Regretting ordering 3.92 on my 22 Ram Ecodiesel and almost debating paying to downgrade to 3.21

Hi, I had ordered my RAM with 3.92 ratio as I only seemed to come across the good articles at that time in which I learned that it will have a higher resale value in the future, better for towing, etc. I did see some mention of a negligible difference in mpg but thought nothing of it as the sticker did not update on the MPG at all after I selected 3.92. I had even picked up the bigger diesel tank because I wanted to be able to go on long trips while dreaming about the 29mpg thats advertised lmao.

I live in California, almost everyone and their mother drives 80mph here on the highways and most drive even faster. I live in a fairly rural area, I have to drive on the highways a fair bit in order to get most things.
In my first few weeks of testing, here's what I've noticed for mpg
80mph = 2200/2250 rpm and ~20mpg
75mph = Just over 2000 rpm, maybe 2050/2075 and ~24mpg
70mph = I dont remember the exact rpm but its 27+mpg
EDIT: 70mph = a hair under 2000 rpm maybe 1950 and ~27.5 mph

I did reach out to the service department at my local dealer and was told $2,750 + labor in order to switch to a 3.21 (guy sent me a detailed parts list as for the breakdown) and I'm following up with them now to see how much labor that would be.

In terms of switching over
Pros:
For the most part I can drive as I normally do and not have to worry about being inefficient in terms of diesel
Would be saving time as well as I'd be driving at 80mph instead of 70/75

Cons:
The upfront cost of course
Potential resale value in the future may be impacted but I dont like switching cars very often
Towing impact, I dont tow much now but it was just futureproofing


You may be calling me crazy but this is bothering me so much, like how did I look into every little detail and end up making this big of a mistake. Also, I am under the assumption that going to 3.21 will give me lower RPM's at 80mph, please correct me if I'm wrong.

If I were you, before I spent a dime on anything I would go to a dealer that has an eco diesel with 3.21 gears and drive it to compare the two. Drive it as you normally would to see if there's any real difference. I have a 5.7 with 3.21 and only tow occasionally and I'm happy with it. As far as resale value is concerned, I couldn't care less but I think you're over thinking that. And a lil FYI... fuel economy has so many variables that will affect the outcome literally everytime you drive

You probably won't even notice the mpg gain dropping to 3.21. It's not the gear ratio eating the fuel it's the wind drag at higher speeds.

aj_g said:

I am under the assumption that going to 3.21 will give me lower RPM's at 80mph, please correct me if I'm wrong.

Click to expand...

Your not wrong about the rpms(about 400 rpms less) but your overlooking the wind drag going at higher speeds which killing the fuel economy. These trucks have the aerodynamics of a cinder block

aj_g said:

Hi, I had ordered my RAM with 3.92 ratio as I only seemed to come across the good articles at that time in which I learned that it will have a higher resale value in the future, better for towing, etc. I did see some mention of a negligible difference in mpg but thought nothing of it as the sticker did not update on the MPG at all after I selected 3.92. I had even picked up the bigger diesel tank because I wanted to be able to go on long trips while dreaming about the 29mpg thats advertised lmao.

I live in California, almost everyone and their mother drives 80mph here on the highways and most drive even faster. I live in a fairly rural area, I have to drive on the highways a fair bit in order to get most things.
In my first few weeks of testing, here's what I've noticed for mpg
80mph = 2200 rpm and ~20mpg
75mph = Just over 2000 rpm and ~24mpg
70mph = I dont remember the exact rpm but its 27+mpg

I did reach out to the service department at my local dealer and was told $2,750 + labor in order to switch to a 3.21 (guy sent me a detailed parts list as for the breakdown) and I'm following up with them now to see how much labor that would be.

In terms of switching over
Pros:
For the most part I can drive as I normally do and not have to worry about being inefficient in terms of diesel
Would be saving time as well as I'd be driving at 80mph instead of 70/75

Cons:
The upfront cost of course
Potential resale value in the future may be impacted but I dont like switching cars very often
Towing impact, I dont tow much now but it was just futureproofing


You may be calling me crazy but this is bothering me so much, like how did I look into every little detail and end up making this big of a mistake. Also, I am under the assumption that going to 3.21 will give me lower RPM's at 80mph, please correct me if I'm wrong.

Click to expand...

Do what @Rlaf75 suggested. You might not like how the 3.21 accelerates compared to your truck. That $3000 cost to switch will take quite a few miles to recoup as well.

The MPG difference between 80mph and 70 tells it all. Going to 3.21 is not going to get to 27mpg at 80. More likely 21mpg. And on anything other than a fairly long trip, the time saved isn't much. But, it's your money.

Considering I drive 60-65 around town and 70 on the highway, I'd be pretty tickled with 27+mpg instead of the 17-20 I get now.

aj_g said:

Hi, I had ordered my RAM with 3.92 ratio as I only seemed to come across the good articles at that time in which I learned that it will have a higher resale value in the future, better for towing, etc. I did see some mention of a negligible difference in mpg but thought nothing of it as the sticker did not update on the MPG at all after I selected 3.92.

Click to expand...

