An Engineer's Ultimate Guide To 3.21 VS 3.92 Axle Ratio

[nc_beagle]

Guess it's my age, but to this day whenever I hear the word Maverick I think of this:
View attachment 106682

It's this for me.

 

[HSKR R/T]

wrong brand. GM and Chrysler revive old nameplates to make MUCH more exaggerated versions of their originals, fords designers do something like this
designer 1: "they said we have to revive the maverick name and update the mustang lineup to get ahead of the competition"
designer 2: "well sure, what are we thinking"
Designer 1: "....Sh*tty Econoboxes??"
Designer 2: "Agreed, Sh*tty econoboxes, but make one of them a disappointing half truck and the other ELECTRIC so we can ruin our brand history AND still act like we did something cool."

Did you forget about the Dodge Dart?

 

[bigdodge]

Picked up my first Ram truck. It came with 3.21 gears but it identifies as a Ram with 3.92's...

did you pull your build sheet?
or
window sticker?

 

[CogitoErgoLevo]

Secretly, this is how the 3.21s identify:

 

[Redfour5]

Guess it's my age, but to this day whenever I hear the word Maverick I think of this:
View attachment 106682

LOL, I was going to go look for a pic just like the one you put in. YEP, I remember that. Ugliest car I ever saw. Big fat ***, skinny tires, practically rolled over going around a corner... Funny looking things...

 

[Redfour5]

It's this for me.

And that makes me think of... "Have Gun Will Travel..." Of course all the youngins are going WTF are they talking about?

 

[SuthrnRAM]

I've been on a search for a new truck and can't seem to find any RAMs with the 3.92 gears. Is there a way to search for them? I put it in the keywords in cars.com but it only brings up a few and none have the sport package.

 

[TNRamGuy]

placed my factory order 6 months ago with 3.21. fubar'd order, swtiched to 22, had to change colour, yada yada, you know the drill. when they replaced my order and i asked for the build sheet, all looks good, except now 3.92. so i sez WTF. manager sez my mistake, i order all stock trucks that way, and i overlooked it when i entered yours. so i wonder if he's going to pay for the difference on the fuel bill on a long road trip. it's not a dealbreaker mistake, but i sure hope it's all that wonderful as some of you guys say. i will put one size larger tires (up to LT275 70 18) so maybe that will help.

Realistically if all the planets align perfectly, 3.92 will cost you at most, $1000 in gas extra,over 120000 miles(not sharing my math, cause I don't care if it is off a little) tell the dealership that they need to make it right! Running boards, tonneau, mud flaps. Seems like you can get something. Maybe free oil changes, maybe cai?

 

[IvoryHemi]

I've been on a search for a new truck and can't seem to find any RAMs with the 3.92 gears. Is there a way to search for them? I put it in the keywords in cars.com but it only brings up a few and none have the sport package.

That’s how I found mine, also used AutoTrader. You can add multiple keywords, so add Sport into your search. “3.92, Sport”

 

[Mountain Whiskey]

I've been on a search for a new truck and can't seem to find any RAMs with the 3.92 gears. Is there a way to search for them? I put it in the keywords in cars.com but it only brings up a few and none have the sport package.

I just clicked the box on the "Build my Ram" page that selected the proper 3:92 gearing. TA DA! It was in the truck that arrived at the dealer for me. Worked like a charm. Had all the options I wanted.

 

[Redfour5]

Realistically if all the planets align perfectly, 3.92 will cost you at most, $1000 in gas extra,over 120000 miles(not sharing my math, cause I don't care if it is off a little) tell the dealership that they need to make it right! Running boards, tonneau, mud flaps. Seems like you can get something. Maybe free oil changes, maybe cai?

Unless you tow a lot. Then a 3.92 might save you money. I'm on my last camping trip for this year and am right at 8 mpg. I got close to 9 in my 2015 same kind of towing, lot of mountains. The DT, however is a much better tow beast in a lot of subtle ways. And the 2015 was not bad at all. Oh, big surprise, lane sense is actually useful on certain kinds of roads and certain kinds of conditions. Now, I must admit the 22 mpg without the trailer upon occasion (lyometer) is pleasant to see...and the ride is luxurious. I have a BTS edition with 3.21. It tows a 6700 lb loaded trailer great except for the mpg...

 

[silver billet]

Unless you tow a lot. Then a 3.92 might save you money. I'm on my last camping trip for this year and am right at 8 mpg. I got close to 9 in my 2015 same kind of towing, lot of mountains. The DT, however is a much better tow beast in a lot of subtle ways. And the 2015 was not bad at all. Oh, big surprise, lane sense is actually useful on certain kinds of roads and certain kinds of conditions. Now, I must admit the 22 mpg without the trailer upon occasion (lyometer) is pleasant to see...and the ride is luxurious. I have a BTS edition with 3.21. It tows a 6700 lb loaded trailer great except for the mpg...

The 3.92 never saves you money, doesn't matter what gear you sit in/tow with, or what you do with the truck.

The 3.21 only saves you money when it is running in 8th gear. Other than that, there is no savings anywhere else for either gear ratio.

(This is ignoring the fact that you can manufacture a test where the 3.21 is revving higher at a very specific speed than the 3.92 (right before the 3.21 upshifts), and then hold that speed for a long period of time.)

