just a little more power
Hi all, We have an 2015, F350, 6.2,srw, crew cab, 4x4. We tow a Flagstaff 2020 529RLKS, uvw 9631 lbs. We live in California, so just about anywhere you go, you go over a hill, mountain. I would like ...
Forum Discussion
parker.rowe wrote:
I'm not sure why people think the rear gear ratio only changes rpm/mph.
It increases torque multiplication to the rear wheels. It will tow more easily in all gears. It may allow towing one gear higher than usual
If the truck is in fact a 3.73 truck, it will make a difference going to 4.30's. Ford didn't offer that option for fun.
Yes, it will increase cruise RPM in 6th by 2-300 rpm. Might loose 1mpg unloaded. But as Fish stated you may gain mpg towing.
With all else equal, you are correct...but else isn't equal.
Who cares if you are towing one gear higher than usual if the engine is running at the same RPM/MPH? (assuming you don't exceed the ratings) The engine doesn't know if the torque multiplication is happening in the transmission or in the rear end.
Back in the old day's of 3 speed transmissions, there was so much difference between gear ratios, it was common when dropping down a gear to overshoot the ideal RPM/MPH for the engine and load. This left the engine racing while lightly loaded (not ideal for efficiency or power generation). A different rear end ratio could sometimes help align the RPM/MPH desired with the engine's ideal RPM.
With modern transmissions that have lots of gears to pick from, if you need torque multiplication, it can just drop down a gear (assuming you aren't already in 1st gear and struggling) and since the gear ratios are relatively close, it should be able to find a gear that keeps the engine in it's happy RPM range.
Ford offers the 4.30 for when you are pushing the truck so hard, it does struggle to get beyond 1st gear (or for old timers who automatically think you need a 4.X rear end if you tow?). That doesn't seem to be the OP's concerns.
