3.21. vs 3.92 gear

[Willwork4truck]

There's kind of two different train of thought's that people have been taking in this thread. Either someone says you need a 3.92 to tow anything at all, or someone says the 3.21 has the same transmission so it must be able to tow the full 12k instead of 8.

Neither of those are correct. This is not as black and white as that, in either extreme. I'm in the middle defending both sides of the argument as long as it's within the rated capability of the truck.

Here's what I'm saying. If your truck is rated to tow 8k, then you'll be fine towing 8k or less. If your truck is rated to tow 12k, then you'll be fine towing 12k or less. It's up to YOU to choose the correct truck for YOUR application, and is NOT the forum's responsibility to guide you on what's "OK" when it comes to overloading a truck and using it beyond it's intended capability. That part to me IS pretty black and white. If you know what you need for a weight rating, get the right truck. If you don't know what you need for a weight rating, and buy a truck that ends up not being capable enough for what you want to do, you either need to compromise on what you're trying to tow, or get a more capable truck. It really is that simple.

(The "YOU"'s there are collective you's, not personal, fyi)

Agree with above, my caveat would be to “get (slightly) more truck than you need”, not crazy more but set it up so you have “margin”...
A truck “can” tow or carry more weight on occasion however it (and you, and people behind you) may be a lot happier had you made a different choice. Usually that “different choice” will cost you more than if not made, but there’s other factors that come into play as well.

 

[JJRamTX]

I don't agree with your rpm statement. I don't care what gearing you have, maximum torque for the engine is reached at the same rpm (3500 or so). The transmission is gonna find the big torque #'s when under load. It might be 5th gear at 65mph with a 3.21 or 6th gear with a 3.92. Either way, the truck will be running similar rpm's towing and the 3.21 will turn fewer rpm's empty at similar speeds which will result in less wear and tear on the 3.21 equipped truck.

I am only referring to when Towing a heavy load, say 9,000 Lbs. Having a engine with a 3.21 up or down a slope will make the engine rev higher to power or control the load in a lower gear. (more fuel and wear and tear)

And when towing I don't need the Tow/Haul mode unless my trailer weight is over 7K with the 3.92 so I stay in 8th gear at 75Mph turning about ~2100 Rpms (I do a lot of towing: ~7,000 towing miles so far, so a 3.92 and e-Torque make total sense)

 

[silver billet]

I think the key element here is "maximizing"; if you want to maximize mpg, get the 3.21, if you want to maximize towing get the 3.92. Both are good options and both will work great unless you're really bumping up against the extremes of one of those 2 elements in which case you need to be more careful which one you pick.

I personally don't feel comfortable towing > 8000 lbs (travel trailer) in any half ton, so the 3.21 seemed to line up better with my preferences.

 

[Lawman]

I just purchased a 2019 Ram Limited with 3:92 gears and my sons 2019 Ram Laramie with 3:21 gears.
While tacking 2,000 rpm my truck is running 72 mph. My sons truck is running 84 mph at 2,000 rpms.
I do feel the torque difference.
I guess it’s all about what you are going to use your truck for.

Wow! That's the info. I've been looking for! Pretty much tells me all I need to know..

 

[Diamondback]

Wow! That's the info. I've been looking for! Pretty much tells me all I need to know..

Yeah, that's why I also passed on the 3.92s since I wasn't going to tow and knew my RPMs would be lower (saving fuel) at the highway speeds.

 

[Gman]

...and that pretty much sums it up for me. I do road trips on the interstate more than I tow. I can cruise down the highway at higher speed and lower RPM and get good economy. The 3.92 doesn't have a 9th gear.

Based on some of the questions after my post about mechanical advantage, I'm not sure some folks understand. More rotations for less distance traveled with the 3.92. That's what gives the advantage with Max Tow. It doesn't mean the 3.92 is "faster" than the 3.21. There are videos out there of guys with stock 2019 Ram 1500s and the 3.92 diff losing drag races to 3.21 equipped trucks.

 

[Willwork4truck]

I think the key element here is "maximizing"; if you want to maximize mpg, get the 3.21, if you want to maximize towing get the 3.92. Both are good options and both will work great unless you're really bumping up against the extremes of one of those 2 elements in which case you need to be more careful which one you pick.

