3.31 or 3.55 rear end
#1
3.31 or 3.55 rear end
Test drove a 2012 EB SCREW 4X4 today with the 3.55 rear end.Thinking about a purchase in the near future and was curious if there is going to be much difference in the fuel mileage between the 3.31,3.55 and 3.73 rear?I will only be towing my ATV trailer. Salesman said there would be very little difference between them. I am looking for the best hwy fuel mileage possible..Thx.
#2
Inebriated 4 ur safety
Test drove a 2012 EB SCREW 4X4 today with the 3.55 rear end.Thinking about a purchase in the near future and was curious if there is going to be much difference in the fuel mileage between the 3.31,3.55 and 3.73 rear?I will only be towing my ATV trailer. Salesman said there would be very little difference between them. I am looking for the best hwy fuel mileage possible..Thx.
Edit: Sorry, I didn't fully read you post. If you are looking for best hiway fuel milage then I woild go with the 3.7L. It will easily tow atv's and give you better MPGs then the ECO plus it costs less.
Last edited by Al Kohalic; 01-30-2012 at 09:57 PM.
#4
I agree with Al Kohalic in that the ample torque available in the EB allows the taller 3.31, 3.55 gears to be quite effective in towing moderate loads. I have a 5.0 with 3.55's and it does just fine. So an EB with 3.31's should also be fine for the odd recreational heavy tow/load.
As far as the best for mileage. IMO, the 3.31. Trolling through the EB mileage threads (and there is a lot of them), many of the guys complaining of poor mileage have the 3.73's (and many with oversized tires, so gearing may not have as much impact). Seems like it shouldn't make a big difference, and in many instances it doesn't. But if you're a prospective buyer who honestly is using your truck for commuting more than towing/hauling, I would recommend the 3.31's. If you're pulling all the time, you're not going to go wrong with the 3.73's. The 3.55's are very capable and are there for those of us that want the compromise gear, cause we can't decide one way or the other.
There was an EB thread which also discussed how well the 3.15's pulled.
Lots of choices, but if you consider your needs well, you'll choose the right one.
As far as the best for mileage. IMO, the 3.31. Trolling through the EB mileage threads (and there is a lot of them), many of the guys complaining of poor mileage have the 3.73's (and many with oversized tires, so gearing may not have as much impact). Seems like it shouldn't make a big difference, and in many instances it doesn't. But if you're a prospective buyer who honestly is using your truck for commuting more than towing/hauling, I would recommend the 3.31's. If you're pulling all the time, you're not going to go wrong with the 3.73's. The 3.55's are very capable and are there for those of us that want the compromise gear, cause we can't decide one way or the other.
There was an EB thread which also discussed how well the 3.15's pulled.
Lots of choices, but if you consider your needs well, you'll choose the right one.
#5
Senior Member
3.31's are the standard SCREW 4X4 ratio, but it is an open rear end...no limited slip or electronic locking option. I would get the 3.55's to get an electronic locking rear end.
#6
There isn't enough difference between the two to matter MPG wise. You could go from 3.31 to 3.73 and still only maybe see about a 1 mpg difference. You have to have a pretty drastic change in gear ratios, maybe from the 3.15 to the 3.73 before you'd start having a really adverse effect on highway mileage.
Ford offers (and probably builds a lot of) the 3.15 and 3.31 configurations for CAFE, where .25-.5 mpg across one hundred thousand vehicles significantly affects their corporate average. Half a mile to the gallon to the average driver would require a couple years worth of driving to amount to much of a difference to your wallet.
Ford offers (and probably builds a lot of) the 3.15 and 3.31 configurations for CAFE, where .25-.5 mpg across one hundred thousand vehicles significantly affects their corporate average. Half a mile to the gallon to the average driver would require a couple years worth of driving to amount to much of a difference to your wallet.
#7
Senior Member
I don't think the gears make that much of a difference. If you never get on the throttle and one atv is all you will tow then I'd agree that the 3.7 is the best for you(which has a 3.73 gear but still gets the best mileage of any f-150). If you like knowing the power is there but never use it and want the ecoboost for that then get the 3.31. If you are buying the ecoboost because you love torque and power get the 3.73. If you're in the middle then the obvious choice is the 3.55.
On a side note, the 3.7 can be had on the screw but not with 4x4. The supercab with 4x4 can be had with the 3.7 though.
On a side note, the 3.7 can be had on the screw but not with 4x4. The supercab with 4x4 can be had with the 3.7 though.
Last edited by mechanicboy; 01-31-2012 at 01:33 AM.
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#9
I'll agree with the others - for your purposes, get the 3.7L. If you want *decent* gas mileage and still have plenty of power in reserve, get the EB.
I wanted a Lariat, and I honestly use my truck to commute in (probably 90% of my driving is commuting), so I got the EB with 3.55 LSD (don't need a locker, wanted LSD).
Now that I have my truck, I've hauled firewood, furniture and other detritus, and the EB has done it all without even having to breathe heavy! My MPGs are about dead on with the EPA ratings (15/21 city/hwy) now that I've got 4,000 miles on her and the engine is somewhat broken in.
Just my $.02 - hope it helps!
-John
I wanted a Lariat, and I honestly use my truck to commute in (probably 90% of my driving is commuting), so I got the EB with 3.55 LSD (don't need a locker, wanted LSD).
Now that I have my truck, I've hauled firewood, furniture and other detritus, and the EB has done it all without even having to breathe heavy! My MPGs are about dead on with the EPA ratings (15/21 city/hwy) now that I've got 4,000 miles on her and the engine is somewhat broken in.
Just my $.02 - hope it helps!
-John
#10
At cruise, the turbos will only produce a negligible amount of boost regardless of gear ratio. Boost is not only dependent upon RPM, but throttle opening and engine load. You can run a turbocharged engine with no load at 5000 rpm and produce very little boost.