3.21 vs 3.92 real world

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ramffml

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The actual ratio changes a bit below 6th gear between the two rear gear ratios.
What you state is true for 6th gear and up only.

There is a similar thing going on for most of the gears, though 6th and 7th is definitely the closest match. But you're missing the point. If 3.21 is in 4th and 3.92 is in 6th, whose truck is putting more power down?

Essentially when it comes to the specific choice between 3.21 and 3.92, you gain a lower gear and lose an overdrive with the rest being so close it's not even worth worrying about.
 

pacofortacos

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The biggest difference between the 3.21 and the 3.92 is over 60 mph the 3.21 will start to deliver superior mpg.

If most of your driving is under 60 mph (esp. if most is 45-50 mph), the 3.92 imo offers a smoother superior driver experience as it is in 8th gear as low as 40 mph. So you will use 8, 7, 6 in most all normal driving above 40 mph - honestly I am very seldom down to 6 at 45 mph unless it's a hill. Those 3 gears are all a fairly close ratio, below 6th gear the spread gets larger and a 3.21 will most likely use 7, 6, 5th gears in that scenario.

The amount of power put down between the 2 gears in different transmission gears but at an equal overall ratio will be about the same as the power put down is what is required to move the truck at the desired speed.

It isn't a huge difference and I agree not worth worrying about unless like me most of your driving is over 70+ mph.

I had a Pacifica that really would have been much more pleasant to drive with a deeper gear. It had the 9 speed and I almost never was in 9th gear - even over 74 mph, and when it did go in, it couldn't hold it. But from idle to 60 it was ok, but just not right. The van would have been much more pleasant to drive if it would have had a deeper gear that would have put all of the 9 speeds just one gear down - ie. 9th gear being used where currently 8th was. Hard to explain but easy to understand if you had ever driven one.
 

ramffml

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The biggest difference between the 3.21 and the 3.92 is over 60 mph the 3.21 will start to deliver superior mpg.

If most of your driving is under 60 mph (esp. if most is 45-50 mph), the 3.92 imo offers a smoother superior driver experience as it is in 8th gear as low as 40 mph. So you will use 8, 7, 6 in most all normal driving above 40 mph - honestly I am very seldom down to 6 at 45 mph unless it's a hill. Those 3 gears are all a fairly close ratio, below 6th gear the spread gets larger and a 3.21 will most likely use 7, 6, 5th gears in that scenario.

The amount of power put down between the 2 gears in different transmission gears but at an equal overall ratio will be about the same as the power put down is what is required to move the truck at the desired speed.

It isn't a huge difference and I agree not worth worrying about unless like me most of your driving is over 70+ mph.

I had a Pacifica that really would have been much more pleasant to drive with a deeper gear. It had the 9 speed and I almost never was in 9th gear - even over 74 mph, and when it did go in, it couldn't hold it. But from idle to 60 it was ok, but just not right. The van would have been much more pleasant to drive if it would have had a deeper gear that would have put all of the 9 speeds just one gear down - ie. 9th gear being used where currently 8th was. Hard to explain but easy to understand if you had ever driven one.

The biggest difference is from a dead stop, and when the 3.21 is in 8th (which you mentioned re: 60 mph).

Beyond that, there is no difference. No difference in smoothness. No difference in power. No difference in MPG. They are literally in the same gear ratio.

As I said before, 2 * 4 = 8 is the same as 4 * 2 = 8. Your rear end is "bigger" but you essentially end up using a smaller transmission gear so it's the same thing.

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pacofortacos

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The biggest difference is from a dead stop, and when the 3.21 is in 8th (which you mentioned re: 60 mph).

Beyond that, there is no difference. No difference in smoothness. No difference in power. No difference in MPG. They are literally in the same gear ratio.

As I said before, 2 * 4 = 8 is the same as 4 * 2 = 8. Your rear end is "bigger" but you essentially end up using a smaller transmission gear so it's the same thing.

