3.21. vs 3.92 gear

Joeyp

Well-Known Member
Messages
464
Reaction score
101
Points
43
Location
Jersey Shore
So i found someone who can do it but the problem is the front diff has welds which makes if very difficult to change the gear and pinion. The cheapest option is to replace the hole front end housing with the 3.92 but that from the factory only currently and cost 1400. So in total its 2500-3000 to change it over without doing some janky stuff. I'm only wanting it to run 35s and do some lighter towing so

so I found someone who can do it but the problem is the front diff has some welds which makes it almost impossible to change the gear and pinion. The best option is to buy a new housing from ram but they are running $1400. So in total for both axles I’m looking 2500-3000 installed without doing some janky stuff to the front end. I’m only wanting to change because I’m running 35’s and still want to tow some light stuff but for that much I’ll wait to see if it gets cheaper or I’ll just keep what I got
That stinks
 

NDanecker

Active Member
Messages
79
Reaction score
81
Points
18
Location
NJ
So i found someone who can do it but the problem is the front diff has welds which makes if very difficult to change the gear and pinion.
Although I have not taken apart a 2019 RAM front diff that makes absolutely no sense and question any service department that makes said statement. I'd get a 2nd or 3rd opinion and at minimum stay clear of whomever made that statement.

I've done a bunch of gears on AAM axles, Ford 8.8 and 9", GM 10 bolt including front independent suspensions 4x4. None of them are welded shut so they cannot be disassembled.
 

riccnick

Ram Guru
Messages
912
Reaction score
759
Points
93
Location
Southwest Florida
Although I have not taken apart a 2019 RAM front diff that makes absolutely no sense and question any service department that makes said statement. I'd get a 2nd or 3rd opinion and at minimum stay clear of whomever made that statement.

I've done a bunch of gears on AAM axles, Ford 8.8 and 9", GM 10 bolt including front independent suspensions 4x4. None of them are welded shut so they cannot be disassembled.
I'm wondering if the pinion is welded in place at assembly and FCA buys the whole thing as a unit... That's the only thing I could think of that would prevent a teardown. Even then I'm stretching the imagination a bit, lol. It should be a completely bolt together type thing... How the hell do they expect to service it. Anyone on here find the 2019 Service Manuals yet?
 

SColang22

Well-Known Member
Messages
281
Reaction score
122
Points
43
Although I have not taken apart a 2019 RAM front diff that makes absolutely no sense and question any service department that makes said statement. I'd get a 2nd or 3rd opinion and at minimum stay clear of whomever made that statement.

I've done a bunch of gears on AAM axles, Ford 8.8 and 9", GM 10 bolt including front independent suspensions 4x4. None of them are welded shut so they cannot be disassembled.
It’s not that they are welded shut it’s just the way they put the front end together it’s a huge pain. I’m not super tech savvy with them but so far I got 4 shops all saying the same thing. The front ends are a huge pain and it’s best to find a used one or order the new one. Either way to rich for my blood for a small performance gain
 

2wd

Active Member
Messages
99
Reaction score
92
Points
18
Sanity check before folks go and gear swap or trade their trucks in.

6 or 7 years ago you would absolutely be correct in that you do not want the numerically lower gear if you had plans for towing heavy. Back then we were running 5 and 6 speed transmissions. These new 8/10 speed transmissions are game changers and significantly bridge the gap between rear end ratios. I would only consider a gear swap on these new Rams if I was swapping to huge tires, pulling out stumps, or just had to have the faster off the line acceleration.

For towing, unless you're the rare Ram owner who has an option light (high payload) model and tow solo with nothing in the truck, you'll never reach the 3.92 max tow rating before overloading. If you're towing realistic half ton pickup trailer loads of 5-8k, I highly recommend you try out the 3.21's before you swap.

There are not a lot of towing reports on the 3.21 to reference. Take a look at this F150 V8 5.0 (very similar HP/Torque/Power curves to the Hemi 5.7).


The Ford has 3.55 gears w/ the 6 speed and killed it on a very difficult towing test in the Rockies towing 9000 lbs. Now compare the gear by gear mechanical advantage of the Ford 6R80 w/3.55 to the Ram ZF8 w/3.21.

