3.55 or 3.73 rearend
08-22-2011, 08:16 PM
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3.55 or 3.73 rearend
I am considering getting a 2012 f150 4x4 ecoboost with 5.5' bed. This will be my daily commuter 70 miles/day. Probably only tow a trailer 4k to 6k lbs a couple of times per year. Perhaps haul a kawasaki brute force atv a few times a year. Most terrain I drive is rolling, however when I tow the trailer it will be in the mountains. For those with the ecoboost that may tow similar weight, let me know what gear you have and if you are satisfied.
08-22-2011, 08:45 PM
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Can't help ya on the EB part (5.0 here), but I'd get a 3.73 if your going to tow anything upwards of 6k lbs. That's actually quite a bit of weight.
My 3.31's suck on factory 31's. If I had to tow anything right now it would not be a pretty site.
My 3.31's suck on factory 31's. If I had to tow anything right now it would not be a pretty site.
08-22-2011, 08:54 PM
#4
+1. I have the 3.55, but in retrospect, I'd prefer 3.73. The difference in fuel economy is marginal, but I suspect when towing there'd be a little less shifting and a bit better maintenance of speed on the slopes.
08-22-2011, 08:55 PM
#5
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I'm running 3.55. (with the 5.4). I pull a 6800lbs TT through the mountains in Eastern NC with no issue.
If you are only pulling a few times a year I would recommend the 3.55 simply due to gas/mileage as a Daily driver.
If you think you will move up in weight (towing/hauling) then I would consider the higher gearing.
Just my thoughts.
** Just read tailwaggers post... If the mileage really isnt that much different. I'd go 3.73 It give better future towing options..
If you are only pulling a few times a year I would recommend the 3.55 simply due to gas/mileage as a Daily driver.
If you think you will move up in weight (towing/hauling) then I would consider the higher gearing.
Just my thoughts.
** Just read tailwaggers post... If the mileage really isnt that much different. I'd go 3.73 It give better future towing options..
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08-22-2011, 09:18 PM
#9
3.73 is a few 100 rpm more at highway speed. I pull my 7500# TT into the mountains of east Tn, EB xlt 4x4 screw. No problem pulling with the 3:55's. You can't go wrong with either gear, at te weight you are talking 3:55's would be ok. I wouldn't let either gear be a deal breaker but I would make sure either one has a limited slip.
08-22-2011, 09:22 PM
#10
Senior Member
3.73 
More potential benefit obtained from the tow factor and also if you later put on a larger diameter tires; vs. any appreciable savings in gas, especially now that the trucks have 6-speed A/T's.
With the previous 4-speed A/T, the lower axle gearing could be more noticeable at the pump and at fwy. speeds.
More potential benefit obtained from the tow factor and also if you later put on a larger diameter tires; vs. any appreciable savings in gas, especially now that the trucks have 6-speed A/T's.
With the previous 4-speed A/T, the lower axle gearing could be more noticeable at the pump and at fwy. speeds.
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