Gas milage and drivability of 4.10 Rubicon gearing vs 3.45 Sport gearing

[TIDALWAVE]

The new Teraflex video states that their JLUR got 16+ mpg during Interstate speeds (80mph) on long distance trip. The other odd statement, perhaps incorrect, said that the gas tank was 24+ gallons.

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[wanderer]

hey enough about finances it s cool and all bu this thread is titled gas mileage and drivability Thanks

 

[wanderer]

yes but that is at 55 in perfect conditions. I once got 30 going down hill out of flag staff with a tail wind. but I usualy get 12-14

 

[Dynomite1371]

My reading shows 16.5 on my JLUR and that's with, the tank it came with, probably not topped of, and I personally have at least 3 hours of idling (1 hour with salesman after it came in showing me all the options and settings I radio, 1 hours of me tweaking things in the system, 1 hour last night of more tweaking and figuring things out and setting up the visor garage door opener and getting logged on with free year of Guardian service) 2 hours of trails in 4 Wheel drive and 200 miles of highway @ 65 mph. So I'm going to fill it up for the first time tomorrow, I'm still showing over a quarter tank! It can only get better.

 

[The Great Grape Ape]

80MPH is significantly more drag than 60MPH, the Wrangler needs to provide more HP to overcome wind resistance. I’ve mentioned it a few times here before that when I was going across country this year, twice I couldn’t keep the speed limit (~75MPH) so I had to go ~2MPH under because the JKU was wanting to hit 4K+ RPM to maintain that speed and fuel economy would crater from about 17-19 MPG down to 12MPG.

Likely a similar scenario for Teraflex above, where in order to do 80MPH with whatever setup they had, they had to leave the sweet spot, and couldn’t just cruise at 1,700 RPM like they would in EPA testing.

 

[The Great Grape Ape]

Yeah, quoted EPa numbers are from the test that peaks at 60MPH, and averages 48MPH

They do have a HighSpeed test that peaks briefly at 80MPH a few times (but has a similarly low avg), however that data is rarely provided.

https://www.fueleconomy.gov/feg/fe_test_schedules.shtml

Also their tests on the stickers changed in 2017 so they aren’t relatabled theoretically from pre-2017;
https://www.fueleconomy.gov/feg/ratings.shtml

But for the practical purpose, we get what we get when we drive, so real world vs real world would be the same.

They were driving a stock Rubicon w/ auto. That is pretty poor gas mileage even for a Rubicon. My TJ gets about 16 mpg at 70 mph. Just wanting enough MPG to get home without a fill-up. I've gotten used to the rentals which are keeping about 30-35mpg at 80-90mph. They don't seem to take much hit.

Yeah, I agree, especially when on long cross-country trips where MPG matter over 17,000 KMs so the 5MPG hit for a few hours in NFLD and Sask would have been more of an issue than the 15mins driving through town around the ring road, etc. But eventually it all adds up.

The Rubicon of course pays a price for the hiher axle ratio, but one would think the impact is lower on the JL with the wider spread and lower OD ratio of the Auto being able to keep it in a sweeter spot than the prefious 5 & 4 spd autos.

 

[wanderer]

What is the gear ratio of the highest gear on the 8sp auto vs the 6th on the manual on another thread here someone said 5th felt like an od

 

[The Great Grape Ape]

What is the gear ratio of the highest gear on the 8sp auto vs the 6th on the manual on another thread here someone said 5th felt like an od

ZF8 Auto

• 1st - 4.71
• 2nd - 3.13
• 3rd - 2.10
• 4th - 1.67
• 5th - 1.28
• 6th - 1.00
• 7th - 0.84
• 8th - 0.67

I had been hoping for the 5.00 - 0.64 version of the ZF8, but this is still much better than the outgoing ones.

Aisin D478 Manual

• 1st - 5.13
• 2nd - 2.63
• 3rd - 1.53
• 4th - 1.00
• 5th - 0.81
• 6th - 0.72

Not a huge difference in the final gear of either (though bigger 7-8 in the ZF than 4-5-6-7), but then again Dan said he wasn’t pushing his new JL yet until it was properly broken in, so the need for 6th below 50MPH would be limited, even in his Rubi.

 

[Dynomite1371]

True that reading is real time mileage, often times, depending on your driving habits, when you fill up and do the math that reading is right on. I will fill up today and keep you posted.

 

[DanW]

ZF8 Auto

• 1st - 4.71
• 2nd - 3.13
• 3rd - 2.10
• 4th - 1.67
• 5th - 1.28
• 6th - 1.00
• 7th - 0.84
• 8th - 0.67

I had been hoping for the 5.00 - 0.64 version of the ZF8, but this is still much better than the outgoing ones.

Aisin D478 Manual

• 1st - 5.13
• 2nd - 2.63
• 3rd - 1.53
• 4th - 1.00
• 5th - 0.81
• 6th - 0.72

Not a huge difference in the final gear of either (though bigger 7-8 in the ZF than 4-5-6-7), but then again Dan said he wasn’t pushing his new JL yet until it was properly broken in, so the need for 6th below 50MPH would be limited, even in his Rubi.

Yep. I doubt I'll drop 6th until 55mph, and that is if I'm cruising. I'm pretty sure I'll only drop 6th when I hit the desired cruising speed, whether it is 60, 65, 75, or whatever. I won't accelerate with it, only cruise, especially when I go to 35's. It feels TALL.

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