differential change
Soon I hope to change the differentials on my 2004 f350 V10 4X4. It came stock with 3.73 gearing. Now we are pulling a 5er that weighs about 11,000lbs. This setup pulls the 5er just fine here in flat-...
Forum Discussion
klr650goldwing wrote:
Bryan,
Did you MPG go up or down while towing after you switched to 4.56? Have you pulled that rig over the Rockies?
Thanks for your input everyone. This is very helpful information.
Solo fuel economy went from 15.5 MPG hwy to 14. Towing (~12,000 pounds) went from 6.5 to 8. Since I tow more than I don't, it was a net gain for me! For somebody who only tows occasionally, it may not make as much sense.
I tow over the Rockies at least once a year, load weight averages about 15,000 pounds but has been as high as 18,000 (trailer weight plus passengers and cargo in van), which puts my typical combined weight around 22,000 pounds but it can hit 25,000.
In the mountains, having 4.56 gears is a HUGE improvement, and that's why Ford rates their powertrains so much higher with those gears (22,000 with 4.56 vs 15,0000 with 3.73). With 3.73 gears, I couldn't even stay in overdive with a headwind, and gentle grades would drop me into 2nd. Pulling a 7% grade used to require 1st gear when I was pulling 15,000 pounds! That meant top speed was only about 35 MPH. Now I can pull the same hill and do 60 or better because I can stay in 2nd.
