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

[BowDown]

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...

I purposely sought out a 3:21 truck, no second guessing as it was the best choice for me

 

[lkjk]

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

My point is, what's the threshold...does 400 rpms more decrease engine life, or maybe it's 800, or maybe its 1000. and how much does it decrease it by? 1%? 5%? The answer is, you don't know, and I don't either, so its just anecdotal. And come on, how many of us are really going to take these things to 200-300K miles or whatever it is? probably none.

You two clearly can't imagine a world where deeper gears make sense, which is fine, but you should try to understand them better (outside of just MPGs and anecdotal engine life) before you try to convince other people who just want advice.

the last thing I'll point out is safety. Having a car that is quicker is safer. If I accidentally pull out in front of someone, the faster I can get moving or out of their way the better. There are a bunch of different examples. going from 4.10s in my jeep to 5.38s really highlighted that.

 

[KWKSLVR]

My point is, what's the threshold...does 400 rpms more decrease engine life, or maybe it's 800, or maybe its 1000. and how much does it decrease it by? 1%? 5%? The answer is, you don't know, and I don't either, so its just anecdotal. And come on, how many of us are really going to take these things to 200-300K miles or whatever it is? probably none.

You two clearly can't imagine a world where deeper gears make sense, which is fine, but you should try to understand them better (outside of just MPGs and anecdotal engine life) before you try to convince other people who just want advice.

the last thing I'll point out is safety. Having a car that is quicker is safer. If I accidentally pull out in front of someone, the faster I can get moving or out of their way the better. There are a bunch of different examples. going from 4.10s in my jeep to 5.38s really highlighted that.

True, on the speed thing but there are diminishing returns on that too, at least from a drag strip perspective. Sometimes that extra shift slows you down or too many gears keeps you out of your peak power band for as long as it could be beneficial for you to stay in it.

Balance with everything, of course.

 

[BowDown]

My point is, what's the threshold...does 400 rpms more decrease engine life, or maybe it's 800, or maybe its 1000. and how much does it decrease it by? 1%? 5%? The answer is, you don't know, and I don't either, so its just anecdotal. And come on, how many of us are really going to take these things to 200-300K miles or whatever it is? probably none.

You two clearly can't imagine a world where deeper gears make sense, which is fine, but you should try to understand them better (outside of just MPGs and anecdotal engine life) before you try to convince other people who just want advice.

the last thing I'll point out is safety. Having a car that is quicker is safer. If I accidentally pull out in front of someone, the faster I can get moving or out of their way the better. There are a bunch of different examples. going from 4.10s in my jeep to 5.38s really highlighted that.

100 rpms less will increase engine life, to what degree, IDK but I know on my car, 100 rpm can increase valve spring life significantly as well as piston ring life, it's not anecdotal.
I see no reason that these principles wouldn't apply to the truck just like they do a diesel.

I took my last truck to 277k miles so to answer your question, me.

I can perfectly understand a situation where a lower gear (numerically higher) would be beneficial, it's just not in this truck primarily because of the 8 speed trans, there's a reason hellcat redeyes don't go significantly faster with 3:09s vs the 2:71 gear, the transmission and torque, you don't need a lot of gear when you have torque, gear is a bandaid for lack of power. Example, my car with 3:42's actually has too much gear now because of the torque curve and amount.
I also know plenty of people that have put more gear in the car and lost performance, gears are a trade off, faster 100' acceleration for slower acceleration after 100' because you run out of motor/rpm.

Gears made more of an impact in 3, 4, 5 and 6 speed trans, less of an impact in 8 and 10 speed trans.

Your safety argument is just dumb, sorry. Having more gear incase you pulled out indrint of traffic will more than likely result in wheel spin which will actually you down causing an accident. A better solution would be to not pull out into traffic. Case in point, my car is on drag radials 24/7 and I still don't pull out infront of people. Even on DR's I can spin tge tires at 60 mph, that's power. Less power and more gear will do the same thing just at a slower speed.

