Changing differential gears
WWould like to hear from those that have actually changed their rear-end ratios. Did you get any improvement? Was it worth it? Any pitfalls?
Forum Discussion
mtofell1 wrote:ol' yeller wrote:
Gas mileage didn't improve or degrade enough to notice.
I think this is what a lot of people need to read and reread. Whenever gearing discussions come up, the whole MPG thing is way overstated. Unless you are doing a very drastic change it likely won't be noticed.
Just to throw some real numbers out there.
With my 3.73 to 4.30 swap I gained .5 mpg towing and the same amount in city/hwy driving. I did lose that .5 mpg on the hwy with no trailer, but when you go from 14.8 to 14.3 its not a dealer breaker! and the X very rarely doesn't have the trailer attached to it.
And when I added the tuner from 5 star tuning a year later it really woke up the V-10! it shifted the way it should have from the factory! Fords shift strategy leaves a lot to be desired. and here again because of its ability to hold each gear longer when upshifting (which uses the available power more efficiently, meaning no short shifting) and its ability to hold OD a bit longer reducing downshifting, I gained another .3 mpg. yes these are real world numbers and not something I dreamed up.
And every time I see the RPM drop on the 1-2 and 2-3 shift it makes me sick, that's how terrible it is at transferring power!
One final thing I did was add an air deflector to push the air up and over the trailer. and this again gave me another .4-.5 mpg. So When I started out I was getting around 6.3 with my V-10. I can now get 7.5-7.7 all day. if its not windy and I slow down I get 8, although that is very rare that's its not practical to go by.
Now with all that said. the newer 6,8,9 and 10 speed transmission are very efficient at transferring power. so unless your towing really heavy you are not going to see much of a change.
