Brand New 2023 Rubicon Ecodiesel want to run 37 need to regear to 4.11 or 4.56?

[fourfa]

I wish people would read the post, not just the topic… “Have dually for towing.” OP, 95% odds you’ll be just fine with stock axles for the use you describe. I’ve been very happy with a heavy overlanding/camping build on 3.73s, including long road trips, crawling, high speed washboards, low range, 75+ interstate, the whole range. I see 8th gear plenty, up to 75mph flats on the highway (over that, the aerodynamics of my over-the-cab camper take over and it needs 7th - stock should be more like 80).

Definitely try it out before budgeting for gears. Maybe you can find a local Jeeper willing to swap their 37s on for an afternoon, and see how it feels. I did notice a bit more turbo lag with mine, not bothersome but I noticed.

One option if it does bother you is a throttle controller for ~$100; these can improve the lag a bit as the stock throttle has a bit of delay programmed into it for fuel economy (we on this forum believe anyway). Many here have noticed a bit sharper throttle tip-in with these controllers (completely apart from their usual function of remapping throttle % vs engine power %). I did.

The throttle mapping can be fun to play with for a couple minutes. The various sporty modes just make the throttle very binary and lurching. I keep mine in the slowest possible Eco mode 100% of the time FWIW. All the power is still there, it’s just deeper on the pedal.

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[Steven_B]

BFGs are known to run a bit smaller, save money, and use it for another upgrade.

For reference, here are the RPMs with 4.10 gears and 37" Nitto Recons (my diesel JT).

 

[kosinar]

Well, then what @RhinoJT said. Throw those 37's on and see. A lot of folks on here did just that and are happy with the performance.

I have 2020 Wrangler Rubicon and 2023 Gladiator. Both are EcoDiesel and running 40" Cooper STT pro on KMC 17-inch KM235 Grenade bead locks. Both have a plenty of power and torque with 40's. Wrangler went through most of Moab and pretty much all of Ouray trails without regearing. Never felt I need regearing. I did not have a chance to do any off-roading with Gladiator yet, but I have no doubts it will do just as well as Wrangler. I would not waste money on regearing. If I wanted to spend any more money on my Jeeps I would spend it on stage 1 tune from MrTune in Canada. Supposedly add 50hp and more torque. I might consider it in the future but right now I am happy with performance of both Jeeps. I have opinion don't fix it if not broken.

 

[SGME9]

I run 37 Nitto Ridge Grapplers. I do rock crawling also here in Colorado. You do not need to re-gear.

 

[Iddpaul]

I just bought a JTRD last month and had the same dilemma. It really depends on what your "use" is going to be. If you're just "Mall Crawling" and staying with the smaller K02's then the factory 3:73 gearing "may" be ok for you (but as you said it will be "laggy" on power).

For me, I'm a believer in keeping the engine/transmission in the power band so consider a gear change as part of my build. I'm just finishing a Clayton lift and 4:56 Dana gears this week. So here's my logic from past experience. I've had plenty of Jeeps over the years, with my last being a "gasser" JLRU 3.6/Auto with 4:10's and 37's. I drove it for a few months and then re-geared to 4:88's, (a huge improvement for me and dollars well spent), if I'd been at higher elevation, or in the mountains I'd have gone with 5:13's.

Now let's talk about the Diesel 3.0/Auto. It comes with 3:73's and yes you can run it with 37's (and for some that would be fine), but you will be out of the factory intended power band. It will work but there's no doubt (even just doing the math) that performance/shift points/mpg/"driveability" will improve with a gear change. Ok, like you, I looked at 3:73 and considered 4:10's. For 35 inch tires 4:10's would be perfect, 37 inch tires and 4:10's will put you approximately "3% under geared" compared to the factory 33's and 3:73 gears. Unfortunately the issue always comes up, It's a chunk of money to spend only going from 3:73 to 4:10 especially if you stay on 35's (a 50/50 decision with the diesel in my opinion).

