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

[Idahoktm]

I never thought a gear discussion could turn into an oil thread.

 

[BowDown]

I agree 100%. I've never understood the average truck driver that drives like they're in a sports car. You're not. It's not fast. Even a TRX is not all that blazing fast (please bear in mind I come from a background where a respectable quarter mile is high 11's).

Maybe I'm just not in a hurry anymore and I burned it all out of my system when I was a dumb teenager/20 something. I leave on time and get where I'm going early and routinely catch up to pedal to the floor trucks a few red lights later anyway.

I also routinely coax more mpg out of my vehicles than the EPA estimates. It matters to me, especially on long road trips.

100% agree. I'm not interested in this truck being fast because it never will be and anyone thinking a 3:92 truck is fast is delusional. If I want fast, I get in my car, a few minutes in it and everything else is slow, almost time going in reverse slow .

Its funny to see some of these pro 3:92 comments yet they go over here and complain about mileage

Anyone else happy with MPG?

I am not too happy with the MPG on this truck. Just shy of 2k miles on it so far with mostly city driving and I'm averaging about 10.3 mpg. Not getting on it or anything. The 17 year old F150 I traded in was getting about 17mpg in town. Although it did have a small V8 with the 4.6L But...

5thgenrams.com

Poor gas mileage

I've seen reports of others getting poor gas mileage in their 5th Generation Rams. Mine is horrible. Has anyone else gotten a dealer to figure out what's wrong with this truck? I've had my truck in the shop twice now for this issue. The Ram technicians are not able to find anything wrong with...

5thgenrams.com

 

[Rlaf75]

These rams are mostly a 4 door pickup trucks not a Corvette. You want fast you buy a sportscar. You want fuel efficiency you buy a lil 4 cylinder car. The difference in gears ratios in our trucks is because of towing and hauling capabilities. They arent for quarter mile times. Most people will never use these trucks to their full potential and most of us keep our trucks basically stock so the ratios wont matter much. I get almost the same exact gas mileage out of my 21 BTS with an 8spd and 3.21 gears as I got from my 11 bighorn 5spd with 3.55 gears. Yeah the 3.92 may be quicker off the line than the 3.21 gears but who the hell drag races these things off every traffic they're at?

 

[BowDown]

These rams are mostly a 4 door pickup trucks not a Corvette. You want fast you buy a sportscar. You want fuel efficiency you buy a lil 4 cylinder car. The difference in gears ratios in our trucks is because of towing and hauling capabilities. They arent for quarter mile times. Most people will never use these trucks to their full potential and most of us keep our trucks basically stock so the ratios wont matter much. I get almost the same exact gas mileage out of my 21 BTS with an 8spd and 3.21 gears as I got from my 11 bighorn 5spd with 3.55 gears. Yeah the 3.92 may be quicker off the line than the 3.21 gears but who the hell drag races these things off every traffic they're at?

Exactly. 3:92's no doubt make towing easier from a dead stop. 60' later the advantage is gone

 

[Idahoktm]

It's funny how "snappier acceleration" = drag racing to the the 3.21 lovers. Good gawd you guys are dramatic.

 

[Rlaf75]

It's funny how "snappier acceleration" = drag racing to the the 3.21 lovers. Good gawd you guys are dramatic.

What's even funnier is the fact the 3.92 lovers think they are far superior at a certain thing when after a certain point there isn't much difference at all. Like someone mentioned earlier, it's like a "which oil is better" thread. And I highly doubt real world gas mileage will be much different between the to ratios either. Who really cares how much more "snappier" one is over the other unless you are drag racing and need to get to the finish line first. In real world driving there wont be much of a difference

 

[BowDown]

It's funny how "snappier acceleration" = drag racing to the the 3.21 lovers. Good gawd you guys are dramatic.

You should re-read, thats an attribute the 3:92 geared people use

 

[silver billet]

The only benefit of 3.21s vs 3.92s is mpg, at the expense of performance. The reason people care about MPG is because of the associated expense, ignoring the hassle factor of stopping for fuel.

Actually one of the main draws for me is that my engine is just idling its way through life. Since my truck lives in 8th, and can do it so effortlessly, what is the point in running around with 400 rpms higher? Just to pull a trailer that weighs 3000 pounds more than my truck can pull but wait only it can't because both trucks are payload limited?

There is no real difference in performance.

Rock crawlers (rebel) and bigger tires are the only real reasons. The rest of you are just burning extra fuel needlessly.

Why stop at 3.92? Why not run 5.10s?

 

[silver billet]

It's funny how "snappier acceleration" = drag racing to the the 3.21 lovers. Good gawd you guys are dramatic.

This thread was done 35 pages ago, all we've had since then is drama but yet here we all are. Clearly its still interesting.

 

[Eighty]

 

[KWKSLVR]

How much weight are people actually pulling anyway? If you were really pulling that max with 3.92 gears I doubt you could say the truck felt safe and stable doing it.

 

[silver billet]

Besides, us 3.21 guys can just install a pedal monster and boom; snappy performance. Check mate.

