3.21 to 4.anything, but how?

VelocityC6Z · Feb 19, 2021

Looking for some advice here. Got a 2016, 8 speed 4x4 with a 3.21 gear ratio.

Everything I'm seeing is that I need to get a later model front end, and my rear end is fine to toss new gears in.

How exactly is everyone going about getting a new front end? And can anybody please give a good detailed process to go from 3.21 to 4.xx for a 2014+ ram 1500 4x4? The 3.21 is killing me, I never get on a highway more than once a year, my average speed is probably 15 miles per hour and the 3.21 gear ratio when I do get on the highway or over 40 will just be hunting for a gear with 37" tires.

Looking for some help here. Thanks team!

clint440 · Feb 19, 2021

Different approach/suggestion, but you could do a tune and LT headers. Your transmission will downshift less, and your engine will feel like it was stroked, and be snappy/responsive. Might be a cheaper and more fun way to go.

I recently towed my 24ft enclosed trailer and it pulled almost like a diesel and definitely downshifts less than stock with better mpg. Now I do have a 3.92 so not exactly apples to apples but I sometimes wish I had a 3.55 or 3.73. Never driven a 3.21 but the gearing of the ZF is pretty low starting out.

Gary2 · Feb 19, 2021

I would bet you could buy a front carrier on Ebay or scrap yard for a 13 or newer with 3.92 gears and you would probably be fine . The existing rear diff can be set up with new gears as that is a more conventional design . I would keep reading on the forum and see what others are doing . No matter what you do tuner or engine wise to increase the HP of the engine you still need to be running in the optimum rpm range to benefit from it and gears is the only thing that will do that with 37s.

pacofortacos · Feb 19, 2021

I think 3.92's front and rear complete assemblies out of a yard is by far the easiest - and honestly about the same a 4.10's in real world performance - not identical but close.

To go higher than 3.92's, I think that you need a 09-11 front assembly as the later models are welded.

Wild one · Feb 20, 2021

VelocityC6Z said:
Looking for some advice here. Got a 2016, 8 speed 4x4 with a 3.21 gear ratio.

Everything I'm seeing is that I need to get a later model front end, and my rear end is fine to toss new gears in.

How exactly is everyone going about getting a new front end? And can anybody please give a good detailed process to go from 3.21 to 4.xx for a 2014+ ram 1500 4x4? The 3.21 is killing me, I never get on a highway more than once a year, my average speed is probably 15 miles per hour and the 3.21 gear ratio when I do get on the highway or over 40 will just be hunting for a gear with 37" tires.

Looking for some help here. Thanks team!

Start hunting the wrecking yards for the front and rear diffs from a 2012 and newer truck with 3.92's,then you can swap both diffs on your driveway and sell your original diffs to recoup some of your money.As already stated by Paco to go deeper then 3.92's requires the earlier AAM diff /corresponding front driveshaft and all the brackets including motor mount to bolt it into your later ZF diff equipped truck.You'll also want to reprogram the truck for the deeper gears either by tuner or AlphaOBD etc.

crash68 · Feb 20, 2021

pacofortacos said:
I think 3.92's front and rear complete assemblies out of a yard is by far the easiest - and honestly about the same a 4.10's in real world performance - not identical but close.

^^^ this
On 37"s tires in 6th gear going 60mph:
3.92 = 2150 rpms
4.10 = 2250 rpms
Comparing both axle ratios in first gear(4.7), there is less than a difference of 1 mph at 2500 rpms

Nick@GotExhaust · Feb 21, 2021

For the front you need an 09-11 front assembly then you can change the front gears. The 13+ 3.92 idea is pretty good! If you need gears let me know we offer Yukon!

chrisbh17 · Feb 21, 2021

Like everyone else mentioned, I would just go with good condition, used factory 3.92s from a yard.

Watching all the videos on YouTube about re-gearing existing diffs, it seems like a huge PITA to get it "just right". if you dont pay a ton of money in labor, you may never know if it was done "just right". But if you buy used factory units, chances are they are at least good enough.

VelocityC6Z · Feb 21, 2021

Great suggestion, thanks everyone. I'll look into a junk yard for these in 3.92. Might even luck out with an lsd while I'm there.

ARH LT's are definitely on the list as well. Suppose those and a 3.92 setup would probably solve any issue.

Thanks y'all!

James OBrien · Feb 26, 2021

This is just a hypothetical question, but is it really that big a deal to have the 3.21 gears with the awesome 8 speed transmissions we have? I think a higher stall/custom TC would be just if not more beneficial? Just checking.

chrisbh17 · Feb 26, 2021

James OBrien said:
This is just a hypothetical question, but is it really that big a deal to have the 3.21 gears with the awesome 8 speed transmissions we have? I think a higher stall/custom TC would be just if not more beneficial? Just checking.

The higher gearing can tow more, and is more fun to drive

I dont mind my 3.21 at all, but I have also never towed anything. If I ever see myself towing regularly I would think about changing to 3.92 (or a new truck....)

Michael · Feb 26, 2021

I have the 3.21’s with the 8 speed in my truck too. I currently have 295/65/20’s on my truck now. Those are one size larger than 35’s. I would like to go to 37’s, but I know my current gearing with 37’s would make my truck worthless for anything more than just being a daily commuter. To keep my truck useful for work and pulling my TT for play I would have to change the gears to 4.56’s or something close. With the expense and hassle to change the front gears I may just skip it and also not run 37’s. I may also step down to 285/65/20’s on my next set of tires.