Now for my intended use, I'm towing a teardrop trailer and will be doing trails, East/West wherever I can go, as well as highway use. So the best gearing (math) is approximately 4:30's with 37 inch tires (and this ratio is not readily available). Decision time, go with 4:10 or 4:56 with the choice being better highway speed/rpm with 4:10, or towing/off-road and loose a little top end speed due to slightly higher rpms.

The 4:56 gears won out, the best choice for me with 37's and IMO dollars well spent as I'm "not" going super fast on the highway with the camper, and will keep the rpm's in check re the diesel (runs way lower rpms than a gasser), and I'll benefit with being in the factory intended performance range for the motor/tranny.

So to help your decision, I'd do as "Badunit" posted, and then once decided, do a gear change based on your use (and rpm range that you want to keep).

 

[Sperger]

I am running 4.56 with 40 inch Patagonias and KMC 17 inch desert beadlocks. Puts it within 100 rpm of factory and no issues with power. The 442 lb ft of torque really makes difference. Try it with the 37's, worst case you want more and go maybe 4.10s.

What lift did you use?

 

[RhinoJT]

I have a Rock Krawler 3.5 inch 3 link long arm front and the 3.5 inch x factor rear. As someone mentioned, I wanted a low CG lift with big tires. Also I have aftermarket fusion 60s, so I'm getting on the heavier side, (eventual JCR rear tire carrier and some sort of bed cage) hence why I wanted to re-gear. Sounds like you will most likely be fine with the stock gears and 37s.

 

[Sperger]

Depends on your driving style and preference. I like going fast and Immediately order a banks tuner and then regeared to 4.56 Dana spicers. Like the others suggested throw the 37” on and you will know if you want to regear or not. 4.10 gears would probably not be worth the couple thousands of dollars of expense , just my opinion. If you do long highway drives expect rpm to be higher around 2k @ 70mph. Overall I’m pleased with 4.56

 

[Sperger]

Any issues with the Banks with Jeep warranty?

 

[Sperger]

Thanks

 

[Sperger]

thanks everyone for your input. Lots of choices.

 

[SargeDiesel]

looking to run 37 K02 tires, not sure what lift yet, 2.5" Clayton or Mopar 2". Main thing is the gearing correct for factory like power or better. Thoughts? I have read a thread but was short and a couple of years ago. I read that the 3.73 are okay but laggy on power. Mostly mall crawler. Have dually for towing. might do some very light trails. No crawling. no overland.

Are you new to the forum or just new to 37's ? Either way, welcome. 37's in combination with the Diesel is just fine, no need to regear. No it does not lag... make sure you are hearing from people 1st who own the diesel and 2nd , that are running 37's without a regear. There is more that you can probably read in a night about the diesel/37's/regearing on this forum.

Every member that I have had contact with that actually have a diesel on 37's are more than satisfied without regearing, myself included.

 

[Ecodiesel gladiator]

Any issues with the Banks with Jeep warranty?

When ever I take it to the dealership for service I disconnect it from the ecu port , remove the tuner controller while hiding the wire inside the dash speaker grille , and 1 connection in the engine bay. It’s usually a 5-10min job. Don’t want to try my luck with the dealer. Reason I only remove those connections and leave the rest of wiring is because I have other wires (amp, rock lights, kc pillar lights, aftermarket aux switch, etc.) running in the same bundle of wires and the tuner wires blend in. I would recommend the banks tuner, I would say the biggest difference was the Banks pedal monster that works in conjunction with the tuner. It spools the turbo up much sooner. I only have about 6k miles on the jeep, so don’t know long term. Maybe someone else can chime in that has had it for longer period of time.

 

[Rusty PW]

Any issues with the Banks with Jeep warranty?

I unplug the Derringer and Pedal Monster. But leave the iDash gauge hooked up when I take it in.

 

[Jefe1018]

Does anyone with stock gears track mpg? Here is my Fuelly data over over nearly 24,000 miles. Keep in mind 90% of my driving is short commutes and city driving. I had someone tell me my numbers were misleading and not possible, not sure how hand calculations for 24,000 miles, 111 fill ups and over a two year period are completely irrelevant to reality.

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