Should I Regear?

[crystalbackJL]

Personal opinion and maybe somewhat unpopular but you should re-gear to compensate for the tires you're planning on running for the long term. Doesn't matter if it's a Rubicon and its 4.10s going to 35s or a Sport and its 3.45s going to the same. It's the single biggest quality of life improvement you can make for mileage and driveability. It will make every time you take your Jeep out more enjoyable. You may have to wait a bit longer for those bumpers, winches and lights you'll never use but...

I went with 4.56s on my 2dr Rubicon and 35s.

My opinion ( which doesn't mean anything)
33's/4.10's
35's/4.56's
37's/4.88's
Etc.......

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[Cycle11111]

I'll be using the jeep mostly for daily driving as of now. if anything later on, easier trails no rock crawling. I'm seeing a lot of information saying that 4.56 is the way to go. I have the 8 speed automatic and it doesn't go into 8th gear anymore on the highway. Can you tell me what differences I'll notice with the 4.56 as compared to the 3.45 I have now?
Admittedly I'm new to all these jeep mods with regard to gears and axles. Any information helps.

I have a sport that I upgraded axles and re-gear to 4.88s on true 35s. I now get a 2mpg improvement on the highway as the engine stays in the power band and wheeling is much more comfortable. Also on the highway I see 7th and 9th gear all the time but with my old 285s and the 3.45 gears 8th was literally a myth except downhill and 7th was always downshifting to 6th gear

 

[Ian4351]

I have a sport that I upgraded axles and re-gear to 4.88s on true 35s. I now get a 2mpg improvement on the highway as the engine stays in the power band and wheeling is much more comfortable. Also on the highway I see 7th and 9th gear all the time but with my old 285s and the 3.45 gears 8th was literally a myth except downhill and 7th was always downshifting to 6th gear

Which engine do you have?

 

[SouthernJL]

I did not see the engine posted anywhere (I may have missed it), but if a 3.6L and a ZF8, this is what I would do:

33" = 4.56
35" = 4.88
37" = 5.13
38+ = 5.38

I have been through the range in my 2019:

33" + 4.10
35" + 4.88
37" + 4.88
37" + 5.13

So I believe I am in a good position to give you some advice--4.88 is going to be the sweet spot and it will be peppy and I think you will enjoy it much more than 4.56 gears.

What is your altitude?

 

[word302]

I don't think this is true. When I had a JKU (with 3.10s I think?)and moved to 35s, I absolutely needed to regear, and I did, to 4.56.

I already knew I wanted to go to 37s when I got my JLUR and fully planned to regear based on my JKU experience. I was told by another really experienced Jeeper that re-gearing is not needed or at least not urgent due to the 8 speed trans in the JL. After getting my 37s, I agree with him. But it also depends on your location and use case.

I'm in Atlanta (near sea level), have the Rubi (4.10s), I have the K02 C load 37s (super light) and as of now my Jeep is a pavement princess. Did the Jeep take a hit to performance compared to stock? Yes. Is it worth spending 2k for a re-gear for marginal improvement? Not for my use case. If my use case changes then maybe I'd start considering a re-gear. But compared to my JKU, my JLUR still has plenty of get up and go.


What is your altitude?

Which is pretty much what I’ve been saying. The OP (and the person that comment was directed at) has 3.45 gears though, so kind of a different conversation. I lived with 4.10s and 37s for almost 2 years. I have the manual transmission so a little more painful than your case, but gearing to 5.13 has been the best mod I’ve done. I did the work myself so it only cost about half what you’re talking. I agree there are a lot of factors that go into a gearing choice. I live in the PNW where almost nothing is flat.

 

[76_iron]

I would find some take off Rubicon axles and see if you can live with the 4.10 gears for awhile before I put any money into upgrading sport axles.

 

[SouthernJL]

It is 7K now, but I had 4.10 + 33, 4.88 + 35, and 4.88 + 37 at sea level. I moved to 5.13 after moving to Colorado because the 4.88's and 37's were not cutting it.

On a 3.6L/ZF8, 4.10s and anything over 33's is sub-par even at sea level. Take 4.10s and 33's into any altitude and it will be painfully obvious the gearing is not correct, much less 35s or 37s,

While you may find it not "worth spending 2k for a re-gear", it is in no way a marginal improvement to re-gear from 4.10 to 4.88/5.13 for 37" tires and speaks to the statement that @word302 said--if you have not driven a properly geared vehicle, then you do not know what you are missing, ergo, you don't know what you don't know.

The same statement applies to those who say the ZF8 will compensate. No, it won't. It may mask the issue, but it cannot compensate for the loss of the overall gear ratio. This is why you hear so many say they lose 8th and sometimes 7th gear on the highway...

Because I had a JKU that I changed from stock to 35s, I have first hand knowledge on the power loss incurred in that swap. I also know how much performance rebounded when I re-geared to 4.56. So I totally get what you're saying.

The power loss experienced when going to 37s on my 4.10s was not as extreme as the power loss on the JKU. It was absolutely a 100% no-brainer with the JKU. On the JLUR I'm simply saying it's less of a must do.

I'm not stating fact that there is no power loss. Of course there is. I'm saying the loss incurred is more in realm of up to the driver discretion depending on their use case . I generally disagree with someone using their use case as the bible for others to follow for their situation This is why I gave an opposing opinion.

 

[Ian4351]

What is your altitude?

