Regearing needed for 2.5'' lift and 35" tires on JLU Sport S?

[Mudduck]

Yea i guess my concern is if its such a noticeable difference that regearing is a huge deal just for vehicle longevity. Its a few grand..........so just want to make sure the juice is worth the squeeze is all.

Theres a lot more to needing a regear than just tires. Added weight of bumpers/winch/roof rack/heavier tires and wheels. Will you ever tow a small trailer or camper? theres quite a few reputable shops that will do it under 2 grand. Mine was $1600 change out the door. not much more than the cost of your dream tires.... FWIW

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[word302]

That’s exactly what I wrote. Read again.

No, you said the engine would have more rotations than a properly geared setup. Just want to make sure we keep things clear.

 

[Herson]

No, you said the engine would have more rotations than a properly geared setup. Just want to make sure we keep things clear.

Look, I’ll draw you a map because clearly you don understand. Engine revs are going to be higher in the current axle gear because the transmission will have to be at a lower gear to be at the right torque. Hope you finally understand.

 

[TheBirdie72]

This is why I went rubi takeoff suspension and stopped at 33” tires and new wheels on mine. Any more pounds than 33’s on a 2 door sport and you start running into weight-related issues. I like how my Jeep accelerates and I still see 8th gear regularly. Also, I think 2 doors don’t necessarily need to go to 35’s to get the “look.” Four doors need 35’s imho to get there…

 

[word302]

Look, I’ll draw you a map because clearly you don understand. Engine revs are going to be higher in the current axle gear because the transmission will have to be at a lower gear to be at the right torque. Hope you finally understand.

Look man, I was just trying to clear things up because your post wasn’t clear at all. Have a great day. The idea with lower gears is to get the RPMs HIGHER to get into the power band faster. This is very apparent with the 3.6 as it has terrible off-idle torque.

 

[Djhyper66]

Just re-gear it if you go over 35 inch tires ... nite and day !! Just put it on the todo list !! My sport needed higher gears.. if you have a rubi maybe not as bad .

 

[jeepoch]

@Archer85,

Steve,
I too have struggled with the idea of regearing my lifted 2019 2 door Sport S 3.6L Auto on 35's. However, I decided to run with the stock 3.45 gears for a while just to see how bad it would be.

It turns out to be actually pretty damn good. In fact remarkably good. I'll admit up front however that if I actually drove a similarly configured setup on taller gears, I'd have something to compare and contrast and might change my position. Opinions on this subject are way (way) too subjective and will cover the entire spectrum of 'do this, don't do that' sort of crap. Just look at the banter between some of the last few posts.

Only you can determine what it is you want from your powertrain. For me, torque is important but not as 'over-the-top' essential as everyone seems to claim. First, I have a Sport with open diffs, period. Having wheel slip of any sort spells trouble. My focus is applying just enough torque, but no more, in order to maintain traction through any obstacle or difficult terrain. As long as I can maintain traction with no wheel slip, I can accomplish anything a locking axle can do. Of course, if (and only if) I don't apply too much throttle to slip any wheel. This 3.6L has never (ever) let me down yet.

My conjecture then is that for Sport jockeys, having the biggest, badest gearset on the planet isn't necessarily in your best interest. Something taller than the stock 3.45's may be optimal, but how good is good enough?

I do a heck of a lot of difficult wheeling living here in Colorado. Truthfully though, I'll steer clear of the really extreme crap. My JL, while being a very capable machine, is not a buggy and it is my daily driver after all. I certainly don't baby it, but I don't grind my way through boulder fields just for grins and giggles either.

Regardless, it's the added clearance, disconnected sway bars and most importantly the bigger rubber that works for me. This ZF8 based transmission handles my 35's and 3.45 gears almost as if it was designed to. Really.

Again, how good is good enough? From my personal experience, if someone (such as my long lost 13th great uncle) were ever to bequeath me a set of 4.10 gears, I'd very likely consider installing them. But, after running successfully with my current setup of almost 3 years and 30K of total blissful miles with maybe 15-20% of that off pavement on some pretty awesome mountain wilderness US Forest Service and BLM trails, I have no real motivation to change anything. If I were to do anything more to my Sport to further improve it's capability would be to invest the funds to install locking axles. Not gears.

For those that argue takeoff speed and 80+ mph performance is paramount, I also say hogwash. This thing gives me all the acceleration I need. It really does get up and go. And candidly I bought a Jeep not a Ferrari. Furthermore, I've taught this tranny that I like 8th gear at highway speeds by occasionally manually shifting it there (via AutoStick). It automatically now selects 8th on it's own almost as often as it did with the original stock 31.5" Michelins.

My lifted 3.6L 8 speed JL Sport is exactly (perfectly) calibrated to supply me enough smiles per mile no matter where I navigate this thing. The thought of gearing in order to improve something I'm currently very satisfied with, I've pushed way down on my brain's priority list. For me (and perhaps just me), this setup is certainly good enough. For the true OCD perfectionist, who must always tweak what's not broke, I say do what brings you your own sense of nirvana. I'm already there.

Still if you ship me 4.10 or 4.56 gears, I would be tempted. But clearly only if it's on your dime. Not worth it otherwise.

