Ford super duty 3.31 rear end. Will it be a big mistake. ?
Pulling a 37 foot Cedar creek with a f350. Diesel. Would the 3.31 rear end work or should I get the 3.55?
Forum Discussion
3.31 and 3.55 are both good ratios for towing anything a SRW is capable of towing. Maybe a good way to compare the two is like this:
With the 3.31 ratio the truck will spend a little more time in each gear than a 3.55. (The travel speed range of each gear is about 7% more for each gear with a 3.31 final drive) This means there is apt to be times when it is desirable to lock out 10th gear with the 3.31 gears (maybe towing into a stiff wind). When operated as a 9 speed the 3.31 will do less shifting than the 3.55 equipped truck. When towing light or running empty the 3.31 gears will provide better fuel economy. I think even if I was planning on 90% of my truck’s use to be towing a heavy RV I’d have ordered 3.31 gears and be prepared to lock out 10th gear under certain conditions.
With the 3.31 ratio the truck will spend a little more time in each gear than a 3.55. (The travel speed range of each gear is about 7% more for each gear with a 3.31 final drive) This means there is apt to be times when it is desirable to lock out 10th gear with the 3.31 gears (maybe towing into a stiff wind). When operated as a 9 speed the 3.31 will do less shifting than the 3.55 equipped truck. When towing light or running empty the 3.31 gears will provide better fuel economy. I think even if I was planning on 90% of my truck’s use to be towing a heavy RV I’d have ordered 3.31 gears and be prepared to lock out 10th gear under certain conditions.
