F250 6.2 gas Towing heavy with 3.73 rear ??

double post

Follow up...

Several trips now and including the last one up I55 with a few hills, I can report happy with no issues with my combo. (trailer weighs 12,000 lb loaded)

I do feel using the transmission manual mode helps with my towing experience, using 4th and 5th in the hills kept the speed easly above 60 mph. If I let the auto do the work it would drop to 3rd when not really needed.

Now the steepest grade I faced so far, was the I10 bridge going over the Mississippi in Baton Rouge, Pulled up the bridge in 3rd with plenty of power left at 60 mph.

Off the line, 1st is plenty low enough with the 3.73 rear due to the low first gear in the 6-speed auto.

Top speed 65 mph, but can easly go over 70 mph to pass when needed, even when locked in 5th manual without down shifting.

Michigan to Florida, 65 MPH on any hill.

Now there is the kinda 6.2 I need. :h

My ole 6.2 with 4.30 diffy towing the 10.5K fifth wheel up Saluda Hill (long 6% grade heading north In NC). Now I do not climb hills with foot on the floor, but I topped that grade at 50 mph. I felt comfortable with the R meter setting on 3700. Don't get me wrong, I am happier than a pig in you know what with the F250 gasser.

Denny & Jami wrote:

Learjet wrote:
having this discussion on another forum..

about 3:73 vs. 4:30 rear gears for the Modern Super Duty Gas engines...this is a 6 speed tranny with 5 and 6 being over-drive gears.

"But... once operating in a transmission over-drive gear,either 5 or 6, the torque is not magically produce by the 4:30 rear gears...right?

example:
3:73 gears, 5th (1st over drive from transmission) engine operating at 2200 rpm = X torque at wheels

4:30 gears, 6th (2nd over drive from transmission) engine operating at 2200 rpm = X torque at wheels.

in this case X should be equal? "

What say you?

The rear end gears are the last torque multiplier so lower gears will give you more mechanical advantage through all the gears.

Simple example you need to torque a bolt to 1000 you use a 10 to 1 multiplier so you only have to exert 100 ft lbs to get that torque. If you go to a 5 to 1 multiplier you would need 200 ft lbs to gain the same same torque.

Denny

I get that, but I think that you are reducing the torque from the engine at the drive shaft with the 2nd over-drive gear, so for the same engine speed (rpm) and the moving speed (MPH) if the over all gearing is the same as in my example, then?

I know it is not perfectly even in the Ford with the different rear gear and 5 to 6 gear...but just for discussion.

Higher numerical differential gearing will put transmission gearing closer together.

dodge guy wrote:
The rear axle gears will effectively change the ratio of each gear in the transmission. Lower axle gears will make each gear more effective in moving a given load.

Yes but with 6 gears(or 8 or 10 in some cases) to choose from is the difference in rear end ratios really that black and white as with the old 3 speeds?

The rear axle gears will effectively change the ratio of each gear in the transmission. Lower axle gears will make each gear more effective in moving a given load.

Learjet wrote:
having this discussion on another forum..

about 3:73 vs. 4:30 rear gears for the Modern Super Duty Gas engines...this is a 6 speed tranny with 5 and 6 being over-drive gears.

"But... once operating in a transmission over-drive gear,either 5 or 6, the torque is not magically produce by the 4:30 rear gears...right?

example:
3:73 gears, 5th (1st over drive from transmission) engine operating at 2200 rpm = X torque at wheels

4:30 gears, 6th (2nd over drive from transmission) engine operating at 2200 rpm = X torque at wheels.

in this case X should be equal? "

What say you?

The rear end gears are the last torque multiplier so lower gears will give you more mechanical advantage through all the gears.

Simple example you need to torque a bolt to 1000 you use a 10 to 1 multiplier so you only have to exert 100 ft lbs to get that torque. If you go to a 5 to 1 multiplier you would need 200 ft lbs to gain the same same torque.

Denny

Learjet wrote:
having this discussion on another forum..

about 3:73 vs. 4:30 rear gears for the Modern Super Duty Gas engines...this is a 6 speed tranny with 5 and 6 being over-drive gears.

"But... once operating in a transmission over-drive gear,either 5 or 6, the torque is not magically produce by the 4:30 rear gears...right?

example:
3:73 gears, 5th (1st over drive from transmission) engine operating at 2200 rpm = X torque at wheels

4:30 gears, 6th (2nd over drive from transmission) engine operating at 2200 rpm = X torque at wheels.

in this case X should be equal? "

What say you?

5th is 0.86:1 so 3.73 in 5th is 3.21:1
6th is 0.67:1 so 4.30 in 6th is 2.89:1

The 3.73 in 5th will put more torque to the wheels at 2200 rpm, but it will also be travelling slower.

having this discussion on another forum..

about 3:73 vs. 4:30 rear gears for the Modern Super Duty Gas engines...this is a 6 speed tranny with 5 and 6 being over-drive gears.

"But... once operating in a transmission over-drive gear,either 5 or 6, the torque is not magically produce by the 4:30 rear gears...right?

example:
3:73 gears, 5th (1st over drive from transmission) engine operating at 2200 rpm = X torque at wheels

4:30 gears, 6th (2nd over drive from transmission) engine operating at 2200 rpm = X torque at wheels.

in this case X should be equal? "

What say you?