If you do the math on axle ratios and transmission output ratios you get a clearer picture. Back when RAM offered a 6-speed tranny with a 3:92 axle ratio and then began offering the new 8-speed with a 3:21 axel ratio the RAM forums went nuts. The math proved the 8-speed with a 3:21 axle ratio had lower gearing off the line than the 6-speed transmission with a 3:92 axle ratio. Lacking critical thought, the forums were not happy.

There is no shortage of opinion base justification but in usage cases, axle ratio decisions should be made on need. I can see that if one is going to be towing in the upper ranges of the vehicle's capacity and in areas that will cause a high amount of stop-and-go driving, then a 3:92 would be a better choice offering less stress on the drive line.

There is also the case for the age group that likes "jackrabbit" launches and/or traffic cowboying where a 3:92 will promote their desires.

Then there are drivers like me, older, living in a rural area, driving typical at speeds 50 MPH or more, minimal stop and go, and occasionally towing less than 7K pounds, 3:21s. The devil is always in the details which are typically not presented in opinion based posts.

Before I bought my 2022 ECO I had a 2013 HEMI RAM 1500, drove in the same areas as I now do, towed the same loads, and that 2013 also had a 3:21 axle ratio. I much prefer the ECODiesel as a daily driver and also for towing my lighter loads.

Since one's driving style is the major contributor to the vehicle's achieved MPG, it is difficult to compare the same vehicle with two different drivers, this is most obvious when reading forums and seeing what is posted for MPGs.

For your case, I say leave your axle ratios alone. In my 3:21 ECO, driving at 75 MPH, my engine is spinning at 1,650 RPMs and I'm realizing anywhere between 32.6 and 34.2 MPG on the open flat roadways. I've never driven the same vehicle with 3:92s so I can't compare the MPGs but I would think that spinning your engine 350 RPM faster than mine isn't going to make much difference in MPG. Likely your driving style and the cetane level in California fuel are going to be the major contributors to your mileage.

What is your fuel cost difference going to equate to in time to make switching the gears actually beneficial? How long before you turn profit. And these trucks turn into brick walls above 70mph anyways so the aerodynamics and drag will greatly reduce your fuel efficiency above 70mph anyways.

My last ram had the 3.92 gears and my current ram has the 3.21. I’ve contemplated going the other way. The difference in daily drive ability is very great in my opinion. I’d never opt for the 3.21s again. I thought it wouldn’t matter much when I bought it but I was wrong.

Rlaf75 said:

If I were you, before I spent a dime on anything I would go to a dealer that has an eco diesel with 3.21 gears and drive it to compare the two. Drive it as you normally would to see if there's any real difference. I have a 5.7 with 3.21 and only tow occasionally and I'm happy with it. As far as resale value is concerned, I couldn't care less but I think you're over thinking that. And a lil FYI... fuel economy has so many variables that will affect the outcome literally everytime you drive

Click to expand...

zogg said:

My last ram had the 3.92 gears and my current ram has the 3.21. I’ve contemplated going the other way. The difference in daily drive ability is very great in my opinion. I’d never opt for the 3.21s again. I thought it wouldn’t matter much when I bought it but I was wrong.

Click to expand...

Ok. Each gear ratio has its goods and not so goods. In my original comment I suggested the op drive one in the configuration he is thinking about so he can determine whether or not it's going to be worth it FOR HIM. Everyone has different wants and needs that's why there are different options available. When I comes to gear ratio's my opinion would be, they need to make the 3.55 ratio available with a V8 because that is a great all around ratio

When you configure the trucks the tow rating changes in a big way between 3.21 and 3.92 so if that's a factor add that to the pro/con list. It is easier on the Driveline in stop and go as well. Based on your mpg/mph sheet I'd say you'd do better than the dreamed 29mpg at 55 since that seems to be the magic max mpg number on average. Hard to believe that just dropping from 80 to 70 gained 7mpg and got you pretty close.

things really changed when they went to the 8 speed. mine has the 8 speed that has 5.0 1st gear and I have the 3.92 rear end and I bought mine that way because I often tow our travel trailer . It does a great job of that but not so good in stop and go traffic even tho that tranny does a smooth job of getting up thru the gears and out of the first few. I usually get 20 on the highway at 75ish when not towing so I consider that plenty fine for a 5700# truck.

I like the advice to go test drive another truck with 3:21 before you drop a bunch of cash on anything. If you like the 3:21 ratio you could put a slightly larger tire on resulting in near exact 3:21 ratio at the wheel and gain a little lift out of it. Its just another option.

There are internet calculators you can use to determine the tire size needed.

With the 8 speed and 3:92s you can handle a very large increase in tire size, the needed increase is easily handled, especially at 20ft above sea level.

I don't think you made such a big mistake, I'm going 3:92 over 3:21 every time. (I do live in the upper atmosphere tho.)

Since when is the 3.21 considered a "downgrade"? That's the kind of mindset that leads to problems like this. There are pros and cons to both gears.

The short answer is you did get the wrong gear ratio for your usage, but you'd have to calculate how much you save per tank in order to justify a conversion. Your best fuel savings will come driving at 60 mph, the EPA rates their trucks at about 55 IIRC, no way you're getting close to those ratings at 70+.

