Advertisement

Diesel Rubicon 3.73 Gearing With Larger Tires?

cyan2

Member
Joined
Jul 22, 2018
Messages
20
Reaction score
1
Location
Edmonton
Vehicle(s)
2019 Jeep Cherokee Trailhawk
More information on the diesel jeep got released this weeks. I have been looking forward to this. It was stated that the gearing ratio for Rubicon is 3.73, rather than the 4.10 on the 3.6 and 2.0. I'm planing to put a set of 35's on the Jeep, which is no issue for the 4.10 gearing on the 3.6 and 2.0. If the 3.0 diesel only comes with 3.73 gear ratio, would that be an issue to put on larger tires?



Advertisement



 

Headbarcode

Well-Known Member
First Name
Mike
Joined
Aug 16, 2018
Messages
1,326
Reaction score
1,362
Location
LI, New York
Vehicle(s)
2016 Nissan Juke SL awd (sold); 2019 JLUR Stingray 2.0 turbo
Vehicle Showcase
1
More information on the diesel jeep got released this weeks. I have been looking forward to this. It was stated that the gearing ratio for Rubicon is 3.73, rather than the 4.10 on the 3.6 and 2.0. I'm planing to put a set of 35's on the Jeep, which is no issue for the 4.10 gearing on the 3.6 and 2.0. If the 3.0 diesel only comes with 3.73 gear ratio, would that be an issue to put on larger tires?
With the higher torque rating, I don't foresee it being an issue to run 35's or even 37's with the 3.73 gearing.

It would've been nice if they had just left the Rubicon ratios as is. Unfortunately, maximizing fuel economy is the priority.
 

AnnDee4444

Well-Known Member
Joined
Jan 14, 2019
Messages
1,381
Reaction score
1,295
Location
Earth
Vehicle(s)
Jeep
It all depends on where in the RPM range it makes the torque. What it really gets down to is available torque at the axle. The peak numbers don't tell the whole story without the rest of the dyno chart.

I had a post a few days ago comparing the road force at the tires of a 3.6 manual vs 2.0. I hope to get information on the the 3.0 diesel soon, to see where it stacks up: https://www.jlwranglerforums.com/fo...6-and-manual-vs-auto.38517/page-2#post-856356
 

JLURD

Well-Known Member
Joined
Nov 30, 2017
Messages
1,316
Reaction score
1,600
Location
Alaska
Vehicle(s)
2018 Compass Latitude 6MT, 2020 JLUR 3.0
It all depends on where in the RPM range it makes the torque. What it really gets down to is available torque at the axle. The peak numbers don't tell the whole story without the rest of the dyno chart.

I had a post a few days ago comparing the road force at the tires of a 3.6 manual vs 2.0. I hope to get information on the the 3.0 diesel soon, to see where it stacks up: https://www.jlwranglerforums.com/fo...6-and-manual-vs-auto.38517/page-2#post-856356
442lb-ft at 1600rpm more than makes up the difference between 3.73 and 4.10 as it pertains to wheel torque.
 

AnnDee4444

Well-Known Member
Joined
Jan 14, 2019
Messages
1,381
Reaction score
1,295
Location
Earth
Vehicle(s)
Jeep
442lb-ft at 1600rpm more than makes up the difference between 3.73 and 4.10 as it pertains to wheel torque.
Do you have a source for that power figure? Everything I have seen has not specified a RPM @ maximum torque. I can find where the Ram's 3.0 calls out 1600 RPM, but nothing for the Jeep. I suspect that the Ram & Jeep's 3.0 are both ECU limited like the 2.0 turbo, and would have a wide RPM range where maximum torque is reached (The Ram's 480 lb-ft is exactly 650 NM, Jeep's 442 lb-ft = 600 NM, 2.0 turbo's 295 lb-ft = 400 NM... these even numbers aren't a coincidence). Because of this, I would think that the Jeep's 3.0 would achieve peak torque earlier than the Ram, and hold it longer. This would also explain the identical 260 HP rating (which is 379 lb-ft @ 3600).

Assuming the gear ratios will be the same (and of course the 3.73 vs. 4.10), here's how the road force of a 2.0 JLUR would compare to a 3.0 JLUR. The 2.0 is the dotted line, and the 3.0 is estimated a portion of the 3.0's torque 'curve' with the solid straight lines. I estimated using the two data points discussed above (442 lb-ft @ 1600 & 379 lb-ft @ 3600).
Pounds of road foce by gear (1).png

Edit: fixed the graph to show 8th gear & reverse.
 
