"Do I REALLY need to re-gear for 37s?" - Yes. Yes you do.

[Zachanadandy]

Yeah my last quote from the best shop in the area was like $3700 parts and labor.

Sooner or later.....probably after I pay it off early next year i will got with 5.13s and add a front locker. Buy once and cry once

Hated 5.38s in the JL, way too low. Of course I do tend to drive 85mph+ on the freeway so taller gears are better for me.

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[Bonanza]

I installed 4.88s myself. I did a thread on it too. MPG stayed exactly the same. Everytime I floor my gladiator I laugh, because that's how slow it is. I didn't notice it feel faster than 4.10s, but I did notice it in 4hi. 4Hi was unusable before, and now it just feels normal. Slow, and normal.

For instance when I drove my buddy's Rivian-- Aye Aye Aye!! Too much power there, as the massive weight didn't feel controllable. But I'll it each time, I've never had an issue with the reliability of my Jeep, whether it's towing or wheeling. So I'll take it.

 

[Minty JL]

Hated 5.38s in the JL, way too low. Of course I do tend to drive 85mph+ on the freeway so taller gears are better for me.

That's is one of my personal concerns. Many have said they're great.

BUT based on your opinion and experience........considerations to be strongly considered. I have a tendency to drive fast as well while on road trips up to Maine or down to OBX.

In my Tahoe PPV I went from 3.08 to 3.73s and was more then happy. So going from 4.10 to 4.88 would effectively the same gain. I just thought 5.13 is I decided to go to 40s, but If I do that I will be LS swapping anyways and it wouldn't matter with almost 600ftlbs of torque

 

[chr15m]

Some of y'all must have been riving rocket ships before your Gladiator. I had went from a 2016 Yukon Denali with the 6.2L to a stock Rubicon and I felt like the 3.6 had a noticeable increase in pep. I've had several other Jeeps but compared to my TJ from college, this thing feels incredible.

I have the Patagonia X/T 37s on AEV Saltas and I barely noticed a difference from stock. I have no intention to re-gear and on the highway I'm still getting 19-20 MPG with cruise set at 65 (in a 60).

Am I reading that right, you felt like the 6.2 Denali had less go than the 3.6 JT?

We've got a 6.2 Silverado in the family and that thing was faster than my 5.7 Tundra, both of which would hit 60 easily a couple seconds before my JT, like in the 5-6s range. I've seen 6.2s run quarters in the 14s. Pretty much every JT Ive seen, including the diesel is closer to 8s to 60.

 

[Gladiator85]

I did 5.13s with 33s and though it's better vs the mail crawler 4.10s even with wind I still drop to 7th at times. I can say Jeep engineers haven't had it right since 2002 and before with axle or transmission gearing.

You really can't put a low enough axle gear especially on the 42RLE or 850RE. Overdrive is stupidly steep with a motor that doesn't make any usable torque until 2k plus. Kinda wish I did 5.38s especially going 35s down the road. For 37s 5.13s won't be enough gear if you want to stay in 8th longer than a minute or two.

 

[TheSolarWizard]

If running a 3.6 I'd say yes definitely research. My diesel could care less my brother runs 40's on his diesel no research and no complaints. My jk with 35 and 4.88 is barely enough lol

If he drove a diesel with 4.56s and 40s he’d instantly make an appointment to regear. The reason he isnt complaining is he doesn’t realize all the work the 8hp75 is doing to make it pallatable and the torque is hiding the strain. He certainly should be doing fluid and filter changes every 30k until he does

 

[Koolcarguy]

If he drove a diesel with 4.56s and 40s he’d instantly make an appointment to regear.

I don't think so he just drives it around town he has a sport s diesel with 1 tons and 4.88 gears

 

[TheSolarWizard]

I don't think so he just drives it around town he has a sport s diesel with 1 tons and 4.88 gears

I apologize I think I misread what you stated. I thought u said he was driving around on stock gears with his diesel on 40s. 4.56 and 4.88 are both good choices for the diesel on that size, difference being use case. I opted for 4.88s with 42s but I also went way out of my way to keep weight down and i no longer have a hitch

 

[Koolcarguy]

I apologize I think I misread what you stated. I thought u said he was driving around on stock gears with his diesel on 40s. 4.56 and 4.88 are both good choices for the diesel on that size, difference being use case. I opted for 4.88s with 42s but I also went way out of my way to keep weight down

Lol no he is he has 2 diesel Jt's he just opted yo build his sports s instead on the Rubi. I run stock gears with 37 on both my Jt's diesels. 40 are just to big for me these days I still run them on my Lj but it doesn't get much road time anymore

 

[TheSolarWizard]

Lol no he is he has 2 diesel Jt's he just opted yo build his sports s instead on the Rubi. I run stock gears with 37 on both my Jt's diesels. 40 are just to big for me these days I still run them on my Lj but it doesn't get much road time anymore

I chose the sport specifically because of the tcase ratio and knowing id replace everything else.

