3:21 vs 3:92 Gears

[Scram1500]

These threads are always hilarious. They make it sound like the 3.21 rear end makes the truck into a dog that won't get out of it's own way.

Or gets insanely better gas mileage

 

[screamin chicken]

I ordered mine with the 3.92, and the 33-gallon gas tank good thing because I am getting 16 MPG and the same on the interstate, I have a 2021 Limited with E torg that I just turned 3200 miles on, hopefully, the more miles the better my MPG will be.

 

[Mirowpl]

Had 3.21 on my 2009 with he I and had zero problems towing my 21 ft boat on tandem trailer and marching band trailers for son’s high school. Remember back then we only had the 5 speed. Now with the 8 speed, the 3.21 is very close to the 3.92. My 2020 I decided to go with the 3.21 as I was familiar with it. The 8 speed making it fun to drive and it can still tow what I need. If you need more towing the get the 3.92, but for most of us the 3.21 is all we need. Besides, if you want to be quicker off the line in the 3.21, put it in tow/haul mode, rev the heck with brake on then let it go when green. It will get up and go. You can you us it in traffics as well to make the truck a bit sporty moving in and out of traffic.

 

[Royalist_Ram]

Just test drive both and see what ya prefer. 3.92 is supposed to be better for towing and off the line acceleration. 3.21 is better for fuel economy. It just depends on what ya like.

 

[OldMarine]

a Pedal Commander takes care of any "sluggish off the line" issue..3.21 overall is a better choice, UNLESS you plan to tow heavy.

 

[jimchi]

I test drove both and I really didn't notice a difference. I ultimately decided on the 3.21 because I do a lot of highway driving for work, and even an 1-2 MPG difference will reduce my costs (and therefore maximize my reimbursements).

 

[Neurobit]

^^^ This ^^^

 

[flyfingers]

3.21's contribute to a quieter ride at hwy speeds due to decreased engine rpm's

 

[Zig10]

If I wasn't hauling a 7500 lb boat and fishing gear, I'd have gotten the 3.21 rear. I do a lot of highway driving along with my towing, and the MPG just sucks with the 3.92s.

It would be great if they offered the 3.55 rear with the Hemi. That would kind of sit in the sweet spot for my personal towing needs and at least net better than the 17.5 MPG I get on the highway.

 

[Dusty1948]

I had the 3.92s in my 2010 (6-speed) and my 2014 (8-speed). At that time I had a requirement to tow close to the 10,450 pound limit. Since that requirement disappeared, I ordered my '19 with the 3.21 differential and I now tow just under 7000 lbs. The 3.21s handle that just fine and my day-to-day average gas mileage has increased about 1.2 miles per gallon (lifetime-to-lifetime average).

Kentthelawnguy feels his with 3.21s is actually more responsive, and I have to agree. There's no doubt that 3.92s will likely launch better (if you can control wheel spin), especially with a 1st gear ratio of 5.000, but I find with the 3.21s 3rd and 4th gears seem to pull better at road speeds probably due to the 5.7s torque rpm band.

Best regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 03 June 2018. Now at: 045561 miles.

 

[Buz]

3.21 is best only if you:
-Care very much about MPG.
and
-Don't plan on adding larger tires.

Otherwise, do yourself a favor and get the 3.92.

 

[BowDown]

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[HEADING=3][HEADING=3][HEADING=3][HEADING=3]kenthelawnguy​

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JoinedOct 23, 2018Messages17Reaction score7

• Jan 11, 2021
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• #432

I had 3.21 gears in my 2017 limited 1500, 3.92 in my 2019 limited 1500 and I got the 3.21 in my 2021 Ram limited 1500. Why you may ask did I go back to the 3.21 gears? One thing I noticed after going to the 3.92 ratio was even though you get a little bit more of a kick off the line with the 3.92 and I mean just a little, you can really feel the pull of the 3.21 when you kick it down vs my 3.92 I had especially when kicking it down from higher speeds. Yes, to me the 3.21 just feels sportier and I don't know if it was due to ratio diff and the 3.21 finding a better gear when kicking it down or what but to me the 3.21 seems stronger once off the line and is more fun to drive. The truck feels lighter and smoother with the 3.21 and my wife even said the same thing and she could care less about trucks. Just my 2 cents on my personal experience. The best thing for you to do is test drive both, put them both through their paces and decide yourself witch you prefer out of both for you will find different opinions on both. Both gears tow well enough for what I would tow. If I needed to tow anything heavier I would step up to a 2500 Ram. The fuel economy is not that great of a difference so far between both gears with only 2000 miles on my new truck but let me tell you, the 33 gal tank is a must no matter which gears you go with!! High 500 to low 600 miles on highway to a tank is awesom

This is what people dont get about the 3.92. The 3.92 is only an advantage in 1st gear then its over, its too much gear for the 5.7 after that and you dont stay in a gear long. If the 5.7 could rev to 7K, the 3.92 may have more of an advantage after 1st but the 5.7 just doesn't have enough rpm to take advantage of the gear and stay in power like it does with the 3.21.
I'd put money on the race with a 3.92 truck vs a 3.21 that the race would be far closer than anyone thinks and from a roll, the 3.21 truck drive away from a 3.92 truck simply because it stays in the peak power band longer.
The only advantage to the 3.92 is from a dig and that advantage, I'd bet is less than 1/2 a truck length.
That said, expecting either of these gears to be fast in this truck is funny, I have zero need for this truck to be a 13 second 1/4 mile truck, it would be fun but highly useless. I have a 620 whp Z06 for that

 

[BowDown]

Or gets insanely better gas mileage

IDK, most 3.92 guys are saying they get 13-15 in the city, I'm getting 17-18mpg where my previous 3.92 truck was getting 12-13. To me, that is insanely better mileage. I also average 420-430 miles per tank on a 26 gallon tank (refill with 23-24 gallons).
I'd bet a 3.92 truck isnt getting that

 

[redneck]

when i test drove both back to back same day same interstate at 80mph the 3.21 was reading 3.4mpg better than the 3.92 on the lie-o-meter. also i saw some 0-60 results that the 3.21 was .4 second faster

 

[brian42]

Coming from an HD diesel with 3.73 gears I wanted the 3.92. The only truck I could find that I wanted had 3.21 gears. After the test drive I didn't notice much of a difference as it's a truck and that's how I drive it.

If I was planning on a lift, bigger tires, or E-rated tires I would have stuck to my guns for the 3.92.

If I was towing heavy I would have stayed in the HD club with a diesel and a full-floating rear axle.

 

[PhillyPhan]

Coming from an HD diesel with 3.73 gears I wanted the 3.92. The only truck I could find that I wanted had 3.21 gears. After the test drive I didn't notice much of a difference as it's a truck and that's how I drive it.

If I was planning on a lift, bigger tires, or E-rated tires I would have stuck to my guns for the 3.92.

If I was towing heavy I would have stayed in the HD club with a diesel and a full-floating rear axle.

I'm coming from the same diesel and figured I'd need the 3.92. I'm no longer wanting to lift my truck and don't tow anything. Maybe an 18' aluminum boat at some point, but most my driving will be highway driving to work. 3.21 is what I originally wanted. You have me thinking that's the way to go.

 

[silver billet]

IDK, most 3.92 guys are saying they get 13-15 in the city, I'm getting 17-18mpg where my previous 3.92 truck was getting 12-13. To me, that is insanely better mileage. I also average 420-430 miles per tank on a 26 gallon tank (refill with 23-24 gallons).
I'd bet a 3.92 truck isnt getting that

That's because they don't understand how signifcant 2 mpg is, when the range is 15 to 20 mpg. Turn that number into a percentage and suddenly 10% to 20% sounds a whole lot more significant.

 

[Jason605]

I'm coming from the same diesel and figured I'd need the 3.92. I'm no longer wanting to lift my truck and don't tow anything. Maybe an 18' aluminum boat at some point, but most my driving will be highway driving to work. 3.21 is what I originally wanted. You have me thinking that's the way to go.

If all your towing is an occasional 18' aluminum boat get the 3.21 IMO.

 

[MrSixStrings12]

That's because they don't understand how signifcant 2 mpg is, when the range is 15 to 20 mpg. Turn that number into a percentage and suddenly 10% to 20% sounds a whole lot more significant.

Right. 1-2 mpg sounds in significant when said that way. You're talking up to 66 extra miles PER TANK OF GAS. Over the lifetime of owning the truck that hundreds and hundreds of gallons of gas that you save on. And with gas price volatility, you're talking possible thousands of dollars saved in the long run.

 

[BowDown]

I had a 3.92 truck and purposely sought a 3.21 truck this time and have zero regrets.
After 1st gear, there's no performance advantage IMO; read the 3.21 vs 3.92 engineers thread posted above.
Now, if I was going 4x4 lifted with oversized tires, yeah I'd go with the 3.92