3.21 or 3.92

[WadXpress]

I love my 8 speed with the 3.21s especially once you throw the hemifever tune on it. It's no slouch off the line. I can break them loose whenever I want

 

[CMil527]

I love my 8 speed with the 3.21s especially once you throw the hemifever tune on it. It's no slouch off the line. I can break them loose whenever I want

nice rig!

 

[saintsreturn]

Well congrats on the purchase. I have the 8spd with the 3.21's installed. I plan on towing a weighted truck and trailer to florida in 13 months and then a 26ft boat. We will see if a gear swap is coming up or just the enjoyment of the truck

 

[CFDRAM4257]

Hey so I'm a newbie to the site. How do you tell what gears you have? I'm not sure what mine are

 

[QwikKota]

Check your build sheet online. Add your VIN to the end of this: http://www.dodge.com/webselfservice/BuildSheetServlet?vin=

 

[BULL55]

I have the 5.7 Hemi 8 speed, 3.21 rear end. The truck 4X4 pulls fine and eats fords and chevy trucks with ease so far on the road rage inter- state heats. I did not buy it as a a race truck but, I am impressed with the 8 speed and 5.7!

 

[SlowRoller]

What little I've towed, I'll say,,, while in 7th,,, the 8 speed 3.21 in my 14 runs approx. the same RPM/pulls like 5th gear did in my 09 5 speed with 3.92's,,

I only had about 3k total load spread out between riders/cargo/small trailer. Hit 'tow/haul' and it purrs along in 7th just fine,, Almost identical RPM to the 09 w/3.92 in 5 of 5.

If I towed 24/7, or towed heavier loads, perhaps the 3.92's would be advantageous,,,,,,

In my case, I tow 'light' a couple times a year. 3.21's w/8 speed are the bee's knee's for my application. 3.92's would be overkill. (As my screen-name implies, I'm not a racer,,,)

 

[NorthTexasHemi]

I am in a rental RAM 1500 Hemi with 3.21 as my truck (3.92) is in the body shop. The milage is much better with the 3.21 (about 4 mpg better) but it is not as much fun to drive. The rental has 17" wheels vs the 20's on my truck so it feels more bouncy to me maybe a little less responsive. Not sure on that, I'll get a better feel after a few more days.

 

[QwikKota]

4mpg seems a bit outlandish. I would think two trucks would need several months for a fair comparison.

 

[05christj]

Your truck is not even close to being in the same league as a hemi with the 8 speed and 3.21. You should go drive both with the 8 speed then you would know what the 3.21 guys are saying.

I never said it was, the man asked for an opinion and I gave mine.

We all know the difference between the 4.7 and 5.7 is a world of difference.

 

[CFDRAM4257]

So I just found out from that build sheet website that my truck has 3.55s. What do you think would 3.92s make a big difference? I tow a utility trailer every week. Not everyday but atleast two or three times a week.

 

[clh1220]

I never said it was, the man asked for an opinion and I gave mine.

We all know the difference between the 4.7 and 5.7 is a world of difference.

Oh **** it looks like I offended you. Now the op did ask for a opinion. So why don't you go back and read his post. He wanted to know about a hemi and 8 speed 3.92 and 3.21. So I'm glad you know the difference between the trucks. That's why I said what I did to you because your opponion didn't make sense. In this case. Too many people in these forums give advice about something they don't have.

 

[NorthTexasHemi]

4mpg seems a bit outlandish. I would think two trucks would need several months for a fair comparison.

I'll have this truck for 2-3 weeks, so far I am getting much better milage with the 3.21 but there is not as much get up and go. I think this about as fair as a test as can be done. Is it a perfect test, nope but I like that I am able to test it out with as close to my daily driver doing the same routine driving I usually do. Maybe the rental being a quad cab vs my crew cab being heavier is affecting the MPG. I am not driving any different and drive the same 56 miles everyday.

 

[QwikKota]

So I just found out from that build sheet website that my truck has 3.55s. What do you think would 3.92s make a big difference? I tow a utility trailer every week. Not everyday but atleast two or three times a week.

I was not aware of 3.55's being available with the Hemi and 8speed. That would be the perfect combo IMO. Definitely not available in 2015 or I would have selected that. 3.92's sound like overkill for any trailers under 6k lbs.

 

[CFDRAM4257]

Ok my bad I didn't say the tranny! I have 6 speed and 3.55s. Think 392s are worth it? I unfortunately do tow quite frequently.

 

[clh1220]

Ok my bad I didn't say the tranny! I have 6 speed and 3.55s. Think 392s are worth it? I unfortunately do tow quite frequently.

If it's a 4wd for sure it's not worth it. It wouldn't be worth it to me if it was 2wd either.

 

[audio1der]

Ok my bad I didn't say the tranny! I have 6 speed and 3.55s. Think 392s are worth it? I unfortunately do tow quite frequently.

As mentioned below, 4x4 adds a lot of cost when changing gears. If you're going to do this I would step up to 4.10s to make a difference.
I would have chosen 4.10s if they were a factory option.

 

[MurderHemi]

I have a 8 speed reg cab with 3:92's and it has A LOT of gear. It is fun though. I didn't buy the truck to tow though. I am sure it will if I have to. Truck is a 2wd and is stock for now. With that gearing my truck only stays in ECO mode until about 65mph. Here is a 0-70 run I made at the end of last year.

https://youtu.be/qqKhXmxNBX4

 

[EagleChief]

I skipped pages 2-5... But, I say go for the 3.92's. I drove a 3.21 geared truck and could definitely tell a difference. After that, wasn't even an option for me. I don't pull a trailer, but maybe a couple of times per year. I get 17-18 mpg's combined highway/city (usually 75-80 mph on the highway). If I keep the truck under 2k rpms, mileage goes way up. The 3.92 gears are just too good to pass up, honestly. Really not sure why you wouldn't get them. The mpg's aren't that big of a difference.