 

[Jeep-of-Eli]

I went with skinny 37x11.50 on my JTM w/ stock 4.10 gear. It’s still peppy and I still see 8th gear. But I do feel the moment I go w/ 37x12.50, I will have to regear for sure to 4.56 or 4.88.

 

[Wheelin98TJ]

That's is one of my personal concerns. Many have said they're great.

BUT based on your opinion and experience........considerations to be strongly considered. I have a tendency to drive fast as well while on road trips up to Maine or down to OBX.

In my Tahoe PPV I went from 3.08 to 3.73s and was more then happy. So going from 4.10 to 4.88 would effectively the same gain. I just thought 5.13 is I decided to go to 40s, but If I do that I will be LS swapping anyways and it wouldn't matter with almost 600ftlbs of torque

I think he’s talking about a turbo JL.

 

[Zachanadandy]

I did 5.13s with 33s and though it's better vs the mail crawler 4.10s even with wind I still drop to 7th at times. I can say Jeep engineers haven't had it right since 2002 and before with axle or transmission gearing.

You really can't put a low enough axle gear especially on the 42RLE or 850RE. Overdrive is stupidly steep with a motor that doesn't make any usable torque until 2k plus. Kinda wish I did 5.38s especially going 35s down the road. For 37s 5.13s won't be enough gear if you want to stay in 8th longer than a minute or two.

You're trying to get a double overdrive transmission to drive like one without overdrive. Why? That's not the point of 2 overdrives. It's not supposed to hold 8th gear all the time. It's not supposed to cruise around at 40mph in 8th gear. What's the point of an 8 speed auto if you drive around almost exclusively in the top 3 gears? I know for a fact when we had our JLUR with 5.38s and 38s it was in 8th at any speed over 40mph unless you floored it to get it to downshift or you were driving up a mountain. It would cruise through residential neighborhoods at 25-30mph in 5th or 6th. Gearing that low literally turned the 8 speed into a 4 speed in any useable scenario aside from rock crawling. Hell a multi lane wide intersection would have it shifting into 3rd before you were to the other side when the light turned green. The craziest part was it actual got a half second slower 0-60 as it had to shift into 4th gear before it got there. No you aren't burning up the fluid. These things are designed to shift a lot.

 

[RudeJeepin]

I have to wonder if the guys saying not to regear have ever driven one that was regeared. Or if they've ever felt the benefits of a regear in any vehicle for that matter.
My other thought for those that argue 5th on 38s is the same as 8th on 33s...Just tossing out gear vs tires for the argument, not sure if those would make the right ratios vs RPMs...WHY waste gears, you have an 8spd, why wouldn't you want to use all 8 gears???

Sure, around town or maybe even on the HWY it seems fine, but your wasting one of the best parts of the JL/JT if your not using all 8 gears.
That's not to mention offroad. My old CJ5 with a healthy AMC360 had plenty of get up and go on the pavement with 33s and 3.53s. I sure wish it had lower gears every time I got it offroad, especially in the sand. And no, low range isn't always the answer for offroading.

Just my thoughts and opinions. But maybe it's something to think about...

 

[Gladiator85]

I have to wonder if the guys saying not to regear have ever driven one that was regeared. Or if they've ever felt the benefits of a regear in any vehicle for that matter.
My other thought for those that argue 5th on 38s is the same as 8th on 33s...Just tossing out gear vs tires for the argument, not sure if those would make the right ratios vs RPMs...WHY waste gears, you have an 8spd, why wouldn't you want to use all 8 gears???

Sure, around town or maybe even on the HWY it seems fine, but your wasting one of the best parts of the JL/JT if your not using all 8 gears.
That's not to mention offroad. My old CJ5 with a healthy AMC360 had plenty of get up and go on the pavement with 33s and 3.53s. I sure wish it had lower gears every time I got it offroad, especially in the sand. And no, low range isn't always the answer for offroading.

Just my thoughts and opinions. But maybe it's something to think about...

My point exactly . Why have an 8sp if the conditions have to be just right to use all gears? Also why does Jeep offer 4.56 and 4.88 options even on 33s? If it was so bad to regear why would they have Dana install those gears?

While it might shift out of 8th at times if it can't hold 8th or even 7th for longer than a minute or two on the highway that's a sign you don't have enough power to maintain overdrive. Also it can't be good at high speeds for the converter to constantly come out of lock up and slip during that time. That's like riding down the road with your foot resting on the clutch of a manual. Way more heat and friction created.

In fact at 100k I lost a torque converter clutch on my old 05 LJ with 3.73s and 32s. It constantly came out of 4th unless flat ground no wind or hills.

On my JT I have 12k on it. Before I regeared probably only stayed in 8th maybe half those miles total. That's alot of shifting way more than normal stop and go. That's wear and tear no matter how much you think it likes to shift.

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