the engine to be able to make more HP at the higher RPM band, while also consuming more fuel. . So 'higher' is not better if you are the one buying the gas.
Yet if you take this to the extreme, and say have a F-150 with 3.08:1 rear axle, you might be turning 1,800 RPM in overdrive at 65 MPH, and constantly needing to downshift to drive to bring RPM back up to 3,000 to gain some speed again and again. If the transmission is 'hunting' from overdrive to drive and back over and over again, it is best to lock out overdrive, to prevent all that extra shifting for a while, until headwinds are less, you start downhill, or something changes.. .
Good luck,
Fred.
Diesel actually will run better at lower RPM's than a gas engine. So 3.73:1 might be ideal with a diesel, while 4.10:1 might be good for a gas engine, and 4 speed auto.
My 1975 F-350 had a 3.73:1 ratio and 460" engine, so a lot of power. By running the 3.73:1 ratio, I did not turn the engine a lot faster than required to keep the load moving at 60 MPH.
I have a van now, with a V10, 10,000 GVW (14,050 GVWR) and it turns much faster than it need to for the loads on it. Gas mileage at 65 MPH is really bad, but at a slower RPM, such as going 55, it gets better mileage. It is a 2001 Shuttle bus, with 4.68:1 rear axle ratio.. Given that the V10 has lots of torque, I would be much happier with 3.73:1 ratio. Yet the 4.68 was selected because most E-450's have a 11' tall body that is 8' wide (80 square feet of air to push out of the way) and are typically much closer to 13,500 pounds GVW. I only have a 4 speed, while newer E-450's would have a 5 speed, and improved MPG.
So lets say that you have a 5.4L V8, 7,000 pound trailer, and 4 speed auto. With a 3.73:1 ratio, at 65 MPH, your truck would be running around 2,400 RPM. If that is changed to a 4.10:1 rear axle, then around 2,600 RPM. This will cause the engine to be able to make more HP at the higher RPM band, while also consuming more fuel. . So 'higher' is not better if you are the one buying the gas.
Yet if you take this to the extreme, and say have a F-150 with 3.08:1 rear axle, you might be turning 1,800 RPM in overdrive at 65 MPH, and constantly needing to downshift to drive to bring RPM back up to 3,000 to gain some speed again and again. If the transmission is 'hunting' from overdrive to drive and back over and over again, it is best to lock out overdrive, to prevent all that extra shifting for a while, until headwinds are less, you start downhill, or something changes.. .
Good luck,
Fred.
