3.73 only in eco? 37’s

[Wrangler man]

Started with 33s went to 35, to 37s and now found the new sweet spot, 38s. Running Banks Derringer and Pedal Monster. I have more than sufficient torque and power with the benefits of better MPGs on the highway. Owned several sport or sporty cars quick off the line including my daily driver BMW. I'm not interested in 0 to 60 or trying to get anywhere fast when driving the EcoDiesel. My build had all intentions of being most functional and capable off-road. I agree that the EcoDiesel Powertrain platform with the 8-speed automatic is the best option of all Wranglers. When running flat highway speeds my Wrangler is still able to utilize 8th gear on its own. And when rock crawling or very challenging obstacles manual mode is a must and of course 4low. Once again giving me plenty torque and power when needed.I do agree M1 is a monster giving you all you need with the Eco diesel torque. Not having a rubi if I was to upgrade it would be Rubi transfer case with OEM 4:10s. Anything else would be excessive only resulting loss in fuel and MPG.

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[Adv_aw8s]

I regeared ours to 4.56's in 37's and would do it again in a heartbeat. We live at altitude in Colorado and tow an off-road trailer part of the time. We ran the jeep for 10k miles on 37's before we regeared and it wasn't horrible but we weren't towing either.

 

[Terpsmandan]

I am running 37” KO2’s with 3.73 gears and a GDE tune. I did not even consider a re-gear because of the torque the EcoDiesel puts out and with the tune I get approx 500 ft lbs at the crank and GDE removes the lower gear torque limiter. Been wheeling a few times and never was at a loss for get up and go.

 

[JLURD]

People regear to force the engine to develop more RPM's at a given speed. The reason for doing this is to get the engine into a higher torque band. This is most important starting from zero MPH continuing thru each gear as the transmission shifts. Running at highway speeds, you are not really wanting higher RPM's as that burns more fuel.

So the question is, do you have insufficient torque to get you moving? Fortunately, you have a diesel which develops high low end torque and provides it at a consistent level across all normal operating ranges.

To get any Jeep moving without stalling, you must rev the engine to about 1200 -1400 RPM. Your torque converter is doing this work for you. It also has a stator that is magnifying your torque at low RPM's. (A manual transmission does not have a torque converter and is why most Jeep owners like automatics, whether they know why or not.)

So, let's look at the numbers for your engine and all the others. At 1400 RPM your diesel develops its peak torque of 442.5 lb/ft. It keeps it there up to 2800 RPM and decreases slightly above this. At 1400 RPM the 2.0 develops 163.9; the 3.6 170.0; the 392 hemi 311.9 and the 4xe 261.0.

The diesel wins. The diesel is simply the best engine ever put in a Jeep to do Jeep things, all other things being equal (which is not the question here).

Now to your question, do you need to regear with 37's. No. The torque converter raises your RPM's as needed to start, you start in MAX TORQUE with 33's or 37's and stay there throughout operating ranges.

I actually found that going to 37's helped to control some of the "excess torque" in low range while rock crawling with the stock tires. You might also note that in 4 wheel low, your automatic will start in second gear rather than first to control some of this excess torque. You can always drop into manual shift and go to first gear if you want higher RPM's (much easier than regearing).

And by the way, if you are worried about the torque dropping after 2800 RPM in your diesel, you will be going 122 MPH in 8th gear with BFG KO2's 37".

This. I ran my 3.0 on 37s for 70,000 miles at 6000lbs on stock 3.73 through every type of terrain from Moab to the Brooks Range. Towed with it, raced a 392, wheeled it onto icebergs, did 8000 mile road trips twice. Holds 8th in the mid 50s, turned 22-23mpg all day long and does all of the above much more effectively than my 3.6 with 4.10s ever did, for all of the above-noted objective reasons. Now I’m over 600lb-ft with it and gearing is even more irrelevant. The vast majority of people regearing 3.0s are buying zero objective performance benefit at the price of gears and extra fuel burn.