Edit: Also the difference between your trucks of 8 and 9 is not really signficant. I've towed a number of times this year with my truck and trailer and I will get anywhere between 8.5 to 11 depending on external conditions, with wind being the biggest factor by far. Headwind = 8, tailwind = closer to 11. I was able to repeat the same test (going to the same place) several times so it's a great way to test for this kind of thing.

Wind has completely changed my mpg more than anything else. I've run my trailer empty, and loaded, and can't really spot a difference in either towing power or mpg. But a stiff/sustained head wind will suck my tank dry in "seconds". A few hours straight into a head wind... that's what it kills it for me.

 

[Redfour5]

The 3.92 never saves you money, doesn't matter what gear you sit in/tow with, or what you do with the truck.

The 3.21 only saves you money when it is running in 8th gear. Other than that, there is no savings anywhere else for either gear ratio.

(This is ignoring the fact that you can manufacture a test where the 3.21 is revving higher at a very specific speed than the 3.92 (right before the 3.21 upshifts), and then hold that speed for a long period of time.)

Edit: Also the difference between your trucks of 8 and 9 is not really signficant. I've towed a number of times this year with my truck and trailer and I will get anywhere between 8.5 to 11 depending on external conditions, with wind being the biggest factor by far. Headwind = 8, tailwind = closer to 11. I was able to repeat the same test (going to the same place) several times so it's a great way to test for this kind of thing.

Wind has completely changed my mpg more than anything else. I've run my trailer empty, and loaded, and can't really spot a difference in either towing power or mpg. But a stiff/sustained head wind will suck my tank dry in "seconds". A few hours straight into a head wind... that's what it kills it for me.

I agree on wind. Mountains?

 

[silver billet]

I agree on wind. Mountains?

Admittedly I don't do much in terms of mountain driving; but even there if you're lugging a trailer around and constantly shifting up/down, the amount of power you're asking from the engine in all that driving is huge compared to "steady state" driving; Like the wind factor, I'm sure it (mountain driving) will just drastically override any efficency you might have with a somewhat shorter first gear (unless you're spending miles and miles in first / second)? The efficiency from the 3.21 is real, but at most about 3 mpg and that's when you're doing 22+ in the first place and holding steady at 65 mph etc etc. If you're doing 8 mpg in the mountains, there is just nothing you're going to save anywhere from a difference in gear ratios, the advantages are too slight and the amount of gas required for that driving is so huge that it just clobbers the tiny advantages.

I'd love to read some real world testing on all this as I could very well be wrong, but I doubt anybody would go through the process. Maybe TFL truck would. But again, if you get 8 mpg in one test and get 8.5 or 9 in the other, was it the gear ratio that helped? Or other factors like slightly different tire pressure, a change in wind direction/strength, driver style, traffic, etc.

 

[Buz]

41 pages into this thread and I finally figured it out:

If you tow, 3.92 is better.
If you don't tow, 3.21 is better.

Period, the end.

 

[KWKSLVR]

41 pages into this thread and I finally figured it out:

If you tow, 3.92 is better.
If you don't tow, 3.21 is better.

Period, the end.

 

[Hasti17]

41 pages into this thread and I finally figured it out:

If you tow, 3.92 is better.
If you don't tow, 3.21 is better.

Period, the end.

And if you wanna fuss about fuel economy... Get the diesel.

 

[silver billet]

41 pages into this thread and I finally figured it out:

If you tow, 3.92 is better.
If you don't tow, 3.21 is better.

Period, the end.

41 pages .... and yet you still missed it

To maximize towing, get 3.92
To maximize mpg, get 3.21
To rock crawl, get 3.92

But ... for towing the white elephant in the room is that you still won't "need" the 3.92, because you are payload limited. Since we all (probably) use our truck for much more than just towing (heavy towing usually is just recreational in 1500's), then why waste extra fuel 95% of the time while not towing, when the 3.21 can save you gas AND tow at the same time, within the limitations of our payload?

The 3.21 just makes the most sense for our 1500s. There are some very select use cases for the 3.92, but most of the guys on this forum preaching about how badly we need the 3.92 don't actually need it and are just wasting gas. Each to their own.

 

[KWKSLVR]

I like choice and I'm glad people can choose which they want for whatever perceived benefit they need and the manufacturer isn't trying to dictate what people want/need with only 1 option.

 

[Buz]

41 pages .... and yet you still missed it

To maximize towing, get 3.92
To maximize mpg, get 3.21
To rock crawl, get 3.92

But ... for towing the white elephant in the room is that you still won't "need" the 3.92, because you are payload limited. Since we all (probably) use our truck for much more than just towing (heavy towing usually is just recreational in 1500's), then why waste extra fuel 95% of the time while not towing, when the 3.21 can save you gas AND tow at the same time, within the limitations of our payload?

The 3.21 just makes the most sense for our 1500s. There are some very select use cases for the 3.92, but most of the guys on this forum preaching about how badly we need the 3.92 don't actually need it and are just wasting gas. Each to their own.

Ah, but you're splitting hair's here. The rabbit hole it much too deep on this topic, so I figured out the easy answer which is what I posted:
If you tow, 3.92 is better.
If you don't tow, 3.21 is better.

To solidify my point:
Heavy Load (i.e. towing) the 3.92 Gets it going easier (1st & 2nd gear) and Keeps it going easier (8th) assuming the driver simply puts the truck in 'Drive' and goes.