---- Ford Ram
1st 14.80 15.09
2nd 8.31 10.05
3rd 5.40 6.74
4th 4.05 5.36
5th 3.05 4.14
6th 2.45 3.21

The Ram with the 3.21's is putting more power (and engine braking downhill) to the wheels than this F150 in every gear. My point is the Ram 1500 with 3.21's offers improved towing performance compared to this F150 w/3.55's (a great towing truck - and truth be told it also outperforms vs Ford 3.73's).

If that performance by the Ford was just too slow up the mountain for you by all means swap your gears out (but go to 4.10's if you're going to the trouble).
 
Last edited:

Todd

Active Member
Messages
72
Reaction score
51
Points
18
Location
Central NC
Sanity check before folks go and gear swap or trade their trucks in.

6 or 7 years ago you would absolutely be correct in that you do not want the numerically lower gear if you had plans for towing heavy. Back then we were running 5 and 6 speed transmissions. These new 8/10 speed transmissions are game changers and significantly bridge the gap between rear end ratios. I would only consider a gear swap on these new Rams if I was swapping to huge tires, pulling out stumps, or just had to have the faster off the line acceleration.

For towing, unless you're the rare Ram owner who has an option light (high payload) model and tow solo with nothing in the truck, you'll never reach the 3.92 max tow rating before overloading. If you're towing realistic half ton pickup trailer loads of 5-8k, I highly recommend you try out the 3.21's before you swap.

There are not a lot of towing reports on the 3.21 to reference. Take a look at this F150 V8 5.0 (very similar HP/Torque/Power curves to the Hemi 5.7).


The Ford has 3.55 gears w/ the 6 speed and killed it on a very difficult towing test in the Rockies towing 9000 lbs. Now compare the gear by gear mechanical advantage of the Ford 6R80 w/3.55 to the Ram ZF8 w/3.21.

---- Ford Ram
1st 14.80 15.09
2nd 8.31 10.05
3rd 5.40 6.74
4th 4.05 5.36
5th 3.05 4.14
6th 2.45 3.21

The Ram with the 3.21's is putting more power (and engine braking downhill) to the wheels than this F150 in every gear. My point is the Ram 1500 with 3.21's offers improved towing performance compared to this F150 w/3.55's (a great towing truck - and truth be told it also outperforms vs Ford 3.73's).

If that performance by the Ford was just too slow up the mountain for you by all means swap your gears out (but go to 4.10's if you're going to the trouble).
Great information posted 2wd !
 
  • Like
Reactions: 2wd

NDanecker

Active Member
Messages
79
Reaction score
81
Points
18
Location
NJ
It’s not that they are welded shut it’s just the way they put the front end together it’s a huge pain. I’m not super tech savvy with them but so far I got 4 shops all saying the same thing. The front ends are a huge pain and it’s best to find a used one or order the new one. Either way to rich for my blood for a small performance gain
Clarification noted. Thanks! :)

I agree that an IFS axle housing is a pain to swap. The whole unit needs to come down unlike a conventional axle where you pull the cover and disassemble while the axle is still in the truck. The term 'welded shut' got me running down a path I didn't want to believe thus my post. LOL
 

Johnvan

Active Member
Messages
90
Reaction score
84
Points
18
I used to tow my 6000lb trailer with an Infiniti Qx56. It had very similar specs. 5.7 liter V8, 400 hp, 413 lbs torque and a 7 speed transmission. Axle ratio was 2.73! It did exceptionally well. I pulled up some pretty steep grades and still had plenty of power in reserve.
I would think that the 3.21 would have no trouble.
 
  • Like
Reactions: 2wd

SColang22

Well-Known Member
Messages
281
Reaction score
122
Points
43
Sanity check before folks go and gear swap or trade their trucks in.

6 or 7 years ago you would absolutely be correct in that you do not want the numerically lower gear if you had plans for towing heavy. Back then we were running 5 and 6 speed transmissions. These new 8/10 speed transmissions are game changers and significantly bridge the gap between rear end ratios. I would only consider a gear swap on these new Rams if I was swapping to huge tires, pulling out stumps, or just had to have the faster off the line acceleration.

For towing, unless you're the rare Ram owner who has an option light (high payload) model and tow solo with nothing in the truck, you'll never reach the 3.92 max tow rating before overloading. If you're towing realistic half ton pickup trailer loads of 5-8k, I highly recommend you try out the 3.21's before you swap.

