4.10 rear in new Ford F350
A lot of leftovers have the 4.10 rear any one know if there would be a big difference in MPG towing or would it be negligible..?
Forum Discussion
Lynnmor wrote:Me Again wrote:Lynnmor wrote:Me Again wrote:
. What you think you gain with the lower diff gears in negated by the steeper OD ratio. Think final gear ratio!
Keep in mind that the transmission is worked harder with higher diff gears.
You multiply the top gear ratio times the diff gear ratio, and the result is always more torque with the lower rear gears. Add to that, each gear change is less of a difference in road speed, keeping the engine at a better RPM.
That basically applies in first gear to get a load moving.
Out on highway one is in 5th and the other in 6th at the same speed. You are dismissing a taller 6th gear od ratio.
I am not dismissing anything, the multiplier (rear gear ratio) is the same in every gear.
So the 4.10 will put 15% more torque to the axle in every gear but it does not put more torque to the rear axle at every speed. So for instance at 60 mph on a 6% grade with 16k lbs in tow and foot to the floor the 6r140 will be in 4th with 3.55 gears and in 5th with 4.10 gears. The 3.55 will be putting 5% more torque to the rear axle. If that trailer is increased to a 22,000 lb 5ver the trucks will be slowed to 50 mph on a 6% grade. Both trucks will be in 4th gear. The 4.10 equipped truck will be running at 2518 rpm and the 3.55 equipped truck at 2180. The 4.10 will be putting 13% more torque to the rear axle. Bottom line is that 4.10s are advantageous for heavier trailers but for a 16k fiver you're better off with 3.55s.
