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Discussion Starter · #1 ·
Thought I had every detail of my truck correct. SuperCrew, 4x4, shortbed, locking dif, with the tow package. I thought because of the towing package it would have been at least 3.55(s). Anyway, I have read several threads about 3.55(s) and 3.73(s). Seems every states the 3.73(s) have quicker starts, better city mpg, tows better, doesn't downshift when pulling, and one mpg less on the hwy. Well what does the 3.31(s) have to offer?

When I'm in the turbos my truck feels pretty good. It just seems like it takes a second to get going. Again, once I get going it feels pretty good.

Anyone with 3.31(s) have buyers remorse?

Anyone have positives about the 3.31?

Thanks for the input.
 

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Seriously, unless your trying to haul the Empire State Building....3.31 rear gears with the ecoboost is plenty. I have them and have never regretted having them. I haul cars everyday of the week without a problem.
 
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Thought I had every detail of my truck correct. SuperCrew, 4x4, shortbed, locking dif, with the tow package. I thought because of the towing package it would have been at least 3.55(s). Anyway, I have read several threads about 3.55(s) and 3.73(s). Seems every states the 3.73(s) have quicker starts, better city mpg, tows better, doesn't downshift when pulling, and one mpg less on the hwy. Well what does the 3.31(s) have to offer?

When I'm in the turbos my truck feels pretty good. It just seems like it takes a second to get going. Again, once I get going it feels pretty good.

Anyone with 3.31(s) have buyers remorse?

Anyone have positives about the 3.31?

Thanks for the input.
I factory ordered the 3:31's as 90% of the trucks on the lot are equipped with 3.55 or 3.73 gears, I have a 50 mile return daily commute . At 60 mph the rpm's are 1500. I tow a 8000 lb travel trailer with a quad in the box ocassionaly and it has plenty of pulling power. I wish I ordered the 3.15's as the torque curve of the EcoBeast is steady across the rpm range. I get 600 miles per tank of gas and my truck has 3000 miles on it
 

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There's about a 500 lb trailer difference between the 3.31 and 3.73 gears. Will the lower gears pull harder? Yes. Will it matter in the general driving experience? IMHO, no. If 95 percent of your driving is with no trailer, the 3.31s make sense. They'll still pull 9500lbs.

Sent from my SGH-I747M using Tapatalk 2
 

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If your new to boosted motors the "takes a second to get going" has more to do with the lag in builing boost than the rear gear ratio. A. Oosted motor needs rpm to build boost aka power. So when you floor it from a stop there is a slight hesitation before the power "hits" this is do to the turbos having to spool up and build boost. Not as big an issue on these ecoboosts as it is in a typical turbo car as we have a smaller one feeding the larger one which eliminates alot of the lag. Watch a turbo drag car sone time youll notice that before the light goes green they sit on the line and bring the rpms up on the motor to "build boost" before launch. Other wise the car would nose over until the engine built rpms. You would notice a small difference in 331 vs 355 geared truck but not much.
 

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If your new to boosted motors the "takes a second to get going" has more to do with the lag in builing boost than the rear gear ratio. A. Oosted motor needs rpm to build boost aka power. So when you floor it from a stop there is a slight hesitation before the power "hits" this is do to the turbos having to spool up and build boost. Not as big an issue on these ecoboosts as it is in a typical turbo car as we have a smaller one feeding the larger one which eliminates alot of the lag. Watch a turbo drag car sone time youll notice that before the light goes green they sit on the line and bring the rpms up on the motor to "build boost" before launch. Other wise the car would nose over until the engine built rpms. You would notice a small difference in 331 vs 355 geared truck but not much.
The turbos are a mirror image of each other and run in parallel not in sequence.

My turbo focus didn't build full boost until 4500-5000 rpm depending on how much I was running. So I don't understand what all the fuss is about lag when full boostcomes in these trucks at 1750 rpm! Personally I would have liked them to spool alittle later, say 2000 rpm so you could drive without getign into them as much. I guess then my truck wouldn't pull a 6k lb travel trailer in od at 55 mph.
 

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Just found out mine has the 3.31 gears. My first truck don't know any different.
 
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Discussion Starter · #12 ·
Well, I haven't had any issues with my truck. So, I would state everything is fine. Again, I have just read a lot of threads w/person(s) talking about the 3.73 gears and how the mpg is really no different, yet they get better city mileage and have more torque w/one mile per gallon better on the highway. Well, hell, that sounds like a cherry of a deal. Just wondering what is my advantage to having the 3.31(s). Thanks guys for the good insight.