There are not a lot of towing reports on the 3.21 to reference. Take a look at this F150 V8 5.0 (very similar HP/Torque/Power curves to the Hemi 5.7).


The Ford has 3.55 gears w/ the 6 speed and killed it on a very difficult towing test in the Rockies towing 9000 lbs. Now compare the gear by gear mechanical advantage of the Ford 6R80 w/3.55 to the Ram ZF8 w/3.21.

---- Ford Ram
1st 14.80 15.09
2nd 8.31 10.05
3rd 5.40 6.74
4th 4.05 5.36
5th 3.05 4.14
6th 2.45 3.21

The Ram with the 3.21's is putting more power (and engine braking downhill) to the wheels than this F150 in every gear. My point is the Ram 1500 with 3.21's offers improved towing performance compared to this F150 w/3.55's (a great towing truck - and truth be told it also outperforms vs Ford 3.73's).

If that performance by the Ford was just too slow up the mountain for you by all means swap your gears out (but go to 4.10's if you're going to the trouble).
I was looking at it because I'm running bigger tires and pulling. For sure have thought it all out and I am well aware the 8 speed is a better transmission but even without towing there is a huge power loss with the 3.21 by running 35's. I am down shifting hard to maintain speed up even slight grades. The money isn't worth the swap right now so I'm sticking with performance upgrades and a tune. I'll see how that works and if not ill probably still swap gears.
 
  • Like
Reactions: 2wd

NordicNevs

Well-Known Member
Messages
270
Reaction score
343
Points
63
Great thread. Strictly talking number here I wanted to chime in...I have the 3.21 ratio and I am coming from a 3.42 in the 3500 Cummins and the 3.73 in the Duramax. I have logged in 10,000s miles towing with my diesels. However, the point of payload is an invaluable one. My truck has 1850# payload and 8500# towing. If you think about tongue weight to trailer weight properly loaded...the math is about perfect for the PL to TW ratios. Now take the same 1850# PL and make the trailer capability at 11,500#....you are now tongue light and trailer heavy. My 2500 Chevy had 2300# payload but 17,xxx trailering....I am telling you with any conventional, gooseneck or 5er you will not hit those numbers and be under the payload numbers. I will say there is one exception that I can think of that will give you the 3k extra weight without the increase in payload and that will be a high end aluminum trailer ($$$$$$). In general, my seat of the pants and confidence in the 3.21 is there all day long to get up to and almost touch the max towing while being safely within my payload, with my family and our gear.
 

chad202

Well-Known Member
Messages
207
Reaction score
118
Points
43
just pulled my boat from south Louisiana to Toledo bend. Pulled in tow/haul with not issues. Down shifted sometimes but only one gear. Fuel mileage was 14-15mpg. The following week went to Dallas without pulling boat, just me, wife and luggage. Set cruise tween 75-80 and averaged 20-21. This is with hills and windy. I have the 3.21s and think they are great.
 

2wd

Active Member
Messages
99
Reaction score
92
Points
18
I was looking at it because I'm running bigger tires and pulling. For sure have thought it all out and I am well aware the 8 speed is a better transmission but even without towing there is a huge power loss with the 3.21 by running 35's. I am down shifting hard to maintain speed up even slight grades. The money isn't worth the swap right now so I'm sticking with performance upgrades and a tune. I'll see how that works and if not ill probably still swap gears.
Right on - Bigger tires like you're describing is another story and upgrading may be totally worthwhile. I was providing some evidence to folks who are looking to swap purely for towing on stock size wheels.

Two other things to consider. There are tuners out there that are plug and play that really boost the performance (like Pulsar). Could be worth a look (I don't have any experience).

If you're going to do the gear swap, you may want to checkout RamForums.com in the 4thGen section. They are not the exact same trucks, but the Engine/Transmissions are the same I think since 2013. You may find some folks there that have gone to 4.10 (or higher) gears with big tires posting feedback after a swap. Could be worth considering if you're investime the time and money.
 

SColang22

Well-Known Member
Messages
281
Reaction score
122
Points
43
Right on - Bigger tires like you're describing is another story and upgrading may be totally worthwhile. I was providing some evidence to folks who are looking to swap purely for towing on stock size wheels.

Two other things to consider. There are tuners out there that are plug and play that really boost the performance (like Pulsar). Could be worth a look (I don't have any experience).