Jeep on...
Jay

 

[jbcrane]

I'm scheduled to have 4.88's installed on my '21 Unlimited Sport S (3.6L, 6-sp Manual, D30/D44 anti-spin rear) next week. Here's what tipped the scales for me:

Had the Mopar 2" lift installed in late January, as well as bumped up tire size from the stock 31's to 35's (315/70R17's). Upon driving it home that first evening the weight of the larger tires/heavier wheels combined with the lift produced a completely different feeling vehicle. It's different than a stocker Sport S on 31's, no question. But it's AWESOME!.

In the last two months I've grown accustomed to this new normal setup and have been driving and enjoying it tremendously. It now feels completely normal. But I am sensitive to the additional unsprung weight, and 'strain' on systems - namely the problematic clutch.

Because my Wrangler is intended to be a long-term keeper, everything is done with longevity in mind. Here in Colorado 4.88's are going to get me back much closer to that original stock, nimble feeling - especially at altitude. I know what I'll lose: fuel economy on the highway because the engine will be turning higher RPM's around 70-75mph. But that's OK. For longer highway trips I'll take our Subaru Outback. The Jeep is for high-altitude exploring and 4.88's are going to give me back power at altitude. Even before the lift/tires, while cruising at 60mph, I'd step on the accelerator in 5th gear and nothing happened. I really believe the Wrangler is geared too low at 3.45's to begin with, especially here in Colorado. The naturally aspirated engine loses a certain amount of horsepower for each 1,000 of elevation gained (don't remember how much exactly). Here in Colorado, between 7,000' and 12,000 feet above sea level, it's already struggling compared to the same Wrangler at sea level. So that's the real, honest to goodness reason I'm doing it - to get power at altitude - not just back to where it was before lift/tires - but where it should have been originally.

I considered 4.56's but to @Mudduck's post above - don't yet have a clear picture of what additional weight I'll be adding - and don't want to do it twice. So 4.88's seemed reasonable and safe. Having no intention of moving to 37's 5.13's seemed inappropriate for my use.

It's worth noting too that with the stock 3.45's, 5th and 6th gear have become essentially useless. I can get him into 5th gear on the highway - but it throws a ESS error, disabling the Auto Start/Stop and vanishing the gear selector visible on the speedometer. I don't care about not being able to see what gear I'm in. What I do care about is, I believe the addition of that gear indicator on the dash was a product of one of the clutch recall software updates (mine is a '21 and came with all updates and fixes in place). My concern is that in 5th or 6th gear, whatever software update preventing the slipping clutch at highway speeds - is also somehow disabled because the gear indicator is now disabled. Maybe not, IDK. But I'm hoping re-gearing to a 'proper' gear ratio and telling the computer we did so will fix everything.

Yes, it's an expense. Yes, it might seem optional. But to my way of thinking, it will get the Wrangler back where it belongs and everything will hum along a little better, for a little longer. We'll see.

 

[crackrk]

I'm scheduled to have 4.88's installed on my '21 Unlimited Sport S (3.6L, 6-sp Manual, D30/D44 anti-spin rear) next week.
…….
Yes, it's an expense. Yes, it might seem optional. But to my way of thinking, it will get the Wrangler back where it belongs and everything will hum along a little better, for a little longer. We'll see.

I have your same setup (30/44 combo, 6-speed). Trust me, regearing brings your jeep back to life. I’m running 4.56’s with 35’s. It’s like driving a stock jeep again. Other added weight is factory steel rear bumper, LoD mid-width front bumper, winch, MORE aluminum skid plates.

4.88’s might be a little on the high side, but either way anything is better then that garbage 3.45 you’ve got in there now. If I was to do it again I might consider 4.88 only because I’m already starting to think about swapping for a front d44 and 37’s.

 

[jbcrane]

I have your same setup (30/44 combo, 6-speed). Trust me, regearing brings your jeep back to life. I’m running 4.56’s with 35’s. It’s like driving a stock jeep again. Other added weight is factory steel rear bumper, LoD mid-width front bumper, winch, MORE aluminum skid plates.

4.88’s might be a little on the high side, but either way anything is better then that garbage 3.45 you’ve got in there now. If I was to do it again I might consider 4.88 only because I’m already starting to think about swapping for a front d44 and 37’s.

Great to hear. Thanks. I thought about 4.56 but talked to others out here who did it and wished they’d run 4.88’s for the hill climbing alone. Long pulls up I-70 at altitude to the Eisenhower Tunnel, Vail Pass, Cottonwood Pass, McClure Pass, Muddy Gap, Trail Ridge Road, Wolf Creek Pass and countless others that will benefit from a little more oomph… Appreciate the encouragement… Really looking forward to after the break in period when I can really turn him loose.

