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3.92 Rear Axle Ratio

50K views 57 replies 27 participants last post by  Calson  
#1 ·
I am trying to determine if I should order the 3.92 Rear axle ratio. I am an average driver so I don't need to get off the line quick. Is there a difference in normal driving. I am getting the tow package in case I decide to get a boat or watercraft in the future. Thoughts?
 
#3 ·
Thanks - Additional Question

The gas mileage is important, so I will probably stick with the 3.21. I am also getting the Etorque for that reason. The only other item I am working through is the mrrors. Wanted the auto close mirrors but cannot get with the tow package. Which mirrors do you have? Ordering the tow package without the larger mirrors seems pointless to me.
 
#6 ·
The gas mileage is important, so I will probably stick with the 3.21. I am also getting the Etorque for that reason. The only other item I am working through is the mrrors. Wanted the auto close mirrors but cannot get with the tow package. Which mirrors do you have? Ordering the tow package without the larger mirrors seems pointless to me.
FYI FYI FYI...

If you want/need 360 surround view camera, then stick with non-tow mirrors, as you lose this feature if you go that route.

Stock mirrors are gargantuan to begin with, so if you don't tow, that's what I'd go with.

Neurobit
 
#4 ·
It is more than a small hit imho having driven 3.21 rentals compared to my Outdoorsman. I've only seen 17 as the average per the window sticker on long trips even though it was on the window when I bought it. And 21 mpg? HAH!. But, I'm OK with it. I knew what I was getting into. And frankly unless you are going to tow, I'd go with the Pentastar.
 
#9 ·
If you don't tow, you're better off with the 3.21. That's what I have and I absolutely love it.

I know that some half tons are rated for 10k plus, but my limit is about 8500lbs for a 1/2 ton truck-if I'm towing any more than that with any regularity I'm getting a 3/4 ton. A 3.21 truck will tow that so really whether you tow or not the 3.21 is fine.


What I've noticed now that I live in the Ozarks is that my 3.21 Ram downshifts on the steep and ubiquitous hills more than my 3.45 Durango does. I can fix that by locking out 8th but then I lose the additional fuel efficiency of MDS. So my opinion is if you live in a hilly or mountainous area get the 3.92s, if you don't then 3.21s will tow anything you need and get you about 2 MPG better
 
#7 ·
I went 3.92 on mine and glad i did. When I did the math the extra 1MPG i'm loosing is about $125 a year. I drove the 3.21 and then the 3.92 back to back and you can feel the difference. The 3.92 is much more fun Imo. I'm getting a solid 17mpg on my 19 ram after 1200 miles with one long road trip. Highway the highest I got was 21.6 of solid highway driving from Columbus to Indianapolis.
 
#8 ·
Same as ndemeis…….get the 3.92's, you won't regret it.
 
#11 ·
I had a 17 with 3.92 and now a 19 with 3.21. The 19 butt Dyno imo for normal driving is about the same. It feels like the 1st three gears are lower on the 19 so it feels about the same as my previous 3.92. If you are using this for much towing and or using the truck like a sports car then get 3.92. If you love a very low cruising rpm then get 3.21. I got 21.6 mpg in the 3.21 vs 16 in my 3.92 car interstate hand calculated. 3.21 will shift more to hold speed even for mild slope changes. Takes a little getting use to. Your initial sensation is the 3.21 hunts but after driving it for a while I seem to not notice it now. 3.21 are the gentleman gears. If I had it to do over again I would not care, either gear set is fine with me.
 
#13 ·
I think the primary selling point for Etorque is the fattened bottom end torque curve-supposedly. We need to see dynos still.


The fuel efficiency and smoothed over MDS seem minor benefits to me
 
#14 ·
According to the guy who test drove 2 identical trucks except for one had etorque had this to say.
"I don’t know...overall acceleration didn’t seem much different to me"


He said there was no noticeable difference from a stop between the two, except "maybe" the etorque optioned truck revved a big easier. Note maybe.


He didn't test to see if tow/haul would maybe add some torque on the etorque truck.
 
#15 ·
Butt dynos are worthless. I want curve charts
 
#16 ·
I doubt you will ever see a torque curve as every dyno curve I have seen always starts at too high of an rpm to show any low rpm benefit.


I still say it is for MPG, start/stop, and extended MDS - which is just what FCA has said.


I think since he ordered an etorque, his butt dyno would have been on the optimistic side and favored the etorque truck - and he didn't.


I did read somewhere the new 8 speed trans is programmed for longer and lower rpm driving in city and other situations.
I wonder if they will change the programming in the existing transmission - I would be one happy camper as that is my only real gripe.
 
#17 ·
3.21's if you drive like a grandpa and are worried about fuel mileage, and 3.92's for more fun, towing or if you plan to throw on some bigger tires in the future. I've had both, I found about a 20% fuel mileage drop with the 3.92's but the truck doesn't shift as much on the highway. I'd get the 3.92's imo.
 
#19 ·
I ordered the 3.21, primarily for the mileage and my driving habits. I have the 18 inch wheels and do very little towing. There may be a boat in my future, but it would be small (< 3,000 lbs) and my town has a marina so the towing distance will be less than 30 miles. I want the truck to ride nice and be fun, but I have no desire to spin the tires. Most of my driving, except for snow in the winter, will be 2WD. If I get a 2MPG savings I should save $300 - $400 in fuel.
 
#26 ·
Tire size?
 
#31 ·
There were a few 8 speed 3.55s made in 2013, but for the most part they kanked the option when the 8 speeds came out. With the 5 and 6 speed there was about a ton difference in capacity between 3.21 and 3.55 and another ton or so between 3.55 and 3.92. With the 8 speed the spread closed to around 1000 lbs between 3.21 and 3.55 and 3.55 to 3.92. They probably dropped it because of the minimal difference.

I drove my dad's 5 speed 3.21 Ram when I was in AZ in April, and my truck pulls waaaaaayyy harder off the line
 
#34 ·
You have 4.10s though
 
#36 ·
But it also had a 5 speed.

Diff gears are only half of the final drive ratio equation
 
#40 ·
I have the same vehicle with the 5.7 and 3.92 gears. I don't get 14 mpg regular driving and 9ish when pulling a 22 foot TT. In retrospect, if I had a choice, I would have gone with your set up.

I had a 13 quad cab with the old tranny, 5.7 and the 3.55 gears and to be honest, it would kick you back in the seat better than the 8 speed which is a bit more civilized in how it takes off. Passing on 70 mph two lanes in MT is my comparison point. Oh, it got roughly the same mpg as the 8 speed with the 3.92 gears.

Irrespective, I do like my truck. I just suck it up on the gas.
 
#39 ·
3.92 gears aren't even an option for V6 (gas) trucks