4.56 Gearing...is it necessary? Ongoing research project.

[@JC]

My PW has 35" Nitto RGs and I wish it had 3.73 gearing instead of the 4.10, only drawback to the tire swap was the extra 27lbs per tire from the stock Duratracs. I wouldn't have ordered my 392 with the XR package even if it would have been available and 35x12.5r17 Nitto RGs are going on it as soon as it arrives, it will be just fine.

 

[Battle.Rattle]

I have 35s on my 392. I live at altitude and the transmission has no problem staying in 8th. 3.73 is perfect for 35s on a 392. I had 4.10 on the 3.6 with with 34s, it was an absolute dog here at altitude, I never went to 35s because it wasn’t livable with the 34s. 4.56 is good for 37s or 39s. Totally not needed for a 35s 392, on and off road.

Did you have to recalibrate when you went up to 35s?

 

[stumblinhorse]

Did you have to recalibrate when you went up to 35s?

You don’t “have to”. Not off by that much really. Usually from the factory the speedo runs high. And depending on the tire you get it might be a small 35.

I did recalibrate using my method which is very precise. I get diameter by driving a mile or so measuring the distance via GPS and adjust tire size setting up or down to get that exact distance after resetting the trip. Takes a few miles…

 

[Rjezonie]

The way my mind works if the XR has 4.56 with 35’s, if I go 37’s I should run 4.88s.

Might be too much, but we’ll see. So far it’s just a battle between the “4.56 is great” crowd and the “why regear? It runs fine” crowd. The debate is maddening (and, ultimately no help when you realize it’s just all opinion wars with no hard data, just anecdotal evidence.

So much tribal knowledge out there from people who have been there and done that, but I really don’t know who to believe so I’m just doing my thing…..4.88’s and 37s. If I don’t like them, honestly I may just dial up the coil overs to 5” lift, get some flat fenders, and go to 40s.

Literally no difference in stability with the 37s vs the 33s.

I love my 392 on 37s with 4.88s! Night and day difference!

 

[Rjezonie]

Get the 4.88s for 37s…especially when adding weight and lifting it!

 

[justinB]

Gearing Advice Please!!!

My non XR 392 w/3.73 gears is at the dealership now. Swung by last night and they said to leave it and they would take a look at it today. My rear electronic locker messed up (I Think). It was making a clucking noise only when turning at slow speeds and when switching on/engaging 4 low it does not mechanically engage. The idiot light came on as well.

Anyways, the service manager said that sometimes when the e-locker fails they have to replace more than just the locker. They may have to replace the gears... and sometimes the entire axle, dependent upon how much damage 'spread around' inside the housing. Makes sense if the locker's components are getting smashed in between the ring and pinion and other moving parts. I mentioned if they have to replace the rear gearing, which is covered under warranty, what would it cost/take to swap the rear gearing out to 4.56 (which they may be able to 'slip-in-there' to be warranty covered), but then to also replace the front gears to 4.56 as well?

My assumption is the rear gear replacement (if they say it's required) should be at a near zero cost as it's warranty work and I can't imagine that much of a difference in cost between 3.73s and 4.56. Of course I'd have to pay for the front.

With that I got to thinking. I run 35" tires and I do haul a ~3500lb camper trailer from time to time. I'm not sure I'd ever go larger than 35" tires, but if I ever went to 37s let's hear your advice on the below...

Knowing that I do haul, with 35" tires would y'all go to 4.56 gears or perhaps 4.88? What if I went to 37" down the road and I wanted to be haul/gear ready? Would the 4.56s be good enough or should I go to 4.88s?
Perhaps for now let me stay in my current world. With 35" tires would you select 4.56 or 4.88 gears?

Also, anyone know what it might roughly cost to have the front gears done?
I know the dealership will probably cost more than a private shop, but I want to maintain the warranty.

Thank You All for any advice.

~justin

 

[buzzarr]

Gearing Advice Please!!!

My non XR 392 w/3.73 gears is at the dealership now. Swung by last night and they said to leave it and they would take a look at it today. My rear electronic locker messed up (I Think). It was making a clucking noise only when turning at slow speeds and when switching on/engaging 4 low it does not mechanically engage. The idiot light came on as well.

Anyways, the service manager said that sometimes when the e-locker fails they have to replace more than just the locker. They may have to replace the gears... and sometimes the entire axle, dependent upon how much damage 'spread around' inside the housing. Makes sense if the locker's components are getting smashed in between the ring and pinion and other moving parts. I mentioned if they have to replace the rear gearing, which is covered under warranty, what would it cost/take to swap the rear gearing out to 4.56 (which they may be able to 'slip-in-there' to be warranty covered), but then to also replace the front gears to 4.56 as well?

My assumption is the rear gear replacement (if they say it's required) should be at a near zero cost as it's warranty work and I can't imagine that much of a difference in cost between 3.73s and 4.56. Of course I'd have to pay for the front.

With that I got to thinking. I run 35" tires and I do haul a ~3500lb camper trailer from time to time. I'm not sure I'd ever go larger than 35" tires, but if I ever went to 37s let's hear your advice on the below...

Knowing that I do haul, with 35" tires would y'all go to 4.56 gears or perhaps 4.88? What if I went to 37" down the road and I wanted to be haul/gear ready? Would the 4.56s be good enough or should I go to 4.88s?
Perhaps for now let me stay in my current world. With 35" tires would you select 4.56 or 4.88 gears?

Also, anyone know what it might roughly cost to have the front gears done?
I know the dealership will probably cost more than a private shop, but I want to maintain the warranty.

Thank You All for any advice.

