[gear ratio redo]

[JL_o|||||||o]

i have a ‘24 Wrangler, manual trans, 3.6L v6
Ques: if i get a 3” lift and install 37 tires,
do i have to redo all the gears to calibrate
from factory 245/75/17?

a mechanic at a dealership mentioned
it and kinda bummed me out; I hope
this isnt entirely true.

Thank you for any feedback!!

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[gek]

To calibrate what, the speedometer? For that you can just get Jscan or a tazer and tell it what size tires you have, or have your dealership update it.

From a drivability standpoint, you are likely going to want to regear, unless you prefer to never use 6th, and possibly 5th, gear. I assume you have factory 3.45s in a non rubicon based on your tire size. I regeared to 4.56s after I put on 35s and it was the second best mod I did to my Jeep other than replacing the terrible factory clutch with an ACT.

 

[azwjowner]

Yes, you will need to regear assuming your current gear ratio is 3.45. Not because of calibrating for the tires—that’s a separate matter. But the bigger tires require different gearing to match. Most here would suggest 4.88 for 37 inch tires.

 

[grimmjeeper]

It's a good idea to do it. Especially with a manual transmission. Even more if you don't have the Rubicon with 4.10 gears.

You can try driving ot without updating the gears but you'll find out pretty quick that getting started off the line will be more of a challenge and you'll lose the ability to maintain speed in 6th or possibly even 5th.

 

[AlgUSF]

You’ll want to lose the Trak-Lok carrier while the diff is apart.

 

[Chetjet]

You don't have to do a gear change but IMO it is worth it even if you don't plan on doing any serious off roading. I have a 2018 sport with a manual, 3.6, 35" tires, 3.5" lift and 4.88 gearing with helical LSDs. My jeep is my daily driver and I drove it for a few months with the 35" tires before changing the gearing. The drivability got phenomenally better after the gearing change and my MPG got a tiny bit better to.

 

[skiddymo]

i have a ‘24 Wrangler, manual trans, 3.6L v6
Ques: if i get a 3” lift and install 37 tires,
do i have to redo all the gears to calibrate
from factory 245/75/17?

a mechanic at a dealership mentioned
it and kinda bummed me out; I hope
this isnt entirely true.

Thank you for any feedback!!

I have the same setup. I put a lift and tires on and now I really need new gears. Been driving it since May and 5th and 6th are obsolete. Probably going to go with 4.56 and 35’s. Hopefully not in the to distant future.

 

[BuyHold]

Regearing is expensive. As several have said in this thread and I myself can vouch for, can be one of the best mods you can do, especially if you have a 6sp (as I myself do).

I have 35s and 5.13s and it is tremendously better. In fact, I love it. For some time I had the 4.10s with 35s and it was edge of tolerable IMO. I seriously think I would have strongly disliked 4.10s on a 37 but I can't speak from experience that you would. Will say that unless you are going 80mph, you likely won't be using 6th gear.

As gek said, you can simply "recalibrate" the computer with Tazer or Jscan or dealer visit but that would just fix the speedo reading, the driveline experience will remain unchanged unless you regear.

 

[azwjowner]

I have the same setup. I put a lift and tires on and now I really need new gears. Been driving it since May and 5th and 6th are obsolete. Probably going to go with 4.56 and 35’s. Hopefully not in the to distant future.

Go for 4.88. I have 4.56 on 32" tires and it's great.

 

[JT1]

It's a good idea to do it. Especially with a manual transmission. Even more if you don't have the Rubicon with 4.10 gears.

You can try driving ot without updating the gears but you'll find out pretty quick that getting started off the line will be more of a challenge and you'll lose the ability to maintain speed in 6th or possibly even 5th.

It won't pull a rise on the highway in 5th at 85.. It'll be a 4 speed.

 

[skiddymo]

Go for 4.88. I have 4.56 on 32" tires and it's great.

I might just do that. Can I ask what the cost was? I am debating on doing the work myself. It is one of those things I just haven’t done before. But I am mechanically inclined so that should help. Started watching some videos and we will see.

 

[azwjowner]

I might just do that. Can I ask what the cost was? I am debating on doing the work myself. It is one of those things I just haven’t done before. But I am mechanically inclined so that should help. Started watching some videos and we will see.

I did it myself. I basically followed just one video, as this guy is very good and easy to follow. I had my ipad out in the garage and just would replay step by step and went through it. That was my entire procedure:

And for the front Dana 30:

Chevymitchell has a write up on this forum but he took apart things like the parking brakes that were unnecessary and I found it much easier to follow the video than his written steps. (He is a very very helpful guy though and I ended up contacting him when I had a question halfway through).

 

[skiddymo]

I did it myself. I basically followed just one video, as this guy is very good and easy to follow. I had my ipad out in the garage and just would replay step by step and went through it. That was my entire procedure:

And for the front Dana 30:

Chevymitchell has a write up on this forum but he took apart things like the parking brakes that were unnecessary and I found it much easier to follow the video than his written steps. (He is a very very helpful guy though and I ended up contacting him when I had a question halfway through).

Thanks! I think this would be a good winter project for me. Depending on the cost of the gears and what tools I will need that I don’t have.

 

[Oletimer]

Do the 5.13s. You won't regret it.

 

[AlgUSF]

Thanks! I think this would be a good winter project for me. Depending on the cost of the gears and what tools I will need that I don’t have.

I did mine, there are some tools that I didn't have that I needed.
1: Bearing Puller
2: Dial Indicator
3: Beam-syle inch-lb tq wrench
4: Brass Drift
5: Bearing and Seal driver kit
6: Big-a$$ Tq Wrench to get the ring bolts to 140 lbf-ft

I ended up finding a local machine shop to press my carrier and pinion bearings, one time he charged me $30 and the next it was $20. For me it was better than owning a press in my limited garage space.

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