View attachment 501924
Except, most people don't just drive at 45 or 60 mph all of the time. Most start and stop, many go up and down hills, many drive in 35 mph zones.
IMO, the overall driving experience below 50-60 mph and in varying speeds below those speeds is somewhat nicer in the 3.92 geared truck. It isn't a large difference and not worth choosing one ratio over the other but it does exist.

Say we are driving at 25-30 mph (25 mph zones are common where I live), I am in 4th gear, you are in 3rd gear both at about the same ratio. However up ahead is a decent hill, I downshift to 3rd gear, yours has to go to 2nd gear. My change is 6.74 to 8.39, your truck goes from a 6.87 to a 10.27. I think a ratio change of 1.65 is going to be a bit smoother than your 3.4.

At static speeds with a static load there isn't really any difference as you say. I don't live in a static world.

It isn't as pronounced as the Pacifica scenario, but it's not like it doesn't exist.
 

ramffml

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Except, most people don't just drive at 45 or 60 mph all of the time. Most start and stop, many go up and down hills, many drive in 35 mph zones.
IMO, the overall driving experience below 50-60 mph and in varying speeds below those speeds is somewhat nicer in the 3.92 geared truck. It isn't a large difference and not worth choosing one ratio over the other but it does exist.

Say we are driving at 25-30 mph (25 mph zones are common where I live), I am in 4th gear, you are in 3rd gear both at about the same ratio. However up ahead is a decent hill, I downshift to 3rd gear, yours has to go to 2nd gear. My change is 6.74 to 8.39, your truck goes from a 6.87 to a 10.27. I think a ratio change of 1.65 is going to be a bit smoother than your 3.4.

At static speeds with a static load there isn't really any difference as you say. I don't live in a static world.

It isn't as pronounced as the Pacifica scenario, but it's not like it doesn't exist.

Yes, well we can all cherry pick exact speeds where one truck might be slightly nicer than the other; what happens when we're driving at the speed where your truck just gets into second but mine is still in first? You need to downshift because you're "lugging" when you hit that special hill but I'm still revving quite high and motoring on .... etc etc.

We can do that for very specific speeds and hills, but the point is that's not real life. In real life, it's all a wash. When I'm easy on the pedal, the RPM range is like 400 rpms between shifts. None of that up/down shifting is jarring, busy, jolting, or even "noticeable" for that matter unless you're looking for it. This truck is buttery smooth!

Edit: like the other poster in this thread, I'm going to bow out of this discussion as I've said it all a million times now and we'll either agree or not.

Enjoy your ram, I'd be happy with a 3.92 as well. It's just the wrong gear ratio for me where my truck spends 98% of it's non-idling time in 8th gear.
 

pacofortacos

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It does depend on where you live and your driving. Your truck is good for your situation.
Where I live all we have is specific speeds and hills - hills everywhere - very little 65-70 mph zones but a lot of 25, 35, 45, a few 55 zones.
I'm out of first gear by 4-5 mph, so unless we are cruising at 10 mph, there is no downshifting to 1st in normal operation.

Honestly, since my truck is mainly used for highway trips, I have often wished for 3.21 gears - just for the mpg over 70 mph.
Or better yet, the current 8 with 1 or 2 more overdrives gears lol.

I have said that there is very little difference and not worth picking one over the other in "normal' driving - but to not acknowledge that there is a slight difference is just not reality.
 

mikepol2

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Just got back from a 160 mile highway trip, one way, and reset the trip computer when I started out. Mostly with cruise set at 77 mph, but lots of construction where it was 60. According to the trip computer I averaged 19.1 mpg. About 3-1/2 hrs, all highway except about the first 10 and last 10 minutes.

Caveat 1: I removed the foam/mesh screen from inside the air intake box and am using an Airaid dry flow filter. I've seen some folks in the air intake threads commenting that their mpg dropped 1-2 mpg after installing their Mopar intakes. During another all-highway trip that was pre-air intake mods but only about 20 miles, I averaged 21 mpg.

Caveat 2: There is about a 1,000 foot elevation change from the start of the trip to the end. So it was slightly uphill the whole way.
 
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