If your in a situation where 3:92 is a significant help for you, you may need to move up to a 2500 and a diesel.

 

[BowDown]

True, on the speed thing but there are diminishing returns on that too, at least from a drag strip perspective. Sometimes that extra shift slows you down or too many gears keeps you out of your peak power band for as long as it could be beneficial for you to stay in it.

Balance with everything, of course.

Exactly, especially the powerband and shifts comment.
My car has 3:42's, would be faster with a 3.08 especially from a roll. That shift costs me a car length against a fast A10 mustsng or ZL1

 

[1awesomelaw]

Is your son going to rock crawl or build out his truck by doing a cam, super charger... in other words, does he really care about 1/10th of a second quicker? If not, 3.21 is the best ratio for 99%(*) of people out there.

(*) number pulled from my butt, not statistically measured nor tested on children under the age of 12.

Hey may or may not tow, he's going to lift it 3" high and change the wheels and tires out, not modify the engine except a custom made cold air intake. He's an electrical engineer working for Raytheon. and he already is going to change out all the speakers to infinities.

 

[silver billet]

My point is, what's the threshold...does 400 rpms more decrease engine life, or maybe it's 800, or maybe its 1000. and how much does it decrease it by? 1%? 5%? The answer is, you don't know, and I don't either, so its just anecdotal. And come on, how many of us are really going to take these things to 200-300K miles or whatever it is? probably none.

Do the math.
1000 hours at 1400 rpms = 84 million revolutions.
1000 hours at 1800 rpms = 108 million revolutions.

You two clearly can't imagine a world where deeper gears make sense, which is fine, but you should try to understand them better (outside of just MPGs and anecdotal engine life) before you try to convince other people who just want advice.

Actually it's you who has trouble here imagining anything other than your choice. I've been very clear in this thread and others; the 3.92 makes sense in rebel trim for offroading, and for guys who want to run bigger tires; and for that mythical tow truck in work trim with a high enough payload to actually to more than 8000 pounds if you feel the rest of the truck is well suited to the load (which I don't, past 8000 pounds you're better off in a 2500).

the last thing I'll point out is safety. Having a car that is quicker is safer.

If a fraction of a second quicker (only from a dead stop, it doesn't apply 20 to 40 for example) was actually one of your reasons then you sure picked the wrong choice as Ram is slower than pretty much any Ford and the GM 6.2. Ah, but you don't like those trucks so you were willing to sacrifce a whole second slower 0 to 60 (in the case of the Ford) to get your preferred truck, but it's somehow a bad idea for us in the 3.21 to sacrifice an additional fraction.... Right....

 

[lkjk]

You guys know that one about talking to a wall? Anyways, glad we have the world's foremost experts on gears on this forum.

Anyone want to buy a 1500? Pros: low miles. Cons: will probably self destruct at 80K miles and you'll have to fill up 2 more times per year than everyone else. I give you special price.

 

[silver billet]

You guys know that one about talking to a wall? Anyways, glad we have the world's foremost experts on gears on this forum.

Anyone want to buy a 1500? Pros: low miles. Cons: will probably self destruct at 80K miles and you'll have to fill up 2 more times per year than everyone else. I give you special price.

Oh everyone should jump all over that deal, us 3.21 guys are just driving little wife and baby killers over here, can't imagine how much safer I'd feel with the 3.92 knowing I can acclerate from a stop sooooo much faster.

 

[1awesomelaw]

Gee Whiskey, you sure are worried about your uh, "manhood" Compensating perhaps?

A tip for you, grab the 3.21 to save hundreds each year on gas and extend the life of your hemi.... and for your manhood problem, just roll with the mirrors flipped out.

I have no issues with my manhood , my ram has the 3.21 gears, my son didn't know what to purchase himself.
And Mirrors flipped up look-Gay might as well be driving a ford...

 

[Hasti17]

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

Better wiper fluid.

 

[Hasti17]

Maybe i was born yesterday
But It almost seems like ram put two ratios in trucks...
I think im onto something so follow me along here, it LOOKS like ram made one optimized for higher towing Cap, And one optimized for fuel efficiency.
Pick your preference.