 

[Wrangler man]

This. I ran my 3.0 on 37s for 70,000 miles at 6000lbs on stock 3.73 through every type of terrain from Moab to the Brooks Range. Towed with it, raced a 392, wheeled it onto icebergs, did 8000 mile road trips twice. Holds 8th in the mid 50s, turned 22-23mpg all day long and does all of the above much more effectively than my 3.6 with 4.10s ever did, for all of the above-noted objective reasons. Now I’m over 600lb-ft with it and gearing is even more irrelevant. The vast majority of people regearing 3.0s are buying zero objective performance benefit at the price of gears and extra fuel burn.

Real world results. There's opinions, feelings and then there's facts. Thanks for sharing.

 

[Terpsmandan]

This. I ran my 3.0 on 37s for 70,000 miles at 6000lbs on stock 3.73 through every type of terrain from Moab to the Brooks Range. Towed with it, raced a 392, wheeled it onto icebergs, did 8000 mile road trips twice. Holds 8th in the mid 50s, turned 22-23mpg all day long and does all of the above much more effectively than my 3.6 with 4.10s ever did, for all of the above-noted objective reasons. Now I’m over 600lb-ft with it and gearing is even more irrelevant. The vast majority of people regearing 3.0s are buying zero objective performance benefit at the price of gears and extra fuel burn.

That is why I never considered re-gearing. I was always of the opinion that you regeared to compensate for the lack of torque (early JK with a 3.8). With the GDE tune I have 550 ft lbs at the crank at 1600 rpm.

 

[aristobrat]

Holds 8th in the mid 50s

mid 50s = mph?

 

[JLURD]

mid 50s = mph?

Correct.

 

[ChuckQue]

Oddly enough, there’s quite the dispute on the Eco groups regarding low rpm torque causing bottom end issues with these motors. Most of them do agree that driving them with kids gloves isn’t good for the eco. Bearings and all that.

 

[RicRecon]

Oddly enough, there’s quite the dispute on the Eco groups regarding low rpm torque causing bottom end issues with these motors. Most of them do agree that driving them with kids gloves isn’t good for the eco. Bearings and all that.

Which Eco groups are you referring to? I’d like to visit these links.

 

[ChuckQue]

Which Eco groups are you referring to? I’d like to visit these links.

www.ram1500diesel.com is one, the others are Facebook groups. Lots of good info in there, and lots of nonsense

 

[RicRecon]

www.ram1500diesel.com is one, the others are Facebook groups. Lots of good info in there, and lots of nonsense

I was under the impression that the ED put in the 2020-24 Jeeps were a 3rd generation motor and didn’t exhibit many of the issues inherent with the previous generation used in the Ram pups.

 

[ChuckQue]

I was under the impression that the ED put in the 2020-24 Jeeps were a 3rd generation motor and didn’t exhibit many of the issues inherent with the previous generation used in the Ram pups.

Correct, you’ll have to deep dive to find 3rd gen relevant stuff. It’s like drinking from a fire hose on that forum.

 

[zouch]

i went with 4.56s for 37s in an attempt to keep everything spinning/lubed/cooled at the appropriate RPM for the load.

4.56s are mathematically the closest i could get with the gear choices i could find available from reputable manufacturers. (something around 4.32 would have been nice.)

3.73s were tolerable on 35s, but it no longer felt right once i went to 37s. drivability on and off-pavement was much improved with 4.56s.
MPG is still in the low 20s in typical driving, but drops to near 20 at high Western highway speeds (80+).

I didn’t realize 3.0 only came with 3.73
with 37’s where are these eco’s happy?

 

[grimmjeeper]

i went with 4.56s for 37s in an attempt to keep everything spinning/lubed/cooled at the appropriate RPM for the load.

4.56s are mathematically the closest i could get with the gear choices i could find available from reputable manufacturers. (something around 4.32 would have been nice.)

3.73s were tolerable on 35s, but it no longer felt right once i went to 37s. drivability on and off-pavement was much improved with 4.56s.
MPG is still in the low 20s in typical driving, but drops to near 20 at high Western highway speeds (80+).

I still believe (with no hard data, just opinion) is that the only reason the base gears were 3.73 is because 3.45s aren't available for the front M210.

Given that assumption, 3.73s are good for 35s and 4.10s are good for 37s.

I loved the 3.73s with my 35s. I would prefer 4.10s with my 37s but not enough to drop the cash.

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