If you're going to do the gear swap, you may want to checkout RamForums.com in the 4thGen section. They are not the exact same trucks, but the Engine/Transmissions are the same I think since 2013. You may find some folks there that have gone to 4.10 (or higher) gears with big tires posting feedback after a swap. Could be worth considering if you're investime the time and money.
I have a pulsar and it’s okay. If you are looking for a tune without unlocking the pcm it’s a good option. I’m waiting for the trinity 2 to come out for the 19s and go with a Jay Greene tune. Also may drop down to 33’s.
 

SColang22

Well-Known Member
Messages
281
Reaction score
122
Points
43
just pulled my boat from south Louisiana to Toledo bend. Pulled in tow/haul with not issues. Down shifted sometimes but only one gear. Fuel mileage was 14-15mpg. The following week went to Dallas without pulling boat, just me, wife and luggage. Set cruise tween 75-80 and averaged 20-21. This is with hills and windy. I have the 3.21s and think they are great.
I would agree if your running stock tires. Once you go bigger it’s a huge difference
 

metalmancpa

New Member
Messages
1
Reaction score
1
Points
3
Interesting read. I have 2,700 miles now on my '19 Crew running stock 55/20's with 3.92 ratio. I am right around 16 mpg average. I tow a trailer that's 2,000 lbs loaded. The gas mileage is not great, and the 3.92 came with the truck with options I searched for. Honestly was only hoping to avg 17 mpg in the truck so I guess I'm 1 mpg disappointed.
 

3275 Mbrown

New Member
Messages
1
Reaction score
2
Points
1
I’m looking to place an order and I’m not sure of which gear ratio to order. 95% of the time I will be driving the truck empty. Gas mileage is important to me so I’m ordering the e-torque engine. I tow a small trailer that weighs 4000 lbs and only do it 6-8 weekends a year.

My concern is that the 3.92 gear is going to kill the gas mileage. The 3.21 just seems a bit low for a truck of this size.

Looking for the mpg difference between the two in every day driving.

Thanks
I just purchased a 2019 Ram Limited with 3:92 gears and my sons 2019 Ram Laramie with 3:21 gears.
While tacking 2,000 rpm my truck is running 72 mph. My sons truck is running 84 mph at 2,000 rpms.
I do feel the torque difference.
I guess it’s all about what you are going to use your truck for.
 

Zeronet

Well-Known Member
Messages
409
Reaction score
359
Points
63
Based on the usage you described, if mpg is important, you don’t plan to go with bigger tires and you travel at highway speeds frequently then the 3.21 is the better fit.
 

Eyecutter98

Member
Messages
9
Reaction score
3
Points
3
New to board. Looking to buy and this board is great! Thx!
I wanted 3.92 gearing with 5.7V8 etorque but very hard to find with other features I’m wanting. I don’t haul much. Just wanted for more off the line get up and go. About to give up and get 3.21 from frustration. Do y’all think it matters for someone not towing? Could I tell the difference?
 

79 300

Active Member
Messages
153
Reaction score
105
Points
43
I test drove a 3.92 before I ordered mine with the 3.21 anti-spin. In normal driving you probably won't notice a difference.
The 3.21 has more than enough get- up and go in my opinion. My previous truck was a 2500 with the 5.7 so this truck seems very quick by comparison.
 

JDBob35a

Active Member
Messages
92
Reaction score
77
Points
18
Location
Missouri
This has been discussed a lot, you can use the search and find all the reading you'll want. But here's my two cents.
I have the 3:21, I pull a 20' boat every weekend and it will almost jerk the trailer out from under it if you want it to. Runs great down the road and plenty of power to get you tickets. The 8 speed trans really helps overcome the higher gearing.
Buddy of mine has the 3:92, I can tell it's a little quicker off the line, but he's also not getting quite as good of MPG as my truck. (Neither of us have ETorque.)
Plenty of opinions on here about this subject. Some say not enough diff in MPG so go with 3:92, I'm on the other side, I'll take the little extra mpg and still has plenty of towing capability for anything I do.
I also pull an enclosed trailer with a vette in it, will a 3:92 get it rolling quicker? "Yes", does the 3:21 struggle with it "no".
Bottom line, - I'd say if you found a truck at the price you want, with the other options you want, forget the gears if you aren't towing all the time.
 

Users Who Are Viewing This Thread (Users: 0, Guests: 3)

Top