Diesel Rubicon 3.73 Gearing With Larger Tires?

[beaups]

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.

Ah then I did miss it, thanks. This just goes back to the old misunderstandings about torque vs hp. All 3 powertrains have similar horsepower = all 3 powertrains will perform similarly. The difference being the 3.0 (and the 2.0 to a lesser extent) having more available power at first gear speeds.

And bringing back to topic, the same affect happens when regearing. More power available to the wheels in first gear speeds and a 50:50 mix of more and less power available to the wheels at other speeds.

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[PawsitiveTraction]

Here is the problem i have.
at 37" you will almost NEVER use 8th gear. Peak torque will roll in around 1500-1600, which means your best cruising rpm will be 1900-2000.
In 8th you would be running 92mph. 7th would be 72, and your direct gear would have you around 60mph.
You are going to see a lot of hunting for the appropriate gear at rural and highway speeds.

I think we are going to see a lot of people change for 4.10s or even a max of 4.56.

 

[JLURD]

Here is the problem i have.
at 37" you will almost NEVER use 8th gear. Peak torque will roll in around 1500-1600, which means your best cruising rpm will be 1900-2000.
In 8th you would be running 92mph. 7th would be 72, and your direct gear would have you around 60mph.
You are going to see a lot of hunting for the appropriate gear at rural and highway speeds.

I think we are going to see a lot of people change for 4.10s or even a max of 4.56.

That has not been my experience with 37s and 3.73 at all. It holds 8th with no hunting even at 65mph on slight inclines. Decent headwinds don’t seem to dissuade it from 8th either.

 

[PawsitiveTraction]

That has not been my experience with 37s and 3.73 at all. It holds 8th with no hunting even at 65mph on slight inclines. Decent headwinds don’t seem to dissuade it from 8th either.

im assuming you are at or just above sea level and on mostly level terrain?
the few dyno charts that are floating around the interwebs show the tq #s being less than 50% at 1400 rpms. Now dont get me wrong, im not saying your info is wrong in ANY way. im just curious if you are in fact in 8th at 65mph, as that would be right at 1400 rpm.

Cummins says my x15 makes max TQ at 1150. However the most effecient cruise comes in at 1450.

where is the redline on the ED?

 

[JLURD]

im assuming you are at or just above sea level and on mostly level terrain?
the few dyno charts that are floating around the interwebs show the tq #s being less than 50% at 1400 rpms. Now dont get me wrong, im not saying your info is wrong in ANY way. im just curious if you are in fact in 8th at 65mph, as that would be right at 1400 rpm.

Cummins says my x15 makes max TQ at 1150. However the most effecient cruise comes in at 1450.

where is the redline on the ED?

Redline is 4500. It’s most definitely in 8th because I’ve been switching it to manual mode to see the gear and figure out its shift point. Most times it’s shifting between 60 and 65mph within 2000’ of sea level. The pitch and roll won’t work at those speeds for me to tell you the incline it decides to shift at but we have some pretty hardcore inclines in AK that will push it to whatever gear it needs to maintain speed. Regardless, I’ve yet to see a compelling reason to swap gears for my use case. Maybe that will change when the lift goes on and the 4x4 work finds the limits.

 

[PhillybOlllllllO]

Not 40”s

 

[Razzer]

Phillibo...... Sry to butt in, ive been following this thread and I’m curious what your last post meant... not 40s? 40s are my plan for a DD, and wondering what you were saying. Thx

 

[Mr. Curti]

Razzer... if you are going to run 40’s, I’d strongly encourage you to go with 4.88 gears. With the stock tires and 3.73’s, calculations come out to 4.68. Now if you are just cruising around town, 4.56’s will probably be just fine. But if you are getting out in the rocks, mud, etc., then I’d say go with 4.88 gears.

I’m having my axles built with 5.13 gears and am going to be running 43’s. When I calculated it out, it calls for 5.03 gears, which I plan on using it in the rough, so I went with 5.13’s. Now if I was just cruising it, then I would have went with the 4.88’s.

I hope this helps you in your decision making.

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