CheechDogg.0n37s · Feb 26, 2021

Michael said:
I have the 3.21’s with the 8 speed in my truck too. I currently have 295/65/20’s on my truck now. Those are one size larger than 35’s. I would like to go to 37’s, but I know my current gearing with 37’s would make my truck worthless for anything more than just being a daily commuter. To keep my truck useful for work and pulling my TT for play I would have to change the gears to 4.56’s or something close. With the expense and hassle to change the front gears I may just skip it and also not run 37’s. I may also step down to 285/65/20’s on my next set of tires.

For 37s you would need to gear to 4.88s like I did ...

Wild one · Feb 26, 2021

Phone number to these 4.88's,i'll phone them for ***** and giggles

CheechDogg.0n37s · Feb 26, 2021

Wild one said:
How many times do you have to be told you can't get 4.88's for the earlier AAM front diff,4.56's are the deepest you can go in a 4X4,if you read his post,you'd see he says he has a front diff.

And the shop I went to says other wise and the people I know with the 4.88s proves it ... from what I understand they can and have done it at this shop just requires a different front diff from a 2010 or older model ..

https://www.nitro-gear.com/Chrysler-9-25-Nitro-Ring-Pinion-p/c9.25-488-ng.htm

You can see that they sell the 4.88s for 4x4 ram 1500s years 1994-2010 ...and if shops here in my area are adding 4.88s that means that you are incorrect ....

Wild one · Feb 26, 2021

CAG CheechDogg said:
And the shop I went to says other wise and the people I know with the 4.88s proves it ... from what I understand they can and have done it at this shop just requires a different front diff from a 2010 or older model ..

https://www.nitro-gear.com/Chrysler-9-25-Nitro-Ring-Pinion-p/c9.25-488-ng.htm

You can see that they sell the 4.88s for 4x4 ram 1500s years 1994-2010 ...and if shops here in my area are adding 4.88s that means that you are incorrect ....

Just phoned these guys and you can only get 4.88's for the heavier 2500/3500 front diffs,4.56's is as deep as they go for the light duty 8" AAM front diff.

Nitro Gear & Axle Front & Rear Gear Package Kit for 03-10 Dodge Ram 2500/3500 | POLY PERFORMANCE

CheechDogg.0n37s · Feb 26, 2021

Wild one said:
Just phoned these guys and you can only get 4.88's for the heavier 2500/3500 front diffs,4.56's is as deep as they go for the light duty 8" AAM front diff.

Nitro Gear & Axle Front & Rear Gear Package Kit for 03-10 Dodge Ram 2500/3500 | POLY PERFORMANCE

Correct for the 8" AAM front diff ... they are switching the front diffs out in order to get those 9.25" 4.88s they have .... I just posted the link but here it goes again ....

https://www.nitro-gear.com/Chrysler-9-25-Nitro-Ring-Pinion-p/c9.25-488-ng.htm

Ask them question correctly and you will see that they are indeed putting 4.88s in the front diffs of Ram 1500s ...

Wild one · Feb 26, 2021

CAG CheechDogg said:
Correct for the 8" AAM front diff ... they are switching the front diffs out in order to get those 9.25" 4.88s they have .... I just posted the link but here it goes again ....

https://www.nitro-gear.com/Chrysler-9-25-Nitro-Ring-Pinion-p/c9.25-488-ng.htm

Ask them question correctly and you will see that they are indeed putting 4.88s in the front diffs of Ram 1500s ...

That's not the diff that's being referred to ,the diff being refernced is the light duty 8.25 AAM front diff,this is right off Nitro's site,no 4.88's listed for the front diff that's being referred to in this post or the other post.Not sure about your reading abilities there lad,as nowhere has anybody mentioned swapping to the heavier duty 3/4 ton ie: 2500 front diff. If you can point out where this post or the other post says anything about installing the 3/4 tons front diff. Maybe i missed that part,but for the life of me i don't recall that even being mentioned.There are even pic's of the diff dilligaff just bought for 300 bucks,it's not the 3/4 ton front diff.You're doing a fair bit of back pedalling now,lol

BTW thats the rear diff you're linking to,not the front diff,it's going to be mighty tuff to steer with a solid axle rear diff up front,lol

"Chrysler 8.25" Double Drilled 3.73, 4.10 and 4.56 gears"

CheechDogg.0n37s · Feb 26, 2021

I know it's not the diff that dilligaff has but people want to know if it's possible to add 4.88s for 4x4 ram 1500s which it is ... you just have to swap out the diff ... and that link I posted has the 9.25" 4.88s for the 12 bolt diff lol ... just because someone didn't mention swapping out the front diff doesn't mean "I" can say "hey you can add 4.88s" right ? .... you want to start an argument like always that is not necessary just to satisfy your bipolar self? Or what is it really? Because you seem to always want to argue with someone on the forums ....

Fact is you can in fact add 4.88s to 4x4 Ram 1500s, you just have to switch out the front diff completely ...

Wild one · Feb 26, 2021

CAG CheechDogg said:
I know it's not the diff that dilligaff has but people want to know if it's possible to add 4.88s for 4x4 ram 1500s which it is ... you just have to swap out the diff ... and that link I posted has the 9.25" 4.88s for the 12 bolt diff lol ... just because someone didn't mention swapping out the front diff doesn't mean "I" can say "hey you can add 4.88s" right ? .... you want to start an argument like always that is not necessary just to satisfy your bipolar self? Or what is it really? Because you seem to always want to argue with someone on the forums ....

Fact is you can in fact add 4.88s to 4x4 Ram 1500s, you just have to switch out the front diff completely ...

LMAO you sure back pedal alot,that link you're posting is for the solid axle front diff,not the IFS front diff at all.I want to see you put a solid axle steering diff under the front end of a 1500.
Maybe before you think you know everything,you should do a little more research,and learn what the differances are between a front IFS diff and a solid axle front diff are,lol
Good try though,lol

3.21 to 4.anything, but how?

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