[gregs2018ram]

I have the 3.92 and my RPM's still sit in the 1500's going 65mph.

Does peak to about 1800 at 75.

I have noticed about a 1-1.5 mph decrease (versus a 17 Express with 3.21)

With the 3.21, continual gear hunting in 7-8. 3.92 seems to stay in 8th until you get down around 45 or so.

If you don't tow, you're better off with the 3.21. That's what I have and I absolutely love it.

Power to spare, and engine RPMs stay very low (better MPG).

Cheers,
Neurobit

 

[Thunderhorse]

I have the 3.92 and my RPM's still sit in the 1500's going 65mph.

Does peak to about 1800 at 75.

I have noticed about a 1-1.5 mph decrease (versus a 17 Express with 3.21)

With the 3.21, continual gear hunting in 7-8. 3.92 seems to stay in 8th until you get down around 45 or so.

If its hunting 7-8 due to load or terrain or whatever, you shoukd use ERS to lock out 8, that's what its for.

3.21s don't hit 2000 RPM in 8th gear until about 90 MPH

 

[gregs2018ram]

No one was talking about hitting 2000RPM in a 3.21. where did you come up with that statistic?

the point was that the 3.21 reaches 8th too fast, then only shifts back to 7th or 6th

If its hunting 7-8 due to load or terrain or whatever, you shoukd use ERS to lock out 8, that's what its for.

3.21s don't hit 2000 RPM in 8th gear until about 90 MPH

 

[Thunderhorse]

No one was talking about hitting 2000RPM in a 3.21. where did you come up with that statistic?

You mentioned 1800 at 75 with 3.92s

I came up with it by looking at my tach when my speedometer needle is at 90.

The shift point for 3.21s seems to be 55mph minimum to go into 8th under light/no load. It will shift back to 7th at 50 minimum

 

[pacofortacos]

I am still trying to figure out how he is only hitting 1800 rpms at 75 mph, pretty sure mine is 2000 rpms @ 75 or real close to it. I do know my speedometer is dead nut accurate too.

 

[Thunderhorse]

I am still trying to figure out how he is only hitting 1800 rpms at 75 mph, pretty sure mine is 2000 rpms @ 75 or real close to it. I do know my speedometer is dead nut accurate too.

Tire size?

 

[jakkaxe]

I am still trying to figure out how he is only hitting 1800 rpms at 75 mph, pretty sure mine is 2000 rpms @ 75 or real close to it. I do know my speedometer is dead nut accurate too.

Here's a pic of mine at 76. 22" wheels and the 3.21 axle. By the look of it I'd say closer to 1700. This was on a relatively flat road.

 

[pacofortacos]

Here's a pic of mine at 76. 22" wheels and the 3.21 axle. By the look of it I'd say closer to 1700. This was on a relatively flat road.

I have the 3.92's so mine is a few hundred rpms higher.
I like the 3.92's for everyday driving, they are perfect for 55 and under, but wish I had a 9th gear for 73+ mph. LOL

 

[mmullengs]

not sure if the 3.55 is still available but , i had that in my 2011 and it was a nice middle of the road compromise i now have the 3.92 in my 2014 and find that it is quite handy for towing

 

[Neurobit]

Here's a pic of mine at 76. 22" wheels and the 3.21 axle. By the look of it I'd say closer to 1700. This was on a relatively flat road.

Yeah, looks like mine. I believe I was doing around 1700 at 75 MPH. I'll try to take a pic next time I jump on a Fwy, which isn't often (and why I avg around 9-10 MPG in town).

 

[Thunderhorse]

not sure if the 3.55 is still available but , i had that in my 2011 and it was a nice middle of the road compromise i now have the 3.92 in my 2014 and find that it is quite handy for towing

There were a few 8 speed 3.55s made in 2013, but for the most part they kanked the option when the 8 speeds came out. With the 5 and 6 speed there was about a ton difference in capacity between 3.21 and 3.55 and another ton or so between 3.55 and 3.92. With the 8 speed the spread closed to around 1000 lbs between 3.21 and 3.55 and 3.55 to 3.92. They probably dropped it because of the minimal difference.

I drove my dad's 5 speed 3.21 Ram when I was in AZ in April, and my truck pulls waaaaaayyy harder off the line

 

[pacofortacos]

I would have went for 3.55 over 3.92 in a heartbeat. Not sure why it isn't even an option, there just isn't any real reason that I can think of.

 

[Ramajama]

3.92 all day, every day.

 

[Thunderhorse]

3.92 all day, every day.

You have 4.10s though

 

[DarkKn1ght]

3.92's all the way. My '04 had 3.92's and I wouldn't have it any other way unless I could go steeper. Heck, my Jeep has 4.88's.

 

[Thunderhorse]

3.92's all the way. My '04 had 3.92's and I wouldn't have it any other way unless I could go steeper. Heck, my Jeep has 4.88's.

But it also had a 5 speed.

Diff gears are only half of the final drive ratio equation

 

[Riller]

Love having the 3.92 gears and limited slip. Don't do much towing, but it really helps up and down the mountains here in NC.

 

[George1953]

Have 2015 Ram 1500 Outdoorsman 4x4 with crew cab, 5.7 ft box, 3.55 gears, limited slip differential, 3.6 V6 & towing package. Better towing vs 3.23 gears. Better mileage towing than 3.92 gears. Getting 14 mpg pulling 3,300 lb. 20 ft. travel trailer on I4/FL at 65 to 70 mph. Door sticker toe rating 6,800 lbs.

 

[Thunderhorse]

3.92 gears aren't even an option for V6 (gas) trucks

 

[Redfour5]

Have 2015 Ram 1500 Outdoorsman 4x4 with crew cab, 5.7 ft box, 3.55 gears, limited slip differential, 3.6 V6 & towing package. Better towing vs 3.23 gears. Better mileage towing than 3.92 gears. Getting 14 mpg pulling 3,300 lb. 20 ft. travel trailer on I4/FL at 65 to 70 mph. Door sticker toe rating 6,800 lbs.

I have the same vehicle with the 5.7 and 3.92 gears. I don't get 14 mpg regular driving and 9ish when pulling a 22 foot TT. In retrospect, if I had a choice, I would have gone with your set up.

I had a 13 quad cab with the old tranny, 5.7 and the 3.55 gears and to be honest, it would kick you back in the seat better than the 8 speed which is a bit more civilized in how it takes off. Passing on 70 mph two lanes in MT is my comparison point. Oh, it got roughly the same mpg as the 8 speed with the 3.92 gears.

Irrespective, I do like my truck. I just suck it up on the gas.