Diesel Gladiator owners with upgraded gearing ONLY please...

[cotnballs2000]

Weird, found plenty of posts in JL forums about guys recommending regearing with diesels. Most don’t because of expense and the fact that the diesel does tolerate tire changes better than the 3.6. Hell, AEV recommends 4.56’s for 37‘s for their builds on Ecodiesels. The diesel “tolerates“ the changes in tire sizes better but running 3.73‘s with 37’s is less than ideal. Lot of it depends on what you’re doing. I tow a camper that pushes 5000-5250 lbs so I’ll be trying 4.56’s on 35’s. I see lots of claims that he 3.0 makes peak torque at 1400-1500 rpms, actual dyno graphs show the number peaks over 2000 rpm…
With 4.56s and 35’s I’ll be running barely over 2000 rpms at 70 mph.
3.73’s and 31’s had me at 1850. Sorry I don’t have real world experience as my gears and ARB’s have been purchased but not installed. Hope to remedy that very soon and I’ll report back ?

You are getting wrap around dyno numbers you don't understand. Those dyno number are done at wide open throttle in 7th gear. They are lugging the engine at low speed before they start the pull and engage the 2600lb roller on the dyno. That’s why you see the low torque numbers below 2000 rpm(also you are not taking in account the torque converter in the auto transmissoin and the inaccuracey of the dyno with low RPM). Dyno numbers mean absolutely nothing in the real world but max hp and torque gains on the upper end when compared to the stock run. Re-gearing the rear end doesn’t add a torque multiplier it just moves your RPM in a particular gear up or down. When you put larger tires on it drops your RPM in all gears, when you put a large numerical gear in it raises your rpm. If you want to spend the money re-gear. Do the math and see what RPM change you want to live with and the cost to benifit of doing so for yourself. I ran 4.88 with 33" tires on my JK just because it was standard with the RockJocks I wanted, it drove fine by suffered in MPG and engine noise at hwy speed.

https://www.motortrend.com/news/dyno-testing/

Sponsored

 

[Jocww]

My mpg actually improved after regeared to 4.10s. I'm sure it's from less loading/lugging the motor.

why wouldnt u just down shift then to prevent loading?

 

[M390]

You are getting wrap around dyno numbers you don't understand. Those dyno number are done at wide open throttle in 7th gear. They are lugging the engine at low speed before they start the pull and engage the 2600lb roller on the dyno. That’s why you see the low torque numbers below 2000 rpm(also you are not taking in account the torque converter in the auto transmissoin and the inaccuracey of the dyno with low RPM). Dyno numbers mean absolutely nothing in the real world but max hp and torque gains on the upper end when compared to the stock run. Re-gearing the rear end doesn’t add a torque multiplier it just moves your RPM in a particular gear up or down. When you put larger tires on it drops your RPM in all gears, when you put a large numerical gear in it raises your rpm. If you want to spend the money re-gear. Do the math and see what RPM change you want to live with and the cost to benifit of doing so for yourself. I ran 4.88 with 33" tires on my JK just because it was standard with the RockJocks I wanted, it drove fine by suffered in MPG and engine noise at hwy speed.

https://www.motortrend.com/news/dyno-testing/

I guess somebody needs to try running some 2.73 gears on stock sized Gladiator Sport tires to see what kinda mileage we get at cruising speed just below 1400 rpm’s ?
I got way better mileage with the motor turning in the 1900 rpm range in 8th gear on stock tires at 70 mph than I do now with it spinning at 1650ish currently on 35’s. Gearing my Jeep to 4.56‘s puts the rpm range barely over 2000 rpm’s at the same speed. I understand what I intend to attempt to accomplish just fine. The logic is completely sound. My intent is reasonable mileage and better pulling power combined. I’m done debating on my end. Time to install my 4.56’s and see what happens. Wether I regret it or not I’ll report back with my findings.

 

[Vtur]

why wouldnt u just down shift then to prevent loading?

No issues with around 40 mph+. It's the stop and go that's lugging the motor.

 

[Vtur]

I got way better mileage with the motor turning in the 1900 rpm range in 8th gear on stock tires at 70 mph than I do now with it spinning at 1650ish currently on 35’s. Gearing my Jeep to 4.56‘s puts the rpm range barely over 2000 rpm’s at the same speed. I understand what I intend to attempt accomplish just fine. The logic is completely sound. I’m done debating on my end. Time to install and see if it works for real ?

