3.22 Gear Swap to 3.92 Grocery List

[Algunz]

Here's the story:

I'm currently running 35s on my 6in lift but want to upgrade to 37s..

My main concern is power loss and serious trans wear with adding the 37s.. my 35s weigh 69 lbs and the 37s I'm looking at are between 75-80 lbs, I doubt its a good idea to keep the 3.22s with the additional weight.

I just want gears that can handle the tires DECENT without me having to worry about serious wear on the trans and total crap highway performance.

I understand 4.56 is the way to go but the cost is not worth it to me. I think the 3.92 on top of the 8 speed will be enough for my needs. I only drive on the highway 2-3 times/month. Most of the rest of my travel is traffic lights 30-50mph roads.

I would like to just swap out my front diff with a 3.92 ram diff and replace the rear gears and call it a day.


This is what I found so far on my to buy list:

http://www.moes-performance.com/OEM_3_92_Gears_9_25ZF_Rear_Axle_2011_up_Ram_1500_p/oem392.htm

https://www.ebay.com/itm/13-17-DODG...=item25fe86c95c:g:zAAAAOSwKdZbZMRe:rk:21:pf:0

Are these the only two components I need to get this done?


I know I'm beating a dead horse here with this topic, but knowing I'm on the verge of pulling the trigger and doing this, I want to be sure I'm doing it the right way and getting the correct parts.

Any guidance or direction would be appreciated.

 

[McBroom]

Here's the story:

I'm currently running 35s on my 6in lift but want to upgrade to 37s..

My main concern is power loss and serious trans wear with adding the 37s.. my 35s weigh 69 lbs and the 37s I'm looking at are between 75-80 lbs, I doubt its a good idea to keep the 3.22s with the additional weight.

I just want gears that can handle the tires DECENT without me having to worry about serious wear on the trans and total crap highway performance.

I understand 4.56 is the way to go but the cost is not worth it to me. I think the 3.92 on top of the 8 speed will be enough for my needs. I only drive on the highway 2-3 times/month. Most of the rest of my travel is traffic lights 30-50mph roads.

I would like to just swap out my front diff with a 3.92 ram diff and replace the rear gears and call it a day.


This is what I found so far on my to buy list:

http://www.moes-performance.com/OEM_3_92_Gears_9_25ZF_Rear_Axle_2011_up_Ram_1500_p/oem392.htm

https://www.ebay.com/itm/13-17-DODG...=item25fe86c95c:g:zAAAAOSwKdZbZMRe:rk:21:pf:0

Are these the only two components I need to get this done?


I know I'm beating a dead horse here with this topic, but knowing I'm on the verge of pulling the trigger and doing this, I want to be sure I'm doing it the right way and getting the correct parts.

Any guidance or direction would be appreciated.

Don’t forget the install kit for the rear end. And idk about the front.


I love my truck!
Blue Mule 18 Ram 2500 4x4 C/C Off Road.

 

[Algunz]

Don’t forget the install kit for the rear end. And idk about the front.

So the rear gear and axle isnt enough? Do you know what comes with the install kit? I will start searching for them

 

[Algunz]

NVM I just saw for an additional $99 you can get install kit

 

[McBroom]

So the rear gear and axle isnt enough? Do you know what comes with the install kit? I will start searching for them

It’ll have bearings,races,seals, probably the shims(if not do not let them get out of the stack or on the opposite sides of the housing.
The kit should also have some gear marker fluid (tube)
And will also include the most important part the crush sleeve.


I love my truck!
Blue Mule 18 Ram 2500 4x4 C/C Off Road.

 

[Navy Six Zero]

Am curious to see how this ends up, pls follow up.

 

[Silver Goose]

Algunz, are you going to be doing the work? A lot of work, setting the tooth depth and such. The last diff I setup was forty years ago so maybe it has gotten easy with the install kit.

Will the suspension be up to the task or will you need to change shocks/springs or both. Don't forget to readjust your computer for speed change.

Good Luck

Larry

 

[Algunz]

Algunz, are you going to be doing the work? A lot of work, setting the tooth depth and such. The last diff I setup was forty years ago so maybe it has gotten easy with the install kit.

Will the suspension be up to the task or will you need to change shocks/springs or both. Don't forget to readjust your computer for speed change.

Good Luck

Larry

I'm having a shop do all of the work, I would never mess with the gearing myself, Although the front diff swap doesnt seem like too much of a daunting task.

Having said that, I did not realize the suspension would have to be changed for a diff swap and gear swap? What exactly do I need to be concerned about with the suspension here?

Am curious to see how this ends up, pls follow up.

Still waiting for my shop to quote me out and then going to schedule sometime in February. Will keep the thread posted.

 

[PoMansRam]

It's amazing how cheap a lower final drive ratio is when you buy brand new vs what it would cost to retrofit the truck later on. Just today my brother bought a 2019 Classic Express QC, 4x4, pentastar. The "upgrade" from 3.21's to 3.55 was $95 on the sticker.

 

[Wild one]

I'm having a shop do all of the work, I would never mess with the gearing myself, Although the front diff swap doesnt seem like too much of a daunting task.

Having said that, I did not realize the suspension would have to be changed for a diff swap and gear swap? What exactly do I need to be concerned about with the suspension here?



Still waiting for my shop to quote me out and then going to schedule sometime in February. Will keep the thread posted.