Sealevel now but possibly moving to Colorado lol. What does altitude affect?

 

[word302]

Sealevel now but possibly moving to Colorado lol. What does altitude affect?

Nothing for you once your turbo kicks in. You will have less power at low end/no boost situations. So likely affect gas mileage even more as you’ll be using that turbo more often. I’d say for you with a 2-door turbo that 4.56 will still be fine unless you think you’ll ever move up in tire size.

 

[Remorseless]

OP's got the 2.0T. Altitude will have less of an effect on them.

 

[Cycle11111]

Which engine do you have?

Sorry good point - 3.6 (none e-torque)

 

[word302]

OP's got the 2.0T. Altitude will have less of an effect on them.

Yeah other then the turbo kicking in a lot more.

 

[entropy]

I used to be on the fence with re-gearing. As I've gained some experience, I changed my mind.

For off-roading situations you will have more control of the vehicle and be able to crawl much better. I am on heavy 33s and 3.45s and I can already feel the handicap as crawling with the 3.45s is a bit of a challenge, if you can even call it crawling. I can't imagine with 35s, Id be flooring the throttle and spinning tires. Technically you'd able to get more torque at the wheels at lower speeds. It is simple, the high speed from the shaft is converted to a much lower speed at the differential than it was before. Like riding a mountain bike on the lowest gear.

For the pavement it is a bit different. If I was just driving my Jeep on the road and never off-road I would save my money and keep the stock gears, assuming auto transmission. That's not to say you wont benefit from it though. You will get better acceleration when passing other cars, merging into the freeway, and rolling from a stop. Essentially you are trading top speed with acceleration, and who needs top speed on a Jeep?.

So yeah. Regearing should improve your jeep's performance on the pavement and offroad. Do it for the performance gain and not the mileage. If you do it for better mileage you'll be disappointed.

In the end it is for you to decide if it is worth the $$$. For some people it is, for others it isn't. Your Jeep will perform decently with stock gears on pavement. For some, that might be good enough.

 

[word302]

I used to be on the fence with re-gearing. As I've gained some experience, I changed my mind.

For off-roading situations you will have more control of the vehicle and be able to crawl much better. I am on heavy 33s and 3.45s and I can already feel the handicap as crawling with the 3.45s is a bit of a challenge, if you can even call it crawling. I can't imagine with 35s, Id be flooring the throttle and spinning tires. Technically you'd able to get more torque at the wheels at lower speeds. It is simple, the high speed from the shaft is converted to a much lower speed at the differential than it was before. Like riding a mountain bike on the lowest gear.

For the pavement it is a bit different. If I was just driving my Jeep on the road and never off-road I would save my money and keep the stock gears, assuming auto transmission. That's not to say you wont benefit from it though. You will get better acceleration when passing other cars, merging into the freeway, and rolling from a stop. Essentially you are trading top speed with acceleration, and who needs top speed on a Jeep?.

So yeah. Regearing should improve your jeep's performance on the pavement and offroad. Do it for the performance gain and not the mileage. If you do it for better mileage you'll be disappointed.

In the end it is for you to decide if it is worth the $$$. For some people it is, for others it isn't. Your Jeep will perform decently with stock gears on pavement. For some, that might be good enough.

I would argue that the benefits on road far outweigh the off-road benefits. That’s coming from someone who built his Jeep as a toy more for off-road than on.

 

[SouthernJL]

I used to be on the fence with re-gearing. As I've gained some experience, I changed my mind.

For off-roading situations you will have more control of the vehicle and be able to crawl much better. I am on heavy 33s and 3.45s and I can already feel the handicap as crawling with the 3.45s is a bit of a challenge, if you can even call it crawling. I can't imagine with 35s, Id be flooring the throttle and spinning tires. Technically you'd able to get more torque at the wheels at lower speeds. It is simple, the high speed from the shaft is converted to a much lower speed at the differential than it was before. Like riding a mountain bike on the lowest gear.

For the pavement it is a bit different. If I was just driving my Jeep on the road and never off-road I would save my money and keep the stock gears, assuming auto transmission. That's not to say you wont benefit from it though. You will get better acceleration when passing other cars, merging into the freeway, and rolling from a stop. Essentially you are trading top speed with acceleration, and who needs top speed on a Jeep?.

So yeah. Regearing should improve your jeep's performance on the pavement and offroad. Do it for the performance gain and not the mileage. If you do it for better mileage you'll be disappointed.

In the end it is for you to decide if it is worth the $$$. For some people it is, for others it isn't. Your Jeep will perform decently with stock gears on pavement. For some, that might be good enough.

This is entirely the point I was trying to make. I love my Jeep but I certainly didn't buy it for its main intended purpose (off-roading). I bought it for its uniqueness. For the time being, it remains on the pavement.

While this site is definitely comprised of oodles of hardcore, offroading enthusiasts, it also has tons of members like me, who bought a Wrangler because it's just a cool vehicle. I wanted to give a perspective from that view point.

Also, @CarbonSteel mentioned changing tires 2x and gears 3x so obviously money is of no object to him. This is far from the case for most folks. For some people, the expense of 1 gear swap would be tough to swallow. My goal was to just let the OP see a perspective that differs from a hardcore enthusiast, which by the way, most Jeep owners are not.

That way he can weigh the pros and cons from both opinion camps. Ultimately, he won't 'break' his Jeep if he keeps his factory gears. Just felt he needs to know that as he makes his decision.

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