Newbie - Totally lost on what to do with gearing

[boston3111]

Bought a 2021 JLU Willys a few months back. Fast forward and the Willys now sits on a 2.5 JSPEC JKS lift with 35x12.50 Nitro Ridge Grapplers. Running spidertraxx 1.75 spacers with stock 17s.

Drove it around for the past few weeks with the stock geasr which I believe is 3.73 or smaller (not sure to be 100%).

I am thinking I want to go with with a bigger tire, up to 37's. Which gearing should I go with? I do plan on swapping out the front Axle for either a ProRock 44 or a UD 44. Make sense to just get one of those and I can add a locker and gears! Just not sure on what gears to get? I run a lot of highway and this will be a road tripper for the Wife and I.

Any tips ya'll can share would be great! Try to post a few pics of it here soon.

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[Fouts]

I have the manual transmission am thinking of going to 5:13s. Did 4:88 on my JK and did really well with auto and 37s. Motor may make a difference. I have the 3.6

 

[jlewissystem]

From what I see: (we run 37s on both an auto 2.0 and a manual 3.6 rubicons)

For the 3.6:
Auto-4.88s
Manual-5.13s

For the 2.0:
No re-gear needed to turn up to 37s, with personal experience.

Can’t say for the 3.0

 

[UNC Rubicon]

Paging @chevymitchell

 

[Qjoh5510]

If going to 37s and want a somewhat stock like drive then do 4.88. That’s what I have and I’m happy with it.

 

[conFUcius]

For the 3.6 with auto, 4.88 puts it to stock (similar to the OEM 4.10 gear ratio of a Rubi). Some of us (myself included) have gone to 5.13s to accommodate the heavier weight of aftermarket mods too. Don’t think you can go wrong with either.

 

[plex]

One thing to keep in mind as you going (numerically) up the gear, the pinion size get smaller and smaller. If you over gear, you Sports axle won't appreciate the extra load with small pinion.

 

[AnnDee4444]

One thing to keep in mind as you going (numerically) up the gear, the pinion size get smaller and smaller. If you over gear, you Sports axle won't appreciate the extra load with small pinion.

While that's true for this scenario, it isn't always 100% accurate.

 

[Jeep’n Jay]

If you are going to 37's, do 5.13's and don't overthink it. I went back and forth and ordered 4.88's. The day I was dropping it off at the shop and talking with the installer, he convinced me to hold off and go 5.13's. Fast forward, had 5.13's installed and SO glad I did instead of the 4.88's. Gas mileage is up. I can hold 8th gear even better than when it was stock. I can still cruise at 75mph no issues at all.

 

[boston3111]

Thank you for all the ideas fellas. I somehow got lucky and my local shop had a set of 2021 rubicon axles off of a build and I picked them up for $4k for the set. Going to go with 5:13s and am now on the hunt for 37s.

 

[boston3111]

If you are going to 37's, do 5.13's and don't overthink it. I went back and forth and ordered 4.88's. The day I was dropping it off at the shop and talking with the installer, he convinced me to hold off and go 5.13's. Fast forward, had 5.13's installed and SO glad I did instead of the 4.88's. Gas mileage is up. I can hold 8th gear even better than when it was stock. I can still cruise at 75mph no issues at all.

My local shop said the same thing. I do a lot of highway driving so excited to see how it drives on the highway.

 

[rcadden]

From what I see: (we run 37s on both an auto 2.0 and a manual 3.6 rubicons)

For the 2.0:
No re-gear needed to turn up to 37s, with personal experience.

Really? Part of the reason I didn't want to do the MOPAR lift + 35s on my Sahara Altitude 2.0L is because my understanding is that 35's bring the need for regear (and upgraded spare tire carrier).

If I could go to 35's without regearing without issue, that would definitely shift them up in the priority range for my mods list.

 

[Some Random Guy]

Auto and lots of highway driving, so I would actually consider 4.56. If you had rubicon gears and a 2.0 I’d consider staying put at 4.10, but since you’re regearing anyway I’d target 4.56 to help out on road trips. I was crawling with 39’s on 4.10 and it was surprisingly fine last week.

 

[jlewissystem]

Really? Part of the reason I didn't want to do the MOPAR lift + 35s on my Sahara Altitude 2.0L is because my understanding is that 35's bring the need for regear (and upgraded spare tire carrier).

If I could go to 35's without regearing without issue, that would definitely shift them up in the priority range for my mods list.

Well sir - i will tell you that: my wife has been driving her 2.0 on 37's for 2 years now and we've done 12 trail badges and more with our jeeps. She doesnt tow, but she has not re-geared. When i drive it, it seems to have no issues. If it had 35's, it would be even faster! lol

Now, we have Rubi's so they'e 4.10s. The Sahara's have 3.45s (i believe). I dont have any experience with that ratio or the difference between 3.45s & 4.10s. Someone else will have to comment on that.

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