 

[Idahoktm]

What's even funnier is the fact the 3.92 lovers think they are far superior at a certain thing when after a certain point there isn't much difference at all. Like someone mentioned earlier, it's like a "which oil is better" thread. And I highly doubt real world gas mileage will be much different between the to ratios either. Who really cares how much more "snappier" one is over the other unless you are drag racing and need to get to the finish line first. In real world driving there wont be much of a difference

I'm the one that compared it to an oil thread.

I care about 3.92 being snappier... that's why I ordered it. I tested both ratios and like 3.92 better. I don't drag race, I just prefer 3.92. It's as simple as that. Why anyone would care about me liking 3.92 over 3.21 is amusing. I never mentioned a word about 3.92 being superior to 3.21 either. All I did was post the reasons I like 3.92.

 

[lkjk]

Actually one of the main draws for me is that my engine is just idling its way through life. Since my truck lives in 8th, and can do it so effortlessly, what is the point in running around with 400 rpms higher? Just to pull a trailer that weighs 3000 pounds more than my truck can pull but wait only it can't because both trucks are payload limited?

There is no real difference in performance.

Rock crawlers (rebel) and bigger tires are the only real reasons. The rest of you are just burning extra fuel needlessly.

Why stop at 3.92? Why not run 5.10s?

Who cares if its running 400 rpms higher? there's no proof that 400 rpm more, or 800, or whatever magic number it is will prolong engine life.

And performance meaning turning bigger/heavier tires, in the mtns, and not so sluggish from dead stop. I'm not racing my truck and don't care about that.

And you're right, why stop at 3.92s. My jeep has 5.38s in it, massive difference over the 4.10s, or even the non-rubi ratios. It is slow, but you can instantly tell the performance difference it made, on road, not racing.

My point is if you can afford a truck that costs 40-70K, saving a few hundred bucks a year for objectively worse performance (mentioned above, nothing to do with speed or racing) seems strange.

I would agree with you if those savings were more meaningful, say $1000+ per year, but they aren't.

 

[silver billet]

Who cares if its running 400 rpms higher? there's no proof that 400 rpm more, or 800, or whatever magic number it is will prolong engine life.

Who cares if it's a 10th slower to 60 at WOT? We can play this game for hours. An engine that spins less lasts longer (all else being the same), that's simply physics.

And performance meaning turning bigger/heavier tires, in the mtns, and not so sluggish from dead stop. I'm not racing my truck and don't care about that.

And you're right, why stop at 3.92s. My jeep has 5.38s in it, massive difference over the 4.10s, or even the non-rubi ratios. It is slow, but you can instantly tell the performance difference it made, on road, not racing.

My point is if you can afford a truck that costs 40-70K, saving a few hundred bucks a year for objectively worse performance (mentioned above, nothing to do with speed or racing) seems strange.

It's less about "saving money" and more about "not wasting money for no reason". The reason you don't have 5.38's on your Ram is because you know its pointless. There is a point where a low rear gears means you just are just needlessly waisting gas, and that point is the 3.21 in our truck with the 8 speed. The engine provides piles of torque to handle our 8th gear on the freeway, so at that point you don't need lower gears.

 

[Rlaf75]

I'm the one that compared it to an oil thread.

I care about 3.92 being snappier... that's why I ordered it. I tested both ratios and like 3.92 better. I don't drag race, I just prefer 3.92. It's as simple as that. Why anyone would care about me liking 3.92 over 3.21 is amusing. I never mentioned a word about 3.92 being superior to 3.21 either. All I did was post the reasons I like 3.92.

Ok Good for you.

 

[BowDown]

Who cares if its running 400 rpms higher? there's no proof that 400 rpm more, or 800, or whatever magic number it is will prolong engine life.

And performance meaning turning bigger/heavier tires, in the mtns, and not so sluggish from dead stop. I'm not racing my truck and don't care about that.

And you're right, why stop at 3.92s. My jeep has 5.38s in it, massive difference over the 4.10s, or even the non-rubi ratios. It is slow, but you can instantly tell the performance difference it made, on road, not racing.

My point is if you can afford a truck that costs 40-70K, saving a few hundred bucks a year for objectively worse performance (mentioned above, nothing to do with speed or racing) seems strange.

I would agree with you if those savings were more meaningful, say $1000+ per year, but they aren't.

It's kinda common sense, lower rpm, less engine wear ergo longer life.
Ever wonder why diesels live so long? Yeah, low rpms.

As for saving a few bucks and worse performance, this is a 5500lb truck, I didn't buy it for performance nor will the 3:92's make me say holy S this thing is fast.
I have a 10 sec, 700 hp N/A Z06, nothing you can to this truck will make it fast or seem fast. All I expect from this truck is luxury and semi decent fuel mileage. It's also not a prius do I fo not expect 30+ mpg but I do want the best mileage I can get from it; it also tows my car just fine

 

[Eighty]

Ever wonder why diesels live so long? Yeah, low rpms

Probably has to do with the quality of oil used. Let’s discuss.

 

[oldsouth]

Maybe that's why Ram offers different ratios. You can order what you want. Pleases two different groups of people. No need in trying to prove to the other group why you like your ratio or why you think it's better. Just be happy with what you chose. No one wants to second guess their choice, hence the bickering. But really you are thinking.... Did I get the best one... Lol...

 

[BowDown]

Probably has to do with the quality of oil used. Let’s discuss.

Mineral oil is the sh*t but I use a mineral olive oil blend for that extra edge