What's involved in a 3:21 to 3.92 upgrade on 2019 Ram 1500

[CharlieZ]

Good morning folks. First post on this platform, please be kind.
Looking at a sweet deal on a 2019 Ram 1500 Sport with lots of trimmings...but not the 3.92. I usually haul ~8000lbs for over 2000km to go moose hunting, so i think the 3.21 wouldn't cut it (blew up an ecodiesel this fall in the middle of nowhere which is a story for another day!). I found a slightly used 3.92 with anti-slip at a local wrecker at a decent price. Do i need to change anything else, like the transfer case, TCU update...? Couldn't find anything on youtube. I would really appreciate some advice from someone who's done this.
Much appreciated.

 

[danielmid]

If it's a 4x4 you'd need the front diff from the wrecker also

 

[GTyankee]

the front & rear gear ratio must be the same

I think that you can remove the front drive shaft, until such time as you feel good about the way it drives with the the 3.92 conversion
Then at a later date, you can convert the front differential & reconnect the drive shaft

Good Luck

 

[18CrewDually]

the front & rear gear ratio must be the same

If it's a 4x4 you'd need the front diff from the wrecker also

FACTS

 

[ThunderMug95]

Yeah, its just a gear swap in the rear, but the front is the whole differential. Junkers are usually a grand or so. I have 3.21’s, wish I had 3.92’s. But honestly with an 8speed you overcome a lot of the difference. Im choosing a tune versus the gear swap. If I happened upon a front diff though, I’d do it.

 

[ThunderMug95]

the front & rear gear ratio must be the same

I think that you can remove the front drive shaft, until such time as you feel good about the way it drives with the the 3.92 conversion
Then at a later date, you can convert the front differential & reconnect the drive shaft

Good Luck

I had an employee of mine pull the CV shafts out of his AWD Mountaineer. He decided that RWD was all he really needed and his MPG would be improved. His house is on a hill. When he went to leave for work the next day, his suv was in the ditch across the street.

 

[DILLIGAF]

Just do a 3.92 gear swap. Way simpler then swapping out axles.

 

[pacofortacos]

How is a gear swap easier than an axle swap?
Axle takes a fraction of the time and in the front isn't the gear welded?
Plus is you might be able to sell the 3.21 axle and get some of your $$ back.

 

[ThunderMug95]

How is a gear swap easier than an axle swap?
Axle takes a fraction of the time and in the front isn't the gear welded?
Plus is you might be able to sell the 3.21 axle and get some of your $$ back.

You have only 1 option on the front. Complete diff swap. The rear you do have the option of digging into the pumpkin or swap it out.

 

[Rlaf75]

Like already mentioned, if it's 4x4, the entire front differential will need to be changed too. Also if I'm not mistaken the computer will need to be flashed for the correct speedometer reading too

 

[392DevilDog]

It is not worth it with the 8spd transmission.

But, have fun.

 

[DILLIGAF]

How is a gear swap easier than an axle swap?

Because you can get rid of the POS gen 4 front diff like the cool kids

I rather rebuild them with fresh new parts. You never know what kind of garbage you' ll get from a wrecker.

 

[pacofortacos]

haha
True, I always hope that they haven't drained it yet so you can get at least a little idea of the condition.

 

[stormcom]

Put in 7th gear. same output ratio as a 3.92 in 8th gear. Look at the charts.

 

[Bandit1859]

Good morning folks. First post on this platform, please be kind.
Looking at a sweet deal on a 2019 Ram 1500 Sport with lots of trimmings...but not the 3.92. I usually haul ~8000lbs for over 2000km to go moose hunting, so i think the 3.21 wouldn't cut it (blew up an ecodiesel this fall in the middle of nowhere which is a story for another day!). I found a slightly used 3.92 with anti-slip at a local wrecker at a decent price. Do i need to change anything else, like the transfer case, TCU update...? Couldn't find anything on youtube. I would really appreciate some advice from someone who's done this.
Much appreciated.

I would not do it. Lots of work to do correctly. I have a 392 and a321 on two different year trucks. About 200rpm difference at 70 mph

 

[Wild one]

Hell i'm 62,and i swapped both front and rear diffs on my driveway by myself using nothing more then a floorjack and cordless impact gun. 2 guys could easily swap both diffs on a driveway in an afternoon,if you're 1 guy give yourself most of the day.Only time you need to mess with the computor is if you change tire sizes,the wheel speed is picked up by the wheel sensors on each wheel. You can also drive around with-out any of the 4X4 pieces ahead of the transfer case with no issues,and no the front wheels won't fall,you'll get a bunch of misinformed people telling you the front wheels will fall off if you remove the front CV's. The front hubs on a 4X4 and a 2wheel drive truck are identical,including part numbers. My 4X4 hasn't had a front diff/CV's or front driveshaft for several years now

 

[Zoe Saldana]

Good morning folks. First post on this platform, please be kind.
Looking at a sweet deal on a 2019 Ram 1500 Sport with lots of trimmings...but not the 3.92. I usually haul ~8000lbs for over 2000km to go moose hunting, so i think the 3.21 wouldn't cut it (blew up an ecodiesel this fall in the middle of nowhere which is a story for another day!). I found a slightly used 3.92 with anti-slip at a local wrecker at a decent price. Do i need to change anything else, like the transfer case, TCU update...? Couldn't find anything on youtube. I would really appreciate some advice from someone who's done this.
Much appreciated.

All that for 1 Moose a year?

The gears get you moving.

Shoot the Moose; put in bet and know you will get moving slower for a little bit.

You won't break anything.

If you change gears; you will pay for the gears and pay at the pump for lower mpg all the time.

 

[Gooseit]

I have a 2015 2-wheel drive Ram with hemi and 8 speed trans. I changed the gearing from the 3:21 to the 3:92. The best thing I ever did. I hate to disagree with the one who said that with the 8 speed it would not be worth it. It made a BIG difference in performance. I bought a ring and pinion set and had my mechanic install it. At 70 mph it increased rpm by about 500rpms. Dropped gas mileage a little but well worth it. Good luck.
Gooseit

 

[392DevilDog]

I have a 2015 2-wheel drive Ram with hemi and 8 speed trans. I changed the gearing from the 3:21 to the 3:92. The best thing I ever did. I hate to disagree with the one who said that with the 8 speed it would not be worth it. It made a BIG difference in performance. I bought a ring and pinion set and had my mechanic install it. At 70 mph it increased rpm by about 500rpms. Dropped gas mileage a little but well worth it. Good luck.
Gooseit

in a 2wd, sure, it might be worth it. for what he is doing and on a 4wd, I stand by the not worth it.

 

[CLECSoft]

Good morning folks. First post on this platform, please be kind.
Looking at a sweet deal on a 2019 Ram 1500 Sport with lots of trimmings...but not the 3.92. I usually haul ~8000lbs for over 2000km to go moose hunting,

The 7th gear of 3.21 is same effective ration as 8th gear with 3.92.
I would just max out in 7th and you should be fine. The torque converter will still lock up so there shouldn't be any heating issues.
Anyone else try that?