Regear Debate

[Bigdave18629]

Hello, I understand that I could be opening Pandora's box with this question. I recall having read through a couple of threads on the subject, but for the life of me, I can't find them.

I have a 2020 JLU Willis, running 35's (effectively 34). Auto trans, 3.43 factory gears. I am thinking pretty hard of going to 4.56. I am not going to be doing any real crawling, mainly fire and forest service roads in Nor-Cal. Live pretty much as sea level, trails around 5,000 ft. The jeep is a weekend toy, not a daily. Have to drive a couple of hours to get to some decent trails.

I have read that other than the top end gearing you won't see much benefit from regearing with the auto. On the flip side, I have read that you notice a night and day difference, even at the low end after the regear.

I won't be going with bigger tires. So is the $2,700 better spent on something else, or is gearing the best bang for the buck?

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[toothirtyj]

Best bang for the buck. You'll love it and wonder why you didn't do it sooner.

 

[Bleda2002]

Hello, I understand that I could be opening Pandora's box with this question. I recall having read through a couple of threads on the subject, but for the life of me, I can't find them.

I have a 2020 JLU Willis, running 35's (effectively 34). Auto trans, 3.43 factory gears. I am thinking pretty hard of going to 4.56. I am not going to be doing any real crawling, mainly fire and forest service roads in Nor-Cal. Live pretty much as sea level, trails around 5,000 ft. The jeep is a weekend toy, not a daily. Have to drive a couple of hours to get to some decent trails.

I have read that other than the top end gearing you won't see much benefit from regearing with the auto. On the flip side, I have read that you notice a night and day difference, even at the low end after the regear.

I won't be going with bigger tires. So is the $2,700 better spent on something else, or is gearing the best bang for the buck?

Our JLU is a 4xe so it didnt need a regear, but the best 2K I ever spent on the gladiator was regearing. Went to 5.13's from 4.10s and it was noticeable at all speeds, but especially that all important (for DD) 0-40 and also passing power above 70. Its just made it so much more fun to drive and useable both on an off road that I'm a full convert to the church of the regear.

I firmly believe that the only people who'll say its not worth it either didnt go deep enough (4.10 to 4.56 for example), have a diesel/4xe/392, or havent actually driven a regeared Jeep.

 

[Jeep’n Jay]

Overall my favorite upgrade I’ve done. You can get by with factory gears but it is night and day difference when’s it is geared correctly.

 

[grimmjeeper]

Some people will tell you that you don't need to regear. Some will even try to baffle you with a bunch of crap, including charts they made. But they're full of it.

Bottom line is that the automatic transmission covers up a lot of the inadequacy of an under geared Jeep. For 35" tires and coming from 3.45 gears I wouldn't go less than 4.56. And given your use case I'd probably stop there.

A rubicon with 4.10 stock would be adequate and I wouldn't change them.

For more aggressive rock crawling I'd probably go further with 4.88 but that's not what you are doing.

I would also suggest adding a limited slip differential like a TrueTrac if you can in the rear axle. You will save paying install cost twice if you do the two together.

 

[Bigdave18629]

Some people will tell you that you don't need to regear. Some will even try to baffle you with a bunch of crap, including charts they made. But they're full of it.

Bottom line is that the automatic transmission covers up a lot of the inadequacy of an under geared Jeep. For 35" tires and coming from 3.45 gears I wouldn't go less than 4.56. And given your use case I'd probably stop there.

A rubicon with 4.10 stock would be adequate and I wouldn't change them.

For more aggressive rock crawling I'd probably go further with 4.88 but that's not what you are doing.

I would also suggest adding a limited slip differential like a TrueTrac if you can in the rear axle. You will save paying install cost twice if you do the two together.

Thanks, I have a factory LSD that I didn't mention. So far doesn't seem to be much of a debate.

 

[grimmjeeper]

Thanks, I have a factory LSD that I didn't mention. So far doesn't seem to be much of a debate.

Given the low quality of the factory limited slip, I'd still consider an upgrade to a TrueTrac.

The factory limited slip is a clutch style that wears out and doesn't limit slip. It also can have problems with reliability in other ways. More than a few chuck bits of spider gear.