Last edited:

AnnDee4444

Well-Known Member
Joined
Jan 14, 2019
Messages
1,381
Reaction score
1,295
Location
Earth
Vehicle(s)
Jeep
More information on the diesel jeep got released this weeks. I have been looking forward to this. It was stated that the gearing ratio for Rubicon is 3.73, rather than the 4.10 on the 3.6 and 2.0. I'm planing to put a set of 35's on the Jeep, which is no issue for the 4.10 gearing on the 3.6 and 2.0. If the 3.0 diesel only comes with 3.73 gear ratio, would that be an issue to put on larger tires?
Assuming the ECU doesn't limit boost by gear, you could run 40" tires on the 3.0 JLUR and have about the same road force as a 2.0 JLUR.
 

JLURD

Well-Known Member
Joined
Nov 30, 2017
Messages
1,316
Reaction score
1,600
Location
Alaska
Vehicle(s)
2018 Compass Latitude 6MT, 2020 JLUR 3.0
Do you have a source for that power figure? Everything I have seen has not specified a RPM @ maximum torque. I can find where the Ram's 3.0 calls out 1600 RPM, but nothing for the Jeep. I suspect that the Ram & Jeep's 3.0 are both ECU limited like the 2.0 turbo, and would have a wide RPM range where maximum torque is reached (The Ram's 480 lb-ft is exactly 650 NM, Jeep's 442 lb-ft = 600 NM, 2.0 turbo's 295 lb-ft = 400 NM... these even numbers aren't a coincidence). Because of this, I would think that the Jeep's 3.0 would achieve peak torque earlier than the Ram, and hold it longer. This would also explain the identical 260 HP rating (which is 379 lb-ft @ 3600).

Assuming the gear ratios will be the same (and of course the 3.73 vs. 4.10), here's how the road force of a 2.0 JLUR would compare to a 3.0 JLUR. The 2.0 is the dotted line, and the 3.0 is estimated a portion of the 3.0's torque 'curve' with the solid straight lines. I estimated using the two data points discussed above (442 lb-ft @ 1600 & 379 lb-ft @ 3600).
Pounds of road foce by gear (1).png

Edit: fixed the graph to show 8th gear & reverse.
I assumed the rpm from the Ram 3.0 figures. The JLU 3.0 may well reach peak torque earlier, but if it does, it won’t be by much. We’ll see.
 

Pootytanger

Well-Known Member
First Name
Mitch
Joined
Oct 8, 2019
Messages
100
Reaction score
226
Location
Louisville, KY
Vehicle(s)
2020 JLUR EcoDiesel
I installed BFG 37" KM3s today with AEV 2.5" lift. EcoDiesel handles these with NO PROBLEM. I doubt I'll regear.
 

Pootytanger

Well-Known Member
First Name
Mitch
Joined
Oct 8, 2019
Messages
100
Reaction score
226
Location
Louisville, KY
Vehicle(s)
2020 JLUR EcoDiesel

JLURD

Well-Known Member
Joined
Nov 30, 2017
Messages
1,316
Reaction score
1,600
Location
Alaska
Vehicle(s)
2018 Compass Latitude 6MT, 2020 JLUR 3.0
Oh that’s pretty af! Is it me or do you have some extra spring height remaining in the back to manage a heavier load without sagging? I’m thinking of putting their springs in but their rear bumper, tire carrier and fuel caddy is going to add a couple hundred extra pounds. Borahs look great btw!
 

beaups

Well-Known Member
First Name
Sean
Joined
Dec 6, 2019
Messages
283
Reaction score
301
Location
Ohio
Vehicle(s)
2020 JL
Do you have a source for that power figure? Everything I have seen has not specified a RPM @ maximum torque. I can find where the Ram's 3.0 calls out 1600 RPM, but nothing for the Jeep. I suspect that the Ram & Jeep's 3.0 are both ECU limited like the 2.0 turbo, and would have a wide RPM range where maximum torque is reached (The Ram's 480 lb-ft is exactly 650 NM, Jeep's 442 lb-ft = 600 NM, 2.0 turbo's 295 lb-ft = 400 NM... these even numbers aren't a coincidence). Because of this, I would think that the Jeep's 3.0 would achieve peak torque earlier than the Ram, and hold it longer. This would also explain the identical 260 HP rating (which is 379 lb-ft @ 3600).