You wanna go faster? Buy a TRX. Wanna save more money on gas? Pick up a prius.
Wanna argue over made up reasons for why your trucks better?
Grab a ruler and your partner, and go measure each other in A public bathroom to settle it once and for all.

 

[nc_beagle]

I have no issues with my manhood , my ram has the 3.21 gears, my son didn't know what to purchase himself.
And Mirrors flipped up look-Gay might as well be driving a ford...

Based on a lot of MountainWhiskey's other posts, he often posts things tongue in cheek. The kind of joking that doesn't translate well to the internet since you can't see a grin--without using the smilies.

 

[HSKR R/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

View attachment 104112

I take my Ram to the drag strip and race it. No it's not fast, but drag racing isn't always about being the fastest. Depending on what class you are running, with bracket racing, it's just about consistency and knowing your vehicle. If you are only worried about being the fastest out there, you will always be disappointed. There is always going to be someone with more money, or more time, making more power. And my actual "Track toy" is also a truck. It's just broken right now. 00 Dakota R/T that I was spraying 200 shot into a built engine. And it still wasn't "fast" by current standards, but I was consistent.

 

[BowDown]

I take my Ram to the drag strip and race it. No it's not fast, but drag racing isn't always about being the fastest. Depending on what class you are running, with bracket racing, it's just about consistency and knowing your vehicle. If you are only worried about being the fastest out there, you will always be disappointed. There is always going to be someone with more money, or more time, making more power. And my actual "Track toy" is also a truck. It's just broken right now. 00 Dakota R/T that I was spraying 200 shot into a built engine. And it still wasn't "fast" by current standards, but I was consistent.

Too many sand-baggers bracket racing, got no time for that. i'm a mod then race then mod some more to go faster guy. Dont really care what the other lane does, I'm trying to run 9's N/A and run the same car on a road course the next weekend

 

[HSKR R/T]

Too many sand-baggers bracket racing, got no time for that. i'm a mod then race then mod some more to go faster guy. Dont really care what the other lane does, I'm trying to run 9's N/A and run the same car on a road course the next weekend

I usually just go to test and tune nights. Easy to weed out the sand baggers. Just have to run your dial in. And they will either break out trying to beat you, or lose

 

[theblet]

Neither ratio is “better” than the other. There’s two options. Get the one you prefer and be happy with your vehicle. Not sure what all the debate is about.

 

[Redfour5]

My point is, what's the threshold...does 400 rpms more decrease engine life, or maybe it's 800, or maybe its 1000. and how much does it decrease it by? 1%? 5%? The answer is, you don't know, and I don't either, so its just anecdotal. And come on, how many of us are really going to take these things to 200-300K miles or whatever it is? probably none.

You two clearly can't imagine a world where deeper gears make sense, which is fine, but you should try to understand them better (outside of just MPGs and anecdotal engine life) before you try to convince other people who just want advice.

the last thing I'll point out is safety. Having a car that is quicker is safer. If I accidentally pull out in front of someone, the faster I can get moving or out of their way the better. There are a bunch of different examples. going from 4.10s in my jeep to 5.38s really highlighted that.

Rippums seem less important now days. four bangers and Fords with smaller engines turbocharged are always working high rpms but some of em run for hundreds of thousands of miles (e.g. toyotas). But I must admit the Ford "ecoboost" always SEEMED to be pushing the envelope on trucks... A big steel V8 sure SEEMS more robust over time...unless you get the Hemi Tick...

 

[Scram1500]

Neither ratio is “better” than the other. There’s two options. Get the one you prefer and be happy with your vehicle. Not sure what all the debate is about.

The debate is over the correlation between tallywhacker and gear ratio

 

[BowDown]

Neither ratio is “better” than the other. There’s two options. Get the one you prefer and be happy with your vehicle. Not sure what all the debate is about.

The debate is over the correlation between tallywhacker and gear ratio

I thought that was settled 10 pages ago?