Exactly right. Higher rpm with less of a load to the motor consume less fuel. Don't gets carry away with lower rpm will magically uses less fuel, it ain't.

Those who haven't regear said it's not needed, but those who regeared are happy with their decision and I'm one of them.

Axle gearing is just the final ratio. Some even compared the Gladiator 3.73 to something with a totally different motor and tranny ratios per gear sets.

Waiting for those that's gonna regear soon to report back.

 

[kilroy173]

What's the general consensus on 35s with stock gearing on stock wheels? Especially since most 35s measure closer to a small 34 or large 33?

 

[rharr]

What's the general consensus on 35s with stock gearing on stock wheels? Especially since most 35s measure closer to a small 34 or large 33?

DO THE MATH, USE THE GEAR CALCULATORS, PICK A CRUSING RPM YOU ARE HAPPY WITH.

 

[kilroy173]

DO THE MATH, USE THE GEAR CALCULATORS, PICK A CRUSING RPM YOU ARE HAPPY WITH.

THANK YOU! THIS WAS VERY HELPFUL!

 

[M390]

4.56’s/ARBs finally installed. My rig is on 35” tires. Been breaking them in mostly but I saw 18.5-19 mpg bucking a 10-11 mph head wind on the 100 mile drive back to my home town from the shop that installed them running 75. Mileage seems at least as good as it did with 3.73’s. It holds 8th gear waay better than it used to on even long steep grades. Pulled my 25 ft. R-Pod today finally, weighs in around 5000ish lbs wet. Very pleasantly surprised in how it affected the EGTs. The mechanical advantage of the gearing keeps the boost down a bit and I see as much as a couple hundred degrees less towing at 65 mph. Early yet, but loving it so far and by no means do I feel like I over geared it at all.

 

[Orangecrush03]

I've read the many responses and had to finally chime in. For those of you using a gearing "calculator", simply don't. That calculator will get you in the ballpark. You can do the same mathematically comparing your gear ratio to the tire size you had and what you want.

The reason I said don't is because mathematically (or through the use of a "calculator"), those numbers would work great IF the wheel and tire size were the same. The extra energy needed to turn over bigger tires doesn't reflect on daily driving. Even people that rely on using a dyno are somewhat misled. Not everyone leaves the light in 4th gear and WOT. Having said that, figuring the correct gear ratio doesn't account for the extra weight also that a larger tire has.

I'm on my second gladiator, my first 2020 with a 3.6 and a hamburger supercharger didn't have the torque necc to tow my needs. My latest gladiator up until yesterday was running 37's with 4.10 gears (with a Banks tuner producing 350 HP and 513 FT LB at the wheels)

Early in the beginning I had swapped axles with a friend that had a non diesel Rubicon because he was going to regear anyway and I wanted a tad more than 3.73's.

4.10's did the job. If I could have gone to a 4.30'ish, it would have been even better. I have a 50 mile one way trip to work and running in the higher 70's to mid 80's, I'm getting roughly 20 mpg. I've been running this setup for over 25K miles.

Now that I have installed 38's, I see I'll have to definitely upgrade. I can feel the difference and already see a drop in mileage of 1-2 mpg with the 38's and 4.10s.

My point in this conversation is that you can't rely on calculators, theoretical numbers because at the end of the day, how it feels with your butt in the seat is what counts.

You can run 37's with the stock 3.73's but you'll see less of 8th gear than you'd like on the highways. 4.10's is a happy medium but I think 4.56 is the way to go with 37's and up.

My real world .02 worth...

 

[Chance575]

Just finishing up with my 4.88 install. Stuck waiting on a new passenger side axle. I was able to locate new rear seals but could not get to them with my bearing spliter. I was unable To source new bearings so im waiting on a shaft from eBay.

that said I think I’ll be happy with 4.88s and 37s. Planning on towing a travel trailer or car trailer with it

 

[M390]

Run from Austin to W TX. Flat road, zero wind, cruise set at 75.
This is with 4.56’s and Yokohama 35’s. Gearing calculator I used was dead on for speed/rpm with 4.56’s. Everything is properly adjusted for gearing, tire size, and shift points with my Tazer.

 

[Orangecrush03]

Your glad is a diesel, right?

 

[M390]

Your glad is a diesel, right?

Yes

 

[Vtur]

Here's my reading while on a 1500 miles road trip around the SW, CA, NV & AZ.

Sponsored