Why is it that for 2011 the maximum ratio is 3.55 with the diesel? Can't even get 3.73 like years past. Just wondering.

 

Because there's 735 lb.ft. of torque at 1600 RPM?

 

800 lb. ft. torque if you let ford reflash.

 

and with all the torque, they changed the tranny ratios to give more oomph off the line to compensate.

so the lower number ratio contributes to better mileage.

Sam

 

The new 6-speed Torqshift helps too.

 

As pointed out the 6R140 transmission is geared differently which also changed the axle ratio offerings making 3.73's unnecessary with the 6.7L.

Here are the final drive ratio calculations based on a 5R110W w/ 3.73's.

1st Gear - 11.60
2nd Gear - 8.28
3rd Gear - 5.78
4th Gear - 3.73
5th Gear - 2.65
Reverse - 10.74

Now here are the final drive ratio calculations based on the new 6R140 w/ 3.55's.

1st Gear - 14.11
2nd Gear - 8.23
3rd Gear - 5.38
4th Gear - 4.08
5th Gear - 3.05
6th Gear - 2.39
Reverse - 11.10

As you can see the 6R140 w/ 3.55's actually has a much deeper 1st gear once everything is calculated out. The 5R110W in this case would need somewhere between a 4.30 and a 4.88 axle ratio to equal the 1st gear pulling power of the 6R140 w/ 3.55's. Mind you that none of this takes in account for the additional power of the 6.7L.