~justin

I allways match my gears with tire size it's not only because of weight of tire it's also the rotation because the tire is taller you need gears to match the rotation

 

[Smess]

This is the last time I will post this as this topic is getting old.

I have owned a 3.73 and now a Recon both with 37’s

IF YOU ARE GOING TO LEAVE THE 35’S ENJOOY YOUR JEEP AS IT IS

IF YOU ARE GOING TO MOVE TO 37’S AND PULL. A TRAILER THEN GO TO 4.56

4.88 NOT EVEN GOING TO WASTE HALF A HEART BEAT ON THAT THOUGHT ITS SO SILLY.

I OWN A 392 RECON, 4 BANGER 2 DR RECON, A 2 DR 392 (CUSTOM), AND A GLADIATOR ON D60’S WITH 40’S. BEEN BUILDING JEEPS FOR 35 YEARS AND HAVE OWNED HEMI SWAPS SINCE 2009

I DONT KNOW MUCH BUT I KNOW THE ANSWER TO YOUR QUESTION AS I HAVE LIVED IT, ENJOY

 

[Rogue]

On a standard JK/JL with the 3.6, regearing is a must for running 35's

I moved up to 35" Mud Terrain with Beadlock on my 392, which is standard and not the recon. I agree with what @Smess has said, purely because down low it has all the torque to go fast, but I do notice a slight difference in the higher gears, where it downshifts a gear with only a gradual incline of the road. Never had this issue on the original 33's.

That said, the fuel mileage has not changed much.

With my own experience, a regear to 4:56 is well worth it if moving to 37's. The drivability is well worth the upgrade, especially if running heavy, or if towing.

 

[@JC]

Have you reprogrammed the speedo which resets the shift points? I haven't noticed any difference in highway gear usage between the factory 32s and the Falken 35s I swapped on.

 

[justinB]

Update. Here's where I'm at...
I have a 2021 non XR 392 with 35" tires and I tow a 21 foot ~3,500lbs camper trailer monthly. I mention that because the camper has wind drag, it's not the weight so much. The 4.56 gearing will help alleviate powertrain strain.
I'm attempting to be very detailed here because I'm hoping someone may have a suggestion on Mopar 4.56 gearing...

The rear locker was fried. My intent was to have the dealership replace only the locker and I'd be done with it, it'd be fixed and it would have the original 3.73 gears. My initial request, before they opened the differential, was IF they had to replace the differential or gears because of the defective e-locker's collateral damage then to put in 4.56s (I'd pay the difference in the warranty work covering the rear end, if there was any, and of course I'd come out of pocket to have the gearing installed up front). My thought, If they did the work and installed Mopar parts I'd retain warranty coverage and it'd only cost me half as much only paying for the front gears.

Visiting the dealership the next day, the dealership was not able to find 4.56 gears (the ring & pinion set by itself OR a differential assembly w/4.56) in their system for a 2021. They found 4.10s for a 2022 but their system (the parts guy) said since these gears were referenced to a 2022 axle model they may not fit in a 2021 axle housing. As they were uncertain if 2022 4.10s would fit a 2021, they were not willing to chance other gears fitting a 2021 axle as well.

(((Personal thought. I'm not sure I believe there's a difference in the 2021 vs 2022 axles, perhaps their system did not find the gears because Mopar is out of stock on 4.56 gears, I think an unlikely reason though. Or perhaps user error not finding them in the system [all due respect-great guys & gals working there]. Anyways, who knows... Obviously, I don't want the 4.10s, the whole purpose was to see if other gears would actually fit the 2021. And in all fairness the only 392 the service members have worked is mine, there's no hands-on shop experience/knowledge regarding the 392 of any year.)))

Due to a shortage on individual parts e.g. the actual e-locker, and due to a shortage on differentials, they are replacing the entire axle assembly. Gasp! What? Just craziness. And that's with the 3.73 gears, obviously. I could buy both front & rear 4.10 axle assemblies for ~ $9k, but that's not going to happen AND no one could tell me if 2022 axles would even fit. Regardless, I'm not paying ~9k nor do I want 4.10s.

The dealership said IF I was able to do my research and found/bought Mopar 4.56 gears separately they would charge me only for the front & rear install to include updating the PCM and I'd retain warranty.

Like the parts guy, I'm unable to find 4.56 Mopar gears for a 392 which has the WIDE D44 axles. Does anyone know the Mopar part numbers for front and rear 4.56 gearing that'll fit a 2021 non XR 392? My concern, I buy 4.56 gears for a Rubicon but those gears end up not fitting the Rubicon 392's Wide D44 axles.

The link below displays 4.56 gearing for a 392; however, since it's not Mopar I chance losing my powertrain warranty coverage if I have them installed. I'll also include some pics of the defective e-locker and the quote which displays the part number for both the front & rear wide axle housings, the 3.73 gearing for a 2021 392 which is what's currently on my Jeep. This so there's a reference point if anyone knows if/what Mopar 4.56 gears will fit it. That's now my intent, just buy the front & rear Mopar gearing and have the dealership perform the install.
In a worse case scenario I buy non-Mopar gearing and potentially forfeit my remaining warranty. If it saves my transmission 5 years down the road then perhaps it's worth it.

Thanks All for any positive input.

~justin

Dana 4.56 Rubicon Dana 44 210MM/220MM Gear Package; Wrangler JL with Master Install

Regear for those bigger tires to bring back stock performance Price Includes Both Front and Rear Ring and Pinion Sets Front Wrangler JL Rubicon Dana 44 Master Overhaul Kit Rear Wrangler JL Rubicon Dana 44 Master Overhaul Kit For Wrangler JL Rubicon Dana 44 Axles ONLY: 210MM/220MM 8620 Heat...

www.rubitrux.com