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Crossposting from ramforum.com as I wanted more data points and insights: Regretting ordering 3.92 on my 22 Ram Ecodiesel and almost debating paying to downgrade to 3.21

Here's the gist of the post:

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 = 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).

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.



I did do some analysis on things after the comments in that original post, assuming that the swap ends up costing me 5k for parts and labor, it would take me over 50k miles (which would be at least a few years) to recuperate the costs of swapping. So I'm thinking it's not worth it but I wanted to get as much data as I could. Thank you,
 

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2015 RAM 1500 CC 4x4
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If you realy want to do the change $2750 for parts and labor is cheap jump on it.

on the other hand the decrease in mileage is part gearing part wind resistance of traveling faster, I’m not sure your going to see a huge difference in economy after making a gearing change.
 

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Welcome to the forum. Yeah, I would say you're a little crazy on wanting to switch rear ends;) That being said I've felt the same way about decisions I have made also. Another 'longshot' suggestion is trying to find someone that had 3.21 gears, but preferred 3.92 gears in Cali area. Save some money on parts and you both win.
 

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2015 Outdoorsman EcoD CC w/6.4' 4X4
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If you realy want to do the change $2750 for parts and labor is cheap jump on it.
The $2750 is just for parts hence the "+ labor"
The entire front axle/differential has to be replaced as it's not able to be upgraded.
I'd imagine the labor will be close to $1K per book price.
In the grand scheme of it all, he might gain a mpg or two at the top end speed but may loose that in stop/go traffic.
GDE is not an option due to the state he lives in
 

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Ah I misread I thought parts and labor. I asked a dealer about swapping from 3.55’s to 3.92’s and they ahoy me right at $4,000 all in a few years ago.
If I really wanted to I’d find a front dif and rear axle from a salvage yard.
 

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2019 Ram 2500 Cummins - EX Ecodiesel owner.
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Big "can of worms". Don't bother.

Try slowing to 70-75 mph. You will still get there but, if you are like me, being slower than traffic speeds does grate me a bit. If you can get 26-27 mpg at a slower speed, call it GOOD.
 

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I'm biased since I do a lot of towing. I ordered a 2020 with 3.92 gears and got what I wanted (a towing machine). My best fuel economy is 27.6, but I also drive between 55 - 72 mph on the highway and interstate. If it drives you crazy, then I would sell/trade your truck and order another one.
 
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Really wish I could have gotten GDE but unfortunately California is a PITA
In stock form, my 2020 tows nicely. I'll probably leave it stock for two more years before switching to the GDE tune. I'm kind of waiting to see if GDE comes out with a handheld flash tool. I didn't get the GDE tune on my 2015 until it had 93,000 miles on it.
 
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What you might consider is a tire change. I haven't done the math for your situation, but it is surprising what the rotational size of a tire does to your overall final ratio. On the 2018, the 2 different tire/rims that were offered changed the final ratio by 5%. But by all means, get a tire that is eco friendly built not an off road tire.
 

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2017 Ram 1500 4x4 Bighorn CC/SB EcoDiesel
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Crossposting from ramforum.com as I wanted more data points and insights: Regretting ordering 3.92 on my 22 Ram Ecodiesel and almost debating paying to downgrade to 3.21

Here's the gist of the post:

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 = 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).

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.



I did do some analysis on things after the comments in that original post, assuming that the swap ends up costing me 5k for parts and labor, it would take me over 50k miles (which would be at least a few years) to recuperate the costs of swapping. So I'm thinking it's not worth it but I wanted to get as much data as I could. Thank you,
I think you're going to find the general consensus is the same on this forum as it is on the "other one" but I'll repeat myself AND add a little more...
1. Find another EcoDiesel (either dealership or even possibly a nearby forum member) setup similar to your current truck but with 3.21 rear end so you can get a good comparison b4 going through the hassle and expense of swapping.
2. If you truly prefer the 3.21 rear, consider trading in your current ride and ordering exactly what you want. If you work the deal right Financially it'll come out about the same but you'll have a completely new truck and warranty instead of one that's had the drivetrain violated.
 