I personally don't feel comfortable towing > 8000 lbs (travel trailer) in any half ton, so the 3.21 seemed to line up better with my preferences.

‘Xactly. I’m an old miser when it comes to gas so I chose 3.21. If I wanted to use the truck as a truck, tow/haul stuff, then 3.92’s (only because in their infinite wisdom RAM didn’t offer the 3.55 with the hemi).

 

[Willwork4truck]

...and that pretty much sums it up for me. I do road trips on the interstate more than I tow. I can cruise down the highway at higher speed and lower RPM and get good economy. The 3.92 doesn't have a 9th gear.

Based on some of the questions after my post about mechanical advantage, I'm not sure some folks understand. More rotations for less distance traveled with the 3.92. That's what gives the advantage with Max Tow. It doesn't mean the 3.92 is "faster" than the 3.21. There are videos out there of guys with stock 2019 Ram 1500s and the 3.92 diff losing drag races to 3.21 equipped trucks.

Yep, good info. The point is that when at highway rpm’s, at speeds above say 70-75 (as most highways are) you’re just burning more fuel with 3.92’s. Out west with 80 mph limits its worse. Now if you are in mts a lot (Rockies) you “could” make a case for the 3.92’s just for more power on hills and descent control perhaps. We are just restating the (not so) obvious here. RAM has given us just 2 choices thus the problem, and if you think you may want/need the extra TQ advantage (or plan on a big lift/tire combo) you’ve really got no choice but 3.92. Back in the day everyone had 4.10/4.11’s or even lower as with 3 and 4 speed trannies and lower powered motors, you simply had to.

 

[Diamondback]

I had the discussion with my dealer yesterday. My build sheet had 3.55s avail but I chose the stocks.

3.21s in the mountains : I think I think I can (well lemme downshift then upshift then downshift)
3.92s in the mountains : I'm still in 7th gear - let's go!! (and don't worry about the fuel gauge! I got you!)

LOL

But yes - each person has to take into consideration of HOW they will use their vehicle (not just their RAM.)
Get guidance and advise from others who use their vehicle the way you would.
It all comes down to you!
I love my Durango R/T - it only has 3.08s and the HEMI is rated 30 HP / 20 TW lower but has AWD and weighs 5500# without me in it .. and it beats the snot out of the 2 RAMs I drove (Hemi and Hemi eTorque) but I want a truck and the RAM seems like it has the "umph" I want once it breaks in the engine and I love that interior!

Now if I can just make sure the Truck sounds as good as the Durango when I take off

 

[Todd]

I took the chance of getting the 3.21 over the 3.92, and glad I did.
Towing frequently... my towing #'s are at the bottom of my signature,
through out the year, and so far according to my calculations.... based on what I'm using my truck for. I'm very much pleased with my decision....on the 3.21.

My results are from here in the Carolina's. Since I live in Central NC. Traveling to the beach and the Appalachian mountains frequently.

So, I can only report that the terrain, the way I drive, and the way I tow, when I'm towing, have me smiling at the pump.

Again, I can only speak for myself.

Are there any other members on here from my location central NC, with results using the 3.92 using the Ram for similar situation as me?

 

[Gman]

I had the discussion with my dealer yesterday. My build sheet had 3.55s avail but I chose the stocks.

3.21s in the mountains : I think I think I can (well lemme downshift then upshift then downshift)
3.92s in the mountains : I'm still in 7th gear - let's go!! (and don't worry about the fuel gauge! I got you!)

Unless you're towing in the mountains, the 3.21 has no issues with them. No transmission gear hunting, no over-revving. The Hemi has plenty of grunt and the transmission is fantastic.

 

[Diamondback]

Unless you're towing in the mountains, the 3.21 has no issues with them. No transmission gear hunting, no over-revving. The Hemi has plenty of grunt and the transmission is fantastic.

I still like how my Durango R/T drives, though LOL

 

[Willwork4truck]

I took the chance of getting the 3.21 over the 3.92, and glad I did.
Towing frequently... my towing #'s are at the bottom of my signature,
through out the year, and so far according to my calculations.... based on what I'm using my truck for. I'm very much pleased with my decision....on the 3.21.