 

[AlanD]

I have the V6 8 speed open diff in my 2018 JLU. I have hung a tire in the air once or twice while wheeling so I ordered a Dana E locker for the rear differential. I am scheduled to have it installed Wednesday. While I have been reasonably happy with my 35's and a 2 1/2 inch lift, my thoughts have been. Jeep designed to cruise in 8th at a certain RPM not sure if there is a lock in the converter or not. But In the 110 degree heat it runs 5th 6th and sometimes 7th I decided today to let it run as designed at cruising speed so I had Doetsch Tech order a set of 4.88 gears as long as they had the rear opened for the locker install. It will be Saturday before I can pick it up. Then goes back for an diff oil change in 500 miles. In the long run, financial sense, no but Ill be ready for any stranded Broncos i run across.

 

[crackrk]

I thought about 4.56 but talked to others out here who did it and wished they’d run 4.88’s for the hill climbing alone.

Ahhh.. Yeah. That case I’d get 4.88’s. You might lose some top-end speed but it’s a jeep.. not a race car. Best of luck. If you have any more questions feel free to DM me. I’m not on the board often but will respond to DM’s.

Pic of my setup for reference

 

[jbcrane]

Ahhh.. Yeah. That case I’d get 4.88’s. You might lose some top-end speed but it’s a jeep.. not a race car. Best of luck. If you have any more questions feel free to DM me. I’m not on the board often but will respond to DM’s.

Pic of my setup for reference

Good lookin' rig... Love those wheels. It's funny how before lift and tires I'd look at him in the garage and think everything looked about right. Then after lift and tires, realized how at last he looks properly proportioned. I may have some questions about break in I'll send to you. Thanks.

 

[word302]

I'm scheduled to have 4.88's installed on my '21 Unlimited Sport S (3.6L, 6-sp Manual, D30/D44 anti-spin rear) next week. Here's what tipped the scales for me:

Had the Mopar 2" lift installed in late January, as well as bumped up tire size from the stock 31's to 35's (315/70R17's). Upon driving it home that first evening the weight of the larger tires/heavier wheels combined with the lift produced a completely different feeling vehicle. It's different than a stocker Sport S on 31's, no question. But it's AWESOME!.

In the last two months I've grown accustomed to this new normal setup and have been driving and enjoying it tremendously. It now feels completely normal. But I am sensitive to the additional unsprung weight, and 'strain' on systems - namely the problematic clutch.

Because my Wrangler is intended to be a long-term keeper, everything is done with longevity in mind. Here in Colorado 4.88's are going to get me back much closer to that original stock, nimble feeling - especially at altitude. I know what I'll lose: fuel economy on the highway because the engine will be turning higher RPM's around 70-75mph. But that's OK. For longer highway trips I'll take our Subaru Outback. The Jeep is for high-altitude exploring and 4.88's are going to give me back power at altitude. Even before the lift/tires, while cruising at 60mph, I'd step on the accelerator in 5th gear and nothing happened. I really believe the Wrangler is geared too low at 3.45's to begin with, especially here in Colorado. The naturally aspirated engine loses a certain amount of horsepower for each 1,000 of elevation gained (don't remember how much exactly). Here in Colorado, between 7,000' and 12,000 feet above sea level, it's already struggling compared to the same Wrangler at sea level. So that's the real, honest to goodness reason I'm doing it - to get power at altitude - not just back to where it was before lift/tires - but where it should have been originally.

I considered 4.56's but to @Mudduck's post above - don't yet have a clear picture of what additional weight I'll be adding - and don't want to do it twice. So 4.88's seemed reasonable and safe. Having no intention of moving to 37's 5.13's seemed inappropriate for my use.

It's worth noting too that with the stock 3.45's, 5th and 6th gear have become essentially useless. I can get him into 5th gear on the highway - but it throws a ESS error, disabling the Auto Start/Stop and vanishing the gear selector visible on the speedometer. I don't care about not being able to see what gear I'm in. What I do care about is, I believe the addition of that gear indicator on the dash was a product of one of the clutch recall software updates (mine is a '21 and came with all updates and fixes in place). My concern is that in 5th or 6th gear, whatever software update preventing the slipping clutch at highway speeds - is also somehow disabled because the gear indicator is now disabled. Maybe not, IDK. But I'm hoping re-gearing to a 'proper' gear ratio and telling the computer we did so will fix everything.

Yes, it's an expense. Yes, it might seem optional. But to my way of thinking, it will get the Wrangler back where it belongs and everything will hum along a little better, for a little longer. We'll see.

Do you have a programmer? Your likely getting the ESS error because you need to do the 6sp relearn process (check out tazer documentation). 4.88 will be perfect for your setup, just realize that Dana 30 is a major weak point. Also the factory gears are too high, not too low (lower gears are numerically higher).

 

[Stuckinthesand]

Do you have a programmer? Your likely getting the ESS error because you need to do the 6sp relearn process (check out tazer documentation). 4.88 will be perfect for your setup, just realize that Dana 30 is a major weak point. Also the factory gears are too high, not too low (lower gears are numerically higher).

Nothing wrong with the M186 front. These are more robust than the old Dana 30 on previous models. The axle tubes are larger and thicker on the JL. The Cs are beefed up too. You can easily run a 35” tire on this setup with no issues. Heck there is even a few members on this forum that have added a locker to the M186 front with no issues. I run 35”s on my sport s with the M186/M220. I wheel it regularly on stock 3.45 gears and have no issues with the rock crawling I do.

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