Assuming the gear ratios will be the same (and of course the 3.73 vs. 4.10), here's how the road force of a 2.0 JLUR would compare to a 3.0 JLUR. The 2.0 is the dotted line, and the 3.0 is estimated a portion of the 3.0's torque 'curve' with the solid straight lines. I estimated using the two data points discussed above (442 lb-ft @ 1600 & 379 lb-ft @ 3600).
Pounds of road foce by gear (1).png

Edit: fixed the graph to show 8th gear & reverse.
What I don't think this chart addresses (or I'm misunderstanding it) is once the diesel winds out first gear, all 3 powertrains create ~the same wheel torque when in their lowest available gear due to the relatively consistent HP numbers in all the powertrains- i.e. lack of RPMs in the higher torque motors. For example,when the 3.0 hits second gear, the 3.6 is still in 1st. The 3.0 will have a 1 or 2 gear torque-multiplication disadvantage in every gear except 1st, which negates the engine torque advantage from a pure performance perspective.

I don't think there's any debating that having the power available at low RPMs is desirable in a Jeep, but it's ultimately the ~same amount of power as the other powertrains. More power at 1st gear speeds and less drama at other speeds.
 

Pootytanger

Well-Known Member
First Name
Mitch
Joined
Oct 8, 2019
Messages
100
Reaction score
226
Location
Louisville, KY
Vehicle(s)
2020 JLUR EcoDiesel
Oh that’s pretty af! Is it me or do you have some extra spring height remaining in the back to manage a heavier load without sagging? I’m thinking of putting their springs in but their rear bumper, tire carrier and fuel caddy is going to add a couple hundred extra pounds. Borahs look great btw!
You’re right, I do think I have a little extra height left. Maximus-3 rhino rack going on soon; it gets delivered today. Also adding RTT. I’d estimate 300lbs for these combined. I’d love an AEV bumper when it’s available. Also want RSE power running boards, which are like 150lbs I think. Honestly I think a winch bumper/winch would be fine too.
 

JLURD

Well-Known Member
Joined
Nov 30, 2017
Messages
1,316
Reaction score
1,600
Location
Alaska
Vehicle(s)
2018 Compass Latitude 6MT, 2020 JLUR 3.0
You’re right, I do think I have a little extra height left. Maximus-3 rhino rack going on soon; it gets delivered today. Also adding RTT. I’d estimate 300lbs for these combined. I’d love an AEV bumper when it’s available. Also want RSE power running boards, which are like 150lbs I think. Honestly I think a winch bumper/winch would be fine too.
When you install the Maximus 3 brackets, you don’t actually have to measure out the hole spacing on the roof and I think it’s honestly safer to just install the brackets, mark the centers of the bolt slots with a set punch from below, and drill the roof using the installed brackets as a guide...seems to get rid of any potential alignment errors.

ETA: The more I think back about that install, the more I’m convinced you don’t even have to take the roof off. The freedom panels have to come off, but I think everything else can be done with the rear hardtop on.
 
Last edited:

AnnDee4444

Well-Known Member
Joined
Jan 14, 2019
Messages
1,381
Reaction score
1,295
Location
Earth
Vehicle(s)
Jeep
What I don't think this chart addresses (or I'm misunderstanding it) is once the diesel winds out first gear, all 3 powertrains create ~the same wheel torque when in their lowest available gear due to the relatively consistent HP numbers in all the powertrains- i.e. lack of RPMs in the higher torque motors. For example,when the 3.0 hits second gear, the 3.6 is still in 1st. The 3.0 will have a 1 or 2 gear torque-multiplication disadvantage in every gear except 1st, which negates the engine torque advantage from a pure performance perspective.

I don't think there's any debating that having the power available at low RPMs is desirable in a Jeep, but it's ultimately the ~same amount of power as the other powertrains. More power at 1st gear speeds and less drama at other speeds.
It shows what you are referring to. Take 25 MPH for example: the 2.0 will have 500# more force than the diesel, because the 2.0 is in 1st gear while the 3.0 is in 2nd gear.

I should note that those power numbers are estimates, not from an actual dyno.
 

Advertisement






Advertisement




Top