Why does the towing capacity on the trucks with a 3.55 rear drop 1,600lbs from what the 3.73 can tow?

 

I believe it is because of where the 5.0 makes it's power in the powerband.

 

I can not come up with a good reason why they do this. The dealer can't explain it. I talked to someone at Ford and they did not have a good reason. I think it is because they are trying to push the ecoboost. The 3.55 are way more popular than the 3.73 in a 5.0 truck.

 

You would have to speak with a Ford powertrain engineer to know exactly why the ratings were changed the amount they were. I can tell you though that there definitely was a reason, as they have pretty specific test methods and standards. In fact, you can read up on what their new methods will be once they adopt the SAE J2807 towing standard.

Most likely the change had to do with cooling capacity, as that's often a big limiting factor. Remember that taller gears make an engine work harder. It's possible that a 1,600lb difference was enough to lead to sub-optimal temperatures under certain test conditions (even to the point of overheating).

 

The 3.73 truck has what is refered to as the max trailer tow package, it comes with a 3.73 ring gear and heavier towing capacity.

 

i've been sitting on this one waiting to see where it goes..... which right now is nowhere, and in the wrong direction at the same time.

any vehicle, where engine output is a limiting factor, with numerically higher gears will have a higher towing capacity than the same vehicle with numerically lower gears. Deeper gears (numerically higher) provide more torque multiplication at the ground (given the same size tire). more gear reduction = more torque = ability to do work = more towing capacity. power band (as mentioned above) plays into this some as well, but gear reduction makes torque, and torque does work (moves the load). this is why a transmission will downshift going up hills, to multiply torque (and to some degree get the engine up into the powerband)

while it is true that ford has an interest in pushing the ecoboost, that has nothing to do with the question above. ecoboost trucks are offered with 3.15, 3.31, 3.55, and 3.73 gears. any ecoboost truck has more towing capacity than any 5.0 truck given the same gear ratio. why? because engine output is perceived as a limiting factor, and the ecoboost makes more horsepower and torque than the 5.0.

now .. looking to the super duty line, there are some configurations where the trucks with 3.73 gears have the same tow rating as the trucks with 4.30 gears.... why? because engine output is not perceived as a limiting factor. something else is limiting the tow rating, so torque at the ground is not a factor. that being said, a truck with 4.30's is probably going to feel better towing, than a truck with 3.73's (ask me how i know), even though it is not limiting the truck, it will still tow "better"

somewhat correct. for 09-12 you are right. for 13 that is not correct. in 13 you cannot get the "max tow" package with a 5.0. that package is reserved for the ecoboost and 6.2 only.

 

I would only postulate a guess but it would line up with the above statement and I have a hunch that has to do with trans temps more than anything (OD shifts and TC lock ups and the such).

 

Why are tire sizes not also used to determine the tow ratings? I bet it is possible to have a 3.55 truck with the shortest tires Ford offers geared lower than a 3.73 truck with the tallest tires Ford offers. I really don't think the trucks engine is limiting factor. What about the old trucks back in the 70's like a truck with a 351M, 160HP? You can gross 14K with one of them and they do okay. They are not going to set any speed records. I just think Ford has something messed up.

FWIW I found a 2013 F-150 Crew cab XLT 5.0 with 3.73's and the 302A package. The 5.0, 302A package and 3.73's are hard to find together.

 

comparing a truck from the 70's to today is not an even comparison. back then there wasn't a truck on the market that made anywhere near 360hp, so all of their tow ratings were based off of what was available at the time.

keep in mind that until now there was no standard for determining tow ratings. there is now an SAE spec, but ford is still not using that yet either.

so by ford's new standards, the tow ratings are what they are. looking at it from the most objective standpoint possible, they are considering horsepower to be a limiting factor up to about 9,000 lbs, where it appears that cooling becomes a factor.

can a 5.0 tow 10,000 lbs ... i'm sure it can. i tow that much with my 210hp 460 powered 79 f350. horsepower will not be holding you back, but you very well may have problems with something else, namely engine and transmission temps, particularly on long grades.

check out tom's thread on pushing the Max Tow to the max. his truck has the upgraded cooling package that comes with with the max tow option, and at the top of the hill his temps were at or above the top of the "normal" range. the 5.0 cannot be had (in '13) with the upgraded coolers (unless you add them yourself), so if you decide to push it beyond what ford recommends, don't be surprised if you have issues on long grades.

200 hp will get you to the top of the hill, but it takes a big radiator to keep things cool. the cooling package on the super duties is much better and keeps the temps down when pushed to the max.

 

It stands to reason that the smaller the wheel/tire size, the lower the gear ratio is going to be. My all time favorite was a 300 6cyl with 373 Gears and a "Bulldog" first gear! I have pulled people out of mud and ditches without even reviving the engine. Of Couse it had the 235/75R15" tires ( a plus for the gear ratio).
The reason we are getting less metal and other material in our newer trucks is for Ford to lower weight and meet Gov. imposed fuel economy. I had to replace the differential cover on a 2001! They used to be Cast Iron and last forever, but are now cheap, low grade metal for weight loss and profit boost and rust out quickly.
I would wager that if you took a high speed geared 5.0 engine and swapped the 20" wheels for 15" ones, it would at least be as good or better than a 20" setup with 373 gears. The power train begins at the engine and ends with the Gears and TIRE SIZE, all factors considered, it is all in ratio aspect. I am so tired I can't word this exactly like I would like, but most who know, will understand what I am saying. Those who don't just haven't experimented enough or else haven't been around long enough-yet!

 

I just visited the Silverado site. GM is advertising the the 2014 Silverado 5.3L ecotek V-8 as being capable of best in class specs. Ford and GM are both 6 speed transmissions. The 1500 Silverdo has a fully boxed frame like the F-150.

Here they are: 3.73 axle.

GCVWR: 16,700
Max Payload: 2007
Max tow: 11,400

Makes you wonder if GM is following the new SAE J2807 towing standards as well.
Makes me wonder if Ford isn't pushing the ecoboost engines.

 

I noticed how they are trying to market it as well, here is a clip from their webpage of the 2014 Silverado:

Our available EcoTec3 5.3L V-8 engine offers an EPA-estimated 23 mpg highway for 2WD models and 22 mpg highway for 4WD models. That’s better than any V-8 competitor and beats the EPA highway estimates for the Ford F-150 EcoBoost turbocharged V-6. With our EcoTec3 5.3L V-8 engine, you keep the benefits of a larger-displacement engine and get better fuel efficiency. We think of it as “doing more with more.”

 

ford has always under rated the weight and towing by at least 10 to 12%. I do think ford is just trying to push the new ego boost over the V8. Its no big deal for a V6 to be a work horse, why just 20 years ago you average small farm tractor had a 6 cylinder in it. slant, straight or V its all about tork and 6 cylinders seem to have more than enough!