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

[drew0622]

I found this video very interesting, pretty straight forward on this very subject. ba34609_v1_mb_vsquiz-quiz-yt-adapt-44444_v2_visa_vvdrpi.mp4 (youtube.com)

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[PeterPriesthood]

JTR on 38’s, no re-gear. I’m actually shocked at how well it drives. It’s a rocket ship compared to my land cruisers. My supercharged tundra on 35’s will probably get a re-gear before the jeep does, the transmission is that good. I’m in Utah at 5,000’. For me the change from stock is noticeable but it’s surprisingly livable for me, and I am pretty sensitive to that stuff (ergo, supercharger on the Toyota, re-geared past land cruisers and other trucks).

Trail Recon was at 5:13’s and 38’s, and he switched down to 37’s and 4:88’s. Thought the balance of off-road, city, and hwy driving was better at that combo. Probably what I would do after these wear out (also wanting to get a full size spare under the bed…)

 

[Zachanadandy]

I think most of us here know what an auto transmission is supposed to do.

Yes there are 3.45 geared Jeeps with 32” tires, but there are also 4.10 geared Jeeps with 32” tires and even 4.88 with 32s.

Good thing there are options because there are some different opinions and different needs and wants.

The factory gearing options only contribute to the confusing, but the "need to regear camp" uses terms like proper and stock gearing, entirely ignoring the existence of all these taller geared Jeeps from the factory. The fact is a gladiator or JL with 4.10s and 37s drives, shifts, and runs similar rpms under similar loads to the vast majority of Jeeps on the road as most are stock and not rubicons. I'm not saying 4.10s are the perfect ratio for 37s, but to argue they are wrong, out of whack with the most popular gearing sold by Jeep, etc it's just flat untrue. If I was gearing for 37s I'd go 4.56s, but i drive fast. I could maybe see 4.88s for my use but hated 5.38s and 38s on the freeway. I actually liked 4.10s and 37s, both in that JL that we eventually regeared and in my JT mojave better everywhere. The 100-1 crawl ratio even with 38s made 1st gear in 4LO nearly useless.

 

[Greg_L]

New Gladiator owner. 2023 Willys Sport. 3.6L. 3.73 gears, Dana 44 axles.

I live in a very flat area near sea level and besides going to the beach my Jeep will never see offroad stuff like boulders and mountains and cliffs and volcanos. It's a city rig mallcrawler. This thread convinced me to try 37s and no re-gear.

I will be doing a mild 2-2.5" lift and already have a fender delete.

 

[JT1]

New Gladiator owner. 2023 Willys Sport. 3.6L. 3.73 gears, Dana 44 axles.

I live in a very flat area near sea level and besides going to the beach my Jeep will never see offroad stuff like boulders and mountains and cliffs and volcanos. It's a city rig mallcrawler. This thread convinced me to try 37s and no re-gear.

I will be doing a mild 2-2.5" lift and already have a fender delete.

The automatic is much more gear tolerant than the 6spd. Start with your cruising speed and work backwards. If you spend a bunch of time on the highway at 80+ you might not mind it.

 

[Minty JL]

 

[Greg_L]

The automatic is much more gear tolerant than the 6spd. Start with your cruising speed and work backwards. If you spend a bunch of time on the highway at 80+ you might not mind it.

I do a lot of freeway/city driving. Zero hills....unless a freeway overpass counts as a hill. Like I said, the only offroad I see is driving through loose sand on a beach. I might drive across a median to avoid traffic. LOL. I'm a musician that hauls musical gear in his Gladiator. I'm interested in the aesthetics.

 

[Greg_L]

Ok so I'm going about a week now on 37s with 3.73 gears.

Did a speedo recalibration with an ECRI unit. I'm honestly not seeing or feeling any problem with the gearing. I see 8th all the time on the freeway and my gas mileage has actually improved a little. Granted I live in a very flat region and the only hills I see are highway overpasses, but still, feels good to me.

Not to buck any trends or advice, just my observations.

 

[Escape.idiocracy]

Yo, brother, Where are you located? How are the patagonia Xt's in the 37"? Had it in snow/ mud/ offroad? Lert me know. Very interested in your take on these tires. Can't find many reviews (besides the bad ones)

I have had our 37 XT’s on for 20k miles now and they are hardly worn….4 tire rotations every 5k because I’m too lazy to cycle in the spare. They are great off road, snow/mud they do really well. Rocks they aren’t the MT’s but they do well.

They are rated for 40k miles if I remember right. At the rate of wear I bet we will get 50k from them…. And I say this as 50k and mild off road capable. Probably 60k of just street miles. (Unless the back half wear super fast….)

I was kinda hoping they would be done in 30-40k so I could jump to 40’s.. but it’s fine I suppose. It’s giving ample time to get the PSC steering done.


On the gearing topic. Diesel on 37’s and 3.73’s will be going to 4.88’s for 40’s, 4.56’s would probably be enough but 4.88’s give a bit more with for 200 more RPM’s slight mechanical advantage > .5mpg gain
3.73’s are fine if you are around town, unloaded and not crossing mt pass’ weighted down and or towing you will want deeper gears. -argue about it… it’s your jeep, you do you…

 

[Billkowski]

I would suggest the weight of these "37s" greatly impacts the variance of opinions here, they are anywhere from 65 to over 100 lbs depending on the brand. Never underestimate the impact of additional rotational mass on performance.

 

[RubiWhiteGladiator]

Own a 21' Gladiator Rubicon, Was running factory 33s with 4.10 with bed cap and RRT and custom box in back with gear. Would see 7th or 8th on flat or down hill. Switched to 3.5 inch lift with 37s and was even worse. Would get lucky with a tail wind and down hill. Switched over to 5.13 and couldn't be happier, wish I done it sooner. Honestly depends on your set up and what you have re-gearing might or might be worth it. With the 5.13s I see 7th and 8th no problem and have gotten better MPG also. Live in SoCal area.

 

[1550jrit]

I’ve been meaning add these pictures as a point of reference for those looking to re-gear. I am running 5.38’s with 37’s so those who go with 5.13’s will have slightly lower RPM’s for the given speed.

At 85 mph, I’m at roughly 2900 RPM. Considering that I still have 3500 RPM redline and I’m sitting at the bottom of the motor’s power band, it’s acceptable trade off to me for the deep gears. My only concern going this deep was staying in the 1st stage of the oil pump when cruising, which I can do if I stay at or below 85 mph.

About the only time I cruise at 85mph is going across South Dakota where the speed limit is 80mph. The truck easily holds 85mph loaded down and I even took a reading of my diff temps after cruising 8 hours straight. To the best of my recollection, my diffs were approximately 150- 160 degrees, something like that. Overall I’m super happy with the performance and drivability of the 5.38’s.

This information is simply being added as a point of reference for those considering re-gearing. I have zero cares as to whether or not someone chooses to run 3.73, 4.10, etc with 37’s or how someone chooses to spend their money. No points being proven here, just information being shared.

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