Thanks again,

Al
 

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I dont see how anyone is getting "better" mileage with a 3.55 or 3.73 gears. It's mechanically engineered that you will have more revs sooner with lower gearing like that. More RPM, more fuel consumption, it's as simple as that.

I reserached all of this and specifically went with a non locking 3.31 rear axel because I never tow and dont do any aggressive off roading. Getting 4x4 mainly for the snow, and all I haul is gear / motorcycles in the bed. I wanted any improvement at highway MPG I could get, and wasnt concerned about lower / more responsive gearing at lower speeds.
 

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Well, I haven't had any issues with my truck. So, I would state everything is fine. Again, I have just read a lot of threads w/person(s) talking about the 3.73 gears and how the mpg is really no different, yet they get better city mileage and have more torque w/one mile per gallon better on the highway. Well, hell, that sounds like a cherry of a deal. Just wondering what is my advantage to having the 3.31(s). Thanks guys for the good insight.

Thanks again,

Al
IMO,I think the 3.31 gears are a little better on mileage then the 3.55.Performance wise from the 3.31 gears in my current truck to the 3.55 gears in the 2011 i had,the 2011 was 2 tenths quicker in the 1/4 mile.

Later Mark.
 

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I dont see how anyone is getting "better" mileage with a 3.55 or 3.73 gears. It's mechanically engineered that you will have more revs sooner with lower gearing like that. More RPM, more fuel consumption, it's as simple as that.

It's not always about RPM's, it's about effort. I'm not a mechanical engineer so i will have to speak from experience. I bought a new 94 Mustang GT with a 5-speed manual transmission & the only gear ratio available was 3:08's. I promptly had them switched out with 3:73's. Not only was the car much quicker but it got a little better gas mileage even though it was turning more RPM's. Why? I did not have to push the accelerator down as far to achieve the same speed because it took less effort from the engine to move the car with the lower gear ratio. So if your truck has 3:31's, your going to have to push the accelerator down further to get up to & maintain the same speed as someone would with a lower geared truck, especially if your towing.
 

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I dont see how anyone is getting "better" mileage with a 3.55 or 3.73 gears. It's mechanically engineered that you will have more revs sooner with lower gearing like that. More RPM, more fuel consumption, it's as simple as that.
It's not always about RPM's, it's about effort. I'm not a mechanical engineer so i will have to speak from experience. I bought a new 94 Mustang GT with a 5-speed manual transmission & the only gear ratio available was 3:08's. I promptly had them switched out with 3:73's. Not only was the car much quicker but it got a little better gas mileage even though it was turning more RPM's. Why? I did not have to push the accelerator down as far to achieve the same speed because it took less effort from the engine to move the car with the lower gear ratio. So if your truck has 3:31's, your going to have to push the accelerator down further to get up to & maintain the same speed as someone would with a lower geared truck, especially if your towing.
Yes this is true. After re-reading my statement, and driving with my instant mpg gauge on for the first 180 miles of owning the truck, I can see where you could baby the pedal more with lower gearing (that's a higher number rear differential) and get up to speed with a bit less effort than with the taller gearing like the 3.31 or 3.15... That said, I can go 75 mph and be under 2000 rpm with the 3.31 rear end. I'm happy with less revs per mile overall, but it won't matter if I have to get my foot into it more if I'm bogging.

all in all I'd say the 3.31 ratio has the potential to get slightly better mpg overall, but all the variables inevitably make it a wash. I simply didn't need lower gearing for anything so that's why I chose to order a standard 3.31 rear diff.
 

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Jared I could be wrong but I do not believe you should be towing in OD period. I'm having to rebuild the transmission in my 04 Super Duty diesel and I believe it is because I did not always tow in the tow & haul mode. I made 250 miles runs to Maine towing trailers with less then you are, it puts a tremendous amount of stress and wear on the OD clutches which are not made for towing.
Only the OD clutches are slipping on my 04 and only under load, usually in the winter with the plow on and 500lbs of sand in the bed. In talking with techs about this they all concurred that you should never tow even at highway speeds unless you are in the tow & haul mode.
I've always used tow & haul when plowing as well, 130K miles on an 04 with 9 winters of plowing commercially before transmission showed signs of wear, I'd say I was doing something right.
 

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I tow my gto (3500 lbs +1500 lb trailer) and my3.31 tow package pulls it effortlessly and gets about 15 highway mpg loaded
 
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