Regearing a 2010 JKUR

[Rovertrader]

Thanks!! And back at 'ya ;-)

 

[DreamingOfExpeditions]

Maybe your all right. California uses Oxygenated gasoline. Don't know about the other poster. EPA mandates it in city areas. Here in NJ our milage suffers because of it.

 

[mvbeggs]

Keep the weight down.....True Dat!

...The garage shot is most recent, but the jest of it is to keep the weight low!! I replaced the cable with rope, got rid of the KM2s, etc. I do have HD axles, lockers, etc but nothing adding weight that isn't a must...

I agree with Rovertrader on the weight issue. As for the gas mileage everyone else is getting...I can only dream.

 

[mvbeggs]

2011 Rubicon-

:sombrero: Heh Heh, sorry, but no JKUR ever weighed 2011 lbs--...

:costumed-smiley-007:wings: JIMBO

Pretty funny Jimbo. The year of manufacture was 2011 not the weight. When I reread my post it was a little confusing. :elkgrin:

 

[JIMBO]

:sombrero: I can't really agree with you when you're talking about saving weightt--the average weight of a slightly modified JKU--is generally 4600lbs, then you add two people and some gas/gear, it adds up to 5000 lbs--

If you sacrafice all your dreams and desired mods-and save 500lbs !!

You may be talking about 1 to 2 mpg--your driving technique alone can makeup for that--

My '08 JKUR(4.10) gears, in stock condition, driving to Los Angeles, averaged 16/17 mpg at 4600 lbs--that was 3 years ago-

Now/w 5.38 gears avg weight 5200 lbs avg mileage 15/16 mpg--

Saving weight may benefit in a JK at 3900 lbs, but there's too many positive mods you can do to a JKU for safety/versatility/adventure overlanding

and convenience-

Yeah, over 100,000 miles there will be a slight financial loss in 1 mpg costs, but isn't that a little idealistic ??

It's a jungle out there
:costumed-smiley-007:wings: JIMBO

 

[Rovertrader]

I really don't want to start an argument, but in the end it is all cumulative. The weight is part of the factor- but which weight and where is just as important. The bumpers are the furthest distance cantilevered past the axles(hence my switch to rope from cable- long fulcrum) and they affect the drag immensely. Same with tires- M/Ts bite at the air just like they do the mud. A/Ts added better aerodynamics, and a bit less unsprung weight.
In the end, all these little bits add up, and accent themselves by the driving style of the driver. The other added benefit is less wear and tear on the vehicles. Minimal perhaps, but again multiplied by the miles and style...
Here is a big example of how much the multiplier matters: would you rather receive a million dollars, or a penny, and double the penny each day for a month, keeping the cumulative result? 1,2,4, 8, 16, 32, 64 for the first week... $1.27, and only 24 days to go!

 

[JIMBO]

:sombrero: I don't have any doubts about your weight/mileage examples and I sure wouldn't argue about something as basic as that,but

I really don't want to start an argument, but in the end it is all cumulative. The weight is part of the factor- but which weight and where is just as important. The bumpers are the furthest distance cantilevered past the axles(hence my switch to rope from cable- