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

[TNRamGuy]

That's one of the best 3.21 tales yet! Beats the heck out of Prius milage!

It's about time someone justified 3.21 gears. Now I get it, it sucks to drive, sh!t$how slow, etc. But it is free to drive. Crud, it is tempting to get a 3.21 if it is free......hahahasss, nope could not do it.... I am just not that freaking secure can't wear fishnet socks or go by they/them either. But good for everythem that has 3.21, you go 'they'

 

[djevox]

It's about time someone justified 3.21 gears. Now I get it, it sucks to drive, sh!t$how slow, etc. But it is free to drive. Crud, it is tempting to get a 3.21 if it is free......hahahasss, nope could not do it.... I am just not that freaking secure can't wear fishnet socks or go by they/them either. But good for everythem that has 3.21, you go 'they'

Was that English

 

[TNRamGuy]

3.21, confused easily? , don't go all jb on me...lol

 

[theblet]

3.21, confused easily? , don't go all jb on me...lol

Don’t…..do…..it……ok….?

 

[PeteC]

My ‘22 Longhorn has 3.21 gears. I love the truck. If I cared about quickness I would have kept my ‘21 F150 Powerboost. I’m glad you all are happy with the Hemi (I am too), but it will get the doors blown off by a Powerboost, regardless of gearing on the RAM. No joke, those things are really quick. So far the engine is the only thing I miss about that F150.

 

[Mountain Whiskey]

Was that English

I'm visiting in Gatlinburg right now. I can see that since he switched from RI to TN, he is just trying to assimilate. It sounded like what passes for English here.

I think it has something to do with charcoal filtering whiskey before barreling it. Further experimentation is required though.

 

[SnowBlaZR2]

My ‘22 Longhorn has 3.21 gears. I love the truck. If I cared about quickness I would have kept my ‘21 F150 Powerboost. I’m glad you all are happy with the Hemi (I am too), but it will get the doors blown off by a Powerboost, regardless of gearing on the RAM. No joke, those things are really quick. So far the engine is the only thing I miss about that F150.

 

[PeteC]

You clearly haven’t driven one.

 

[SnowBlaZR2]

You clearly haven’t driven one.

Tested one out for a week before I bought the Ram. There are plenty of motors I miss. That isn't one of them.

 

[PeteC]

Tested one out for a week before I bought the Ram. There are plenty of motors I miss. That isn't one of them.

You are talking about a Powerboost and not the Ecoboost, right? You don’t have to miss it, but it is a more powerful engine in every category and gets far better mpg. Any stock truck it’s in is faster than any stock truck with a Hemi. These aren’t opinions, they’re verifiable facts. That being said, I traded mine in on the Hemi. I like my new truck, but having had both I believe I can say the Hemi is not the better performing of the 2 engines. Now the Ford 10 speed trans is another story. I’ve had 3 trucks with that transmission and they suck. The shifting pattern is crap, they slam into gears, and they never feel quite right. So far I’m loving the RAM 8 speed.

 

[SnowBlaZR2]

You don’t have to miss it, but it is a more powerful engine in every category and gets far better mpg. Any stock truck it’s in is faster than any stock truck with a Hemi. These aren’t opinions, they’re verifiable facts. That being said, I traded mine in on the Hemi. I like my new truck, but having had both I believe I can say the Hemi is not the better performing of the 2 engines.

If I wanted a WRX, I'd have bought a WRX. I didn't, so I bought a truck. I don't expect you to understand, coming from an EcoBoost to 3.21s.

The LS7 is a motor to miss. The 6.2 Hemi is a motor to miss. The 3.5 PowerBoost is not a motor to miss.

 

[SnowBlaZR2]

You are talking about a Powerboost

Yes. I wanted to like it because the on-board power would've been nice for dry camping.

 

[SnowBlaZR2]

Ok, there’s a miscommunication here. I didn’t say Ecoboost. I said Powerboost. It’s a Hybrid with 430Hp and 570TQ. You, in fact, have not driven a Powerboost. Most haven’t yet as they’re pretty rare. I owned a 3.5 Ecoboost before and it was comparable to the Hemi.

I, in fact, have driven one.

 

[TNRamGuy]

Was that English

I was just trying new pronouns, makes about as much sense as paying off someone else's student loans

 

[Mountain Whiskey]

I was just trying new pronouns, makes about as much sense as paying off someone else's student loans

I still think it was the liquor because I understood it when I read it last night. Now not so much.

 

[SnowBlaZR2]

Any stock truck it’s in is faster than any stock truck with a Hemi. These aren’t opinions, they’re verifiable facts.

To revisit this without the liquor, this isn't true either.

If I cared about quickness, it wouldn't be any F150.

 

[PeteC]

To revisit this without the liquor, this isn't true either.

If I cared about quickness, it wouldn't be any F150.

Quickness isn’t my top priority either, and that’s why I’m in a RAM now and I’m happy with it. Brings me all the way back to the beginning though…whether someone has the 3.21 or 3.92 gears doesn’t really matter that much for quickness. 3.92 gears have the obvious advantage there, although it doesn’t turn anyone’s truck into a race car. The real advantage is the torque multiplication when towing and there’s no comparison there.

 

[SnowBlaZR2]

Quickness isn’t my top priority either, and that’s why I’m in a RAM now and I’m happy with it. Brings me all the way back to the beginning though…whether someone has the 3.21 or 3.92 gears doesn’t really matter that much for quickness. 3.92 gears have the obvious advantage there, although it doesn’t turn anyone’s truck into a race car. The real advantage is the torque multiplication when towing and there’s no comparison there.

Those two distinct advantages with the better gears aren't mutually exclusive. I didn't go with 3.92s because they're quicker, but I'm not sad that they are either.

Still doesn't change the fact that the top Hemi is a better motor than anything the F150 has available.

 

[CrazyWorld]

Q. What is the difference between a Ford F-150 and a shopping cart?

A. A shopping cart is easier to push


Q. How do you improve the appearance of an F-150?

A. Park it between two RAMS.

 

[CatDaddy66]

I hope this post will help to end the debate with facts and not opinions, and become THE post people refer to those who are having a hard time deciding.

You already know that 3.92 is better for towing, and 3.21 gets better fuel economy, so I will talk about what you might not know

Bottom line up front:

In layman's terms, to conceptualize the difference, imagine

1) 5 out the of 8 gears have the same final drive ratio between 3.21 and 3.92.

2) 3.21 has "an extra" overdrive gear.

3) 3.21 has 2 unique lower gears for towing.

4) 3.92 has 3 unique lower gears for towing.

5) Speed range that 3.21 is better at towing: 31-38 MPH, 48-57 MPH.

6) Speed range that 3.92 is better at towing: 0-30 MPH, 39-47MPH, 58-70 MPH.


Explanation


1) 5 out the of 8 gears have the same final drive ratio between 3.21 and 3.92:

Here's the gear ratio for the 8 speed transmission:
1) 4.71:1 2) 3.14:1 3) 2.10:1 4) 1.67:1 5) 1.29:1 6) 1.00:1 7) 0.84:1 8) 0.67:1 Reverse) 3.30:1

Final drive ratios with 3.21

1st. 15.12, 2nd. 10.10, 3rd. 6.74, 4th. 5.36, 5th. 4.14, 6th. 3.21, 7th. 2.70, 8th. 2.15, R 10.6

Final drive ratios with 3.92

1st. 18.46, 2nd. 12.31, 3rd. 8.23, 4th. 6.55, 5th. 5.06, 6th. 3.92, 7th. 3.29, 8th. 2.62, R 12.94

From the list below, we can see that gears 3-7 in 3.21 matches gears 4-8 in 3.92:

-- NO MATCH -- = 18.46 - 1st - 3.92
3.21 - 1st - 15.12 = -- NO MATCH --
-- NO MATCH -- = 12.31 - 2nd - 3.92
3.21 - 2nd - 10.1 = -- NO MATCH --
-- NO MATCH -- = 8.23 - 3rd - 3.92
3.21 - 3rd - 6.74 = 6.55 - 4th - 3.92
3.21 - 4th - 5.36 = 5.06 - 5th - 3.92
3.21 - 5th - 4.14 = 3.92 - 6th - 3.92
3.21 - 6th - 3.21 = 3.29 - 7th - 3.92
3.21 - 7th - 2.70 = 2.62 - 8th - 3.92
3.21 - 8th - 2.15 = -- NO MATCH --

2) 3.21 has "an extra" overdrive gear:

The 8th gear in 3.92 is the 7th gear in 3.21, thus effectively mean the 8th gear in the 3.21 is an extra gear to the 3.92.

Meaning, when you go test drive the 3.21 you will have to downshift to 7th to get the same acceleration at 3.92's 8th on freeways. That is why some people complain about how "sloppy" the 3.21 is, because the 3.21 has an extra overdrive gear for fuel economy. If you shift 3.21 in 7th gear, you will get the same acceleration as the 3.92 in 8th on the freeway. No, 3.21 isn't sloppy, you're just in a gear that 3.92 does not have.

3) 3.21 has 2 unique lower gears for towing:

As we know from 1), 5 gears have the same final drive ratio.
You "gain" an overdrive gear, but you "lose" one towing gear.
Here's the final drive ratio for the 2 towing gears.
1st. 15.12, 2nd. 10.10,

4) 3.92 has 3 unique lower gears for towing:

Same logic as the last
Final drive for 3 towing gears.
1st. 18.46, 2nd. 12.31, 3rd. 8.23.

5) Speed range where 3.21 is better at towing: 31-38 MPH, 48-57 MPH,
AND
6) Speed range where 3.92 is better at towing: 0-30 MPH, 39-47MPH, 58-70 MPH:

Calculated towing shift point to be 6000 rpm, if I'm off the logic is the same but the speed will vary.

For towing,
From the speed 0-30 MPH, 3.92 has higher final drive ratio over 3.21 (18.46 vs 15.12) until it has to shift to 2nd gear at 30MPH.

From the speed 31-38 MPH, 3.21 has higher final drive ratio over 3.92 (15.12 vs 12.31) until it has to shift to 2nd gear at 38MPH.

From the speed 39-47 MPH, 3.92 has higher final drive ratio over 3.21 (12.31 vs 10.10) until it has to shift to 3rd gear at 47 MPH.

From the speed 48-57 MPH, 3.21 has higher final drive ratio over 3.92 (10.10 vs 8.23) until it has to shift to 3rd gear at 57 MPH.

From the speed 58-70 MPH, 3.92 has higher final drive ratio over 3.21 (8.23 vs 6.74) until it has to shift to 4th gear at 70 MPH.

The key takeaway here is that towing heavier trailers uphill with 3.21 might never reach the desired speed within the 58-70 MPH range (typical highway towing speed) because 3.21 jumps from 10.10 to 6.74 without the 8.23 final drive ratio found in 3.92 that really help maintaining highway towing speed at max load.

Do you value the "extra" overdrive gear for fuel economy? or do you value the extra towing capability that you tell yourself you might one day need? That's up to you.

I went for the 3.92 vs 3.21 not for towing but because I plan on putting larger tires, 35's, and my friend is a whiz at calculating things like that, or at least knowing where to find it on the internet. Long story short, with 35's vs stock tires and 3.92, it will essentially bring me down to a 3.55 according t0 him.