The TrueTrac is a helical gear design that doesn't wear out and it is much more reliable in the long run.

 

[word302]

Some people will tell you that you don't need to regear. Some will even try to baffle you with a bunch of crap, including charts they made. But they're full of it.

Bottom line is that the automatic transmission covers up a lot of the inadequacy of an under geared Jeep. For 35" tires and coming from 3.45 gears I wouldn't go less than 4.56. And given your use case I'd probably stop there.

A rubicon with 4.10 stock would be adequate and I wouldn't change them.

For more aggressive rock crawling I'd probably go further with 4.88 but that's not what you are doing.

I would also suggest adding a limited slip differential like a TrueTrac if you can in the rear axle. You will save paying install cost twice if you do the two together.

I wonder who this "some people" is you are referring to

 

[AdamG]

Just went to 4.56 on my 2dr 3.6L 6spd, still on 33s but going to 35s. 2500rpm is a about 73mph, drives so much better.

 

[Gunfighter]

Curious to see if there would be an actual 0-60 improvement going from 3:73 (3.6L / HA) to 4:56. This is a considering move. Thinking that it might knock off .5 secs, but the torque "feel" would be better and more usable in the dunes...thoughts? experience?

 

[Tncdrew]

Some people will tell you that you don't need to regear. Some will even try to baffle you with a bunch of crap, including charts they made. But they're full of it.

Bottom line is that the automatic transmission covers up a lot of the inadequacy of an under geared Jeep. For 35" tires and coming from 3.45 gears I wouldn't go less than 4.56. And given your use case I'd probably stop there.

A rubicon with 4.10 stock would be adequate and I wouldn't change them.

For more aggressive rock crawling I'd probably go further with 4.88 but that's not what you are doing.

I would also suggest adding a limited slip differential like a TrueTrac if you can in the rear axle. You will save paying install cost twice if you do the two together.

This is solid advice! Great points made by a trusted member.
I made the same changes (3.6L/8-spd), went to 4.56 gearing. I have 34" tires. I also upgraded the OEM rear LSD to a Nitro Helix (also a Torsen type) LSD.
The gearing change made a world of difference in the Jeeps driveability.
By changing to larger than OEM tires, you are absolutely deteriorating the original performance level of the vehicle. That's the plain truth. A re-gear obviously restores that performance.
I believe you'll be very pleased with the results if you regear.
Happy Jeeping! ?

 

[AdamG]

Curious to see if there would be an actual 0-60 improvement going from 3:73 (3.6L / HA) to 4:56. This is a considering move. Thinking that it might knock off .5 secs, but the torque "feel" would be better and more usable in the dunes...thoughts? experience?

Can’t say about 0-60 but with a manual, the in-gear acceleration is night and day different. Before, if I were in 3rd at around 25mph and hit the gas, there was a lazy attempt to go faster. Now, it just goes. The gearing feels much better, more controlled, and first is still not too deep on 33s. If I were doing more crawling maybe 4.88 would be better, but as a daily in Michigan that goes on a couple offroad trips per year, I’m very happy with what I got.

 

[c20040215]

Some people will tell you that you don't need to regear. Some will even try to baffle you with a bunch of crap, including charts they made. But they're full of it.

Those charts suck I dont know why he is so proud of them. Another forum member @AnnDee4444 made one that is very helpful to give an idea what ratio you should choose.

 

[aldo98229]

My Sahara runs on 35s; had 4.88 gears put on a year ago. Best decision I ever made.

Just wish Eaton offered a TrueTrac for our Jeeps back then. I’d have had it swapped then, too.

 

[Bigdave18629]

This is solid advice! Great points made by a trusted member.
I made the same changes (3.6L/8-spd), went to 4.56 gearing. I have 34" tires. I also upgraded the OEM rear LSD to a Nitro Helix (also a Torsen type) LSD.
The gearing change made a world of difference in the Jeeps driveability.
By changing to larger than OEM tires, you are absolutely deteriorating the original performance level of the vehicle. That's the plain truth. A re-gear obviously restores that performance.
I believe you'll be very pleased with the results if you regear.
Happy Jeeping! ?

Thanks, like hearing it from someone with a near identical set up....torque =

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