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I think the tire thing at least depends. I replaced my Goodyear SRA’s with 10 ply cooper AT’s and lost no mileage. A the heavier tire might be harder to start but I’m convinced a 10 ply with 55 psi give or take is lower rolling resistance than the stock P tires at normal pressure for them.
 

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If you've got the money, keep your current truck as a backup and for towing. Buy a second truck for running empty and commuting. My 2015 with 3.55 gears is used as my daily driver and occasional tow rig. I use the 2020 has the primary tow rig. Both trucks should last a long time since I'm only averaging about 11,000 miles per year on the 2020 and 15,000 miles per year on the 2015. If one truck goes down, then I always have a backup. With today's part shortage, having a backup is actually a smart thing to do if you can afford it.
 

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Crossposting from ramforum.com as I wanted more data points and insights: Regretting ordering 3.92 on my 22 Ram Ecodiesel and almost debating paying to downgrade to 3.21

Here's the gist of the post:

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 = 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).

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.



I did do some analysis on things after the comments in that original post, assuming that the swap ends up costing me 5k for parts and labor, it would take me over 50k miles (which would be at least a few years) to recuperate the costs of swapping. So I'm thinking it's not worth it but I wanted to get as much data as I could. Thank you,
I don't think you will see a large jump in economy. 80 mpg will net you low mileage in a truck. Just the reality of aerodynamics
 

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We had a 2014 with the 3.2 diff and over the near 250k miles we had it the lifetime average fuel economy, by calculation, not gauge was a touch over 22 mpg. The best seen was around 30. We now have a 2020 with the 3.9 diff and over teh close to 80 k miles so far average fuel economy is essentially the same as that of the 2014. Both are 2wd crewcabs with similar options. The 14 had the stock 17" wheel package, the 20 has the stock 18" wheel package. Useage, including towing has been quite similar with towing about 25-30% of the miles driven. So I'd call it a wash for fuel economy.
 
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Crossposting from ramforum.com as I wanted more data points and insights: Regretting ordering 3.92 on my 22 Ram Ecodiesel and almost debating paying to downgrade to 3.21

Here's the gist of the post:

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 = 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).

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.



I did do some analysis on things after the comments in that original post, assuming that the swap ends up costing me 5k for parts and labor, it would take me over 50k miles (which would be at least a few years) to recuperate the costs of swapping. So I'm thinking it's not worth it but I wanted to get as much data as I could. Thank you,
Crossposting from ramforum.com as I wanted more data points and insights: Regretting ordering 3.92 on my 22 Ram Ecodiesel and almost debating paying to downgrade to 3.21

Here's the gist of the post:

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 = 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).

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.



I did do some analysis on things after the comments in that original post, assuming that the swap ends up costing me 5k for parts and labor, it would take me over 50k miles (which would be at least a few years) to recuperate the costs of swapping. So I'm thinking it's not worth it but I wanted to get as much data as I could. Thank you,
This is a huge mistake. I have a '21 Laramie, 4x4, 6'4" bed, large fuel tank, air suspension, etc, with 3.21 gear. I ordered it this way after I drove a '16 with 3.92 gear for almost 5 years. On a trip this spring from Long Beach, CA to Joshua Tree and back driving 75 to 80 I got 28.7 mpg (per EVIC). I did not hand calculate but my experience with the old truck tells me this is within 2 or 3 tenths of actual either side. My old truck with GDE tune was about 29 in similar conditions. The ROI simply isn't there.

Cost aside, you are opening a big can of worms. One reason I sold the old truck, other than high used values, was I didn't want the dealer taking engine apart to replace EGR cooler and possibly manifold. This is the same dealer who overfilled the crankcase on one occasion and changed a tie rod end to correct a clunk in the front end. Which never resolved the issue. So, at age 64 my motto is "if it's not broken, don't fix it". The factory is much better at assembling these trucks than a dealer ever will be disassembling and then trying to get it back the same way.
 

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2020 Eco Laramie SB CC 3.21
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I have a 20 ED with 3.21 and pull a 7k camper. I see no need for the 3.92 and I have another 2k trip in a month pulling it. Avg 25mpg city/highway to work and 14mpg with camper. I pull camper around 68-72mph. Weekly driving is a lot of stop n go.
 
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