You don't have to change your suspension for a gear swap. You'll need to do something with the speedo when you go to the 37" tires,but you don't have to do anything to it for just a gear swap.The speedo reads off the outer ABS sensors,and the only thing that affects it,is changing tire sizes.

 

[crackerjack1957]

You don't have to change your suspension for a gear swap. You'll need to do something with the speedo when you go to the 37" tires,but you don't have to do anything to it for just a gear swap.The speedo reads off the outer ABS sensors,and the only thing that affects it,is changing tire sizes.

Had to change gear ratio on BCM from 3.55 to 4.56 on mine......@ WOT the transmission wasn't shifting at set rpm.....inconsistent.....maybe 6-speed related only

 

[pacofortacos]

Why not buy the front and rear complete assemblies used from a wrecking yard?
By far the easiest way to do it and often the least expensive - if you can find them.

 

[Algunz]

It's amazing how cheap a lower final drive ratio is when you buy brand new vs what it would cost to retrofit the truck later on. Just today my brother bought a 2019 Classic Express QC, 4x4, pentastar. The "upgrade" from 3.21's to 3.55 was $95 on the sticker.

Truth be told. I know now for when I get my next truck. This was my first truck and didnt even think about bigger tires or a lift because the truck was so much taller than my old passat. Fast forward a year and want bigger tires and more height, should have done the gear homework when shopping trucks... you live you learn I guess lol

You don't have to change your suspension for a gear swap. You'll need to do something with the speedo when you go to the 37" tires,but you don't have to do anything to it for just a gear swap.The speedo reads off the outer ABS sensors,and the only thing that affects it,is changing tire sizes.

Thanks for clarifying. I was thinking of getting one of the calibrators to reconfigure the speedometer with the change in tire size

 

[Algunz]

Why not buy the front and rear complete assemblies used from a wrecking yard?
By far the easiest way to do it and often the least expensive - if you can find them.

It's not a bad idea... that will definitely save me a hefty sum on labor charges. I was looking at them online and they appeared all used and rusty, unlike mine that has fluid film applied every year since I had it.. I prefer not to sacrifice part quality just to get the 3.92 gears, but worth checking the wrecking yard absolutely. Just need to find one within reasonable distance to me..

 

[pacofortacos]

If they are good on the inside is what counts, you could make the outside pretty before installing

 

[indept]

As far as tire size correction, see the 4th Gen DIY section of this forum. In the AlfaOBD thread, you can update it yourself.

 

[Quyonmob]

Not going to 4.56 will leave you with lots of regret. The 8 spd’s double overdrives want deeper gears.

3.92 and 37’s will make little use of 8th gear. You aren’t going to lose mpg by going to 4.56 over 3.92 with 37’s, that’s for sure.

I’m looking to go to 4.11 with 265/70/17.

 

[radkawi]

All you need is a front diff carrier and a rear gear set with install kit. Some fluids for both and maybe a fastener or two depending on if you hog them up but that's it.
I bought a front diff w/3.92 from a bone yard and so happy I did. The dealer part is just too much for what it is. I then purchased an OE 3.92 rear gear set. Negotiated with and had the dealer install both right after I added the lift. I have to say I really noticed little difference in day to day operation however, when towing, the 3.92s make the grade and was well worth with the investment. Slightly higher RPMs at speed but that is to be expected.
I recently used Alpha to change the tire diameter to calibrate speedo which helped a bit on the trans shift performance but would like to be able to change the ratio from the 3.21 the factory has in the BCM. Currently this change is not supported in the Alpha software but have been informed by the developer that is in the works. Don't know if it'll make a difference in anything but would like it changed none the less. The dealer cannot help us with this after 2011.
Not sure how you'd get to 4.11 or 4.56 in the front as I am unaware of anyone servicing parts for the later model front diffs so if you find them I'd say get 'em, you'll be glad you did.
Don't fret over the 3.92 change if you can't get one of the others and have the disposable coin for when you add that extra unsprung weight you'll notice it. Maybe not as much having the 8 speed but there will be a noticeable difference. That HEMI and the 8 speed combo is well thought out and has the grit to move the metal even with 35s and 3.21s.
Best of luck with your build and enjoy it!

 

[Wild one]

Not going to 4.56 will leave you with lots of regret. The 8 spd’s double overdrives want deeper gears.

3.92 and 37’s will make little use of 8th gear. You aren’t going to lose mpg by going to 4.56 over 3.92 with 37’s, that’s for sure.

I’m looking to go to 4.11 with 265/70/17.

You'll need to hunt up the earlier AAM 8.25 front diff / front driveshaft and corresponding brackets to bolt it in,as they never made a 4.11 or deeper front diff in the ZF front diffs.You have 3 options with the ZF front diff and that's 3.21 / 3.55 and 3.92's anything other then those 3 ratio's means you'll need the earlier diff,as the gears are not swappable in the ZF front diffs.

 

[Quyonmob]

You'll need to hunt up the earlier AAM 8.25 front diff / front driveshaft and corresponding brackets to bolt it in,as they never made a 4.11 or deeper front diff in the ZF front diffs.You have 3 options with the ZF front diff and that's 3.21 / 3.55 and 3.92's anything other then those 3 ratio's means you'll need the earlier diff,as the gears are not swappable in the ZF front diffs.

Fugg sakes, I was wondering why all my searches were coming up dry. Might go back to GM, at least there are gears and carriers available...