My results are from here in the Carolina's. Since I live in Central NC. Traveling to the beach and the Appalachian mountains frequently.

So, I can only report that the terrain, the way I drive, and the way I tow, when I'm towing, have me smiling at the pump.

Again, I can only speak for myself.

Are there any other members on here from my location central NC, with results using the 3.92 using the Ram for similar situation as me?

I’m in Raleigh and don’t tow thus the 3.21 was an easy choice.

 

[devildodge]

Because I love this thread so much

392 HEMI 6 speed auto 3.73 gears.


I know, you 3.21 guys are like, big whip, 20 or more...don't show up.

That was on our trip yesterday from Central Pennsylvania to Virginia Beach.

Mind you, my MDS isn't working (I got the infamous fuel level sensor fail).

That was with 2 adults in the front and an 18, 12, and 6 year old in the back, my fully loaded toolbox and an 8 foot bed full of one weeks worth of supplies and beach gear.

I budgeted 16 MPG...so I am very pleased.

And, when I tow...do not got to worry where to pack the pillows.

Now, 2019 HD, with about 200lbs weight savings, 8 SPD auto and working MDS...maybe 20 MPG club

 

[Willwork4truck]

Because I love this thread so much

392 HEMI 6 speed auto 3.73 gears.
View attachment 29483

I know, you 3.21 guys are like, big whip, 20 or more...don't show up.

That was on our trip yesterday from Central Pennsylvania to Virginia Beach.

Mind you, my MDS isn't working (I got the infamous fuel level sensor fail).

That was with 2 adults in the front and an 18, 12, and 6 year old in the back, my fully loaded toolbox and an 8 foot bed full of one weeks worth of supplies and beach gear.

I budgeted 16 MPG...so I am very pleased.

And, when I tow...do not got to worry where to pack the pillows.

Now, 2019 HD, with about 200lbs weight savings, 8 SPD auto and working MDS...maybe 20 MPG club

If I had known I could have gotten that good of mileage with a 392 H and those gears, I’d have been tempted as that truck would have opened up camper possibilities for me instead of a camper shell, ha ha.
I tried the LEER cap on the 6.5’ bed F150, even went so far as build in two 28” wide wood framed bunks lengthwise... Had power in there as well, wife said “nope, not sleeping in that”...
Course I should have known after 34 years that it couldn’t compare to endless hot water and fluffy towels...

 

[Helmetface]

Anyone else get 3.92's just for 35's?

 

[SpeedyV]

Now, 2019 HD, with about 200lbs weight savings, 8 SPD auto and working MDS...maybe 20 MPG club

Now @devildodge, you know that’s not the way it’ll work. Look at the 2019 1500. Eight speeds, lighter weight, eTorque, and we get...worse mileage?!

 

[Willwork4truck]

Anyone else get 3.92's just for 35's?

Your certainly better off with those gears for 35’s, and if lifted thats the 2nd reason. I wouldn't want the increased rotating mass drag on 3.21’s.
My .22’s (which I did not want) are big enough to have to push down the road, and thats with touring tread, not some honkin’ M and S’ns

 

[devildodge]

Now @devildodge, you know that’s not the way it’ll work. Look at the 2019 1500. Eight speeds, lighter weight, eTorque, and we get...worse mileage?!

After we drove around down here a bit, I filled up with gas. The EVIC was down to 17.8 and hand calculated....17.64. 18 miles to the gallon was real...more than pleased.

Guess I will just keep my old 4th Gen @SpeedyV

 

[wacdenver]

Agree with above, my caveat would be to “get (slightly) more truck than you need”, not crazy more but set it up so you have “margin”...
A truck “can” tow or carry more weight on occasion however it (and you, and people behind you) may be a lot happier had you made a different choice. Usually that “different choice” will cost you more than if not made, but there’s other factors that come into play as well.

I recently purchased a crewcab 4x4 hemi with the 3.21. If I am going to be towing an ultra-lite or lite travel trailer between 4500 and 7000 lbs., do I need to worry either way since it is under the 8000 limit for the 3.21?