This forum hates the 3.21, but it's the better choice for most people based on what you see the average person doing with a truck. Especially with the diesel's low end torque, I can't imagine why you'd want the 3.92. You don't tow much, but the dirty secret is that both gears will tow just as much in the city and on the freeway, the 3.92 only gets you off the line slightly quicker due to having a deeper first gear but once you shift out of first and you're on the freeway, both trucks have the same gear ratios available for usage.

You are way overthinking this.....just enjoy the truck. At today's gas prices...especially in Calif.....slow down.....save some money......enjoy the ride......driving 80 mph is not smart.....

I test drove the 5.7L with the 3.21 and the 3.92. I took the 3.92 with LSD.

1. I like the get up and go of the 3.92 with LSD.
2. Fuel economy is fine. I pretty much do 50/50 HWY/CITY and I'm averaging +/- 20 mpg / 12 L/100kms.
3. Wanted to have max tow for my truck and the 3.92 gave me that.

I drive pretty conservatively with the odd floored take offs, I drive 105 - 110Km/h (65 to 70mph) on hwy.

So yeah, go drive one and see what you think.

aj_g said:

Hi, I had ordered my RAM with 3.92 ratio as I only seemed to come across the good articles at that time in which I learned that it will have a higher resale value in the future, better for towing, etc. I did see some mention of a negligible difference in mpg but thought nothing of it as the sticker did not update on the MPG at all after I selected 3.92. I had even picked up the bigger diesel tank because I wanted to be able to go on long trips while dreaming about the 29mpg thats advertised lmao.

I live in California, almost everyone and their mother drives 80mph here on the highways and most drive even faster. I live in a fairly rural area, I have to drive on the highways a fair bit in order to get most things.
In my first few weeks of testing, here's what I've noticed for mpg
80mph = 2200 rpm and ~20mpg
75mph = Just over 2000 rpm and ~24mpg
70mph = I dont remember the exact rpm but its 27+mpg

I did reach out to the service department at my local dealer and was told $2,750 + labor in order to switch to a 3.21 (guy sent me a detailed parts list as for the breakdown) and I'm following up with them now to see how much labor that would be.

In terms of switching over
Pros:
For the most part I can drive as I normally do and not have to worry about being inefficient in terms of diesel
Would be saving time as well as I'd be driving at 80mph instead of 70/75

Cons:
The upfront cost of course
Potential resale value in the future may be impacted but I dont like switching cars very often
Towing impact, I dont tow much now but it was just futureproofing


You may be calling me crazy but this is bothering me so much, like how did I look into every little detail and end up making this big of a mistake. Also, I am under the assumption that going to 3.21 will give me lower RPM's at 80mph, please correct me if I'm wrong.

Click to expand...

Let's see the math for you to break even on the $2,750 + labor cost.

BossHogg said:

In my 3:21 ECO, driving at 75 MPH, my engine is spinning at 1,650 RPMs and I'm realizing anywhere between 32.6 and 34.2 MPG on the open flat roadways.

Click to expand...

If you downshift to 7th maintaining the same speed, that will put you close to what 3.92 would do rpms wise, if you want to try and report back. :-D

Bigs said:

I like the get up and go of the 3.92 with LSD.

Click to expand...

Big difference between the Hemi and EcoDiesel is where the torque peak is, the EcoDiesel is 480 ft/lbs @ 1600 rpms where the Hemi is 410 ft/lbs @ 4K. It's almost dangerous driving around corners in an EcoDiesel with 3:92 gearing when the roads are slick or wet.

I am lucky enough to have the Eco-diesel with 3.55s & LSD

I will likely never tow, but my bed usually has 700 pounds in it

a 3.21 was my first choice, but it was not available

at the traffic light, the grandma in the other lane beats me off the Line. I build up to highway speed slowly most times, it depends on the speed of the rest of the traffic.

California has a drag strip at every On Ramp during high traffic hours, the Ramps are Metered.
The Stop Bar at the Ramps traffic light is the Line, it changes to Green & you are expected to Merge with Traffic at speed, hell, you can do 100 mph in a quarter mile & not get ticketed

That is not me any more, i drive 73 MPH on the Highway that is posted 70 MPH

I know that i save fuel & most times i get to the next town at the same Time as those that went racing by me.

Let your Ram get about 4 to 5,000 miles on it, you may find the your MPG improves, like with the gas engines

Rlaf75 said:

If I were you, before I spent a dime on anything I would go to a dealer that has an eco diesel with 3.21 gears and drive it to compare the two. Drive it as you normally would to see if there's any real difference. I have a 5.7 with 3.21 and only tow occasionally and I'm happy with it. As far as resale value is concerned, I couldn't care less but I think you're over thinking that. And a lil FYI... fuel economy has so many variables that will affect the outcome literally everytime you drive

Click to expand...

You make a lot of sense, ty for the suggestion.
Im a bit mentally stuck on the mpg because my old 2017 Ram 1500 used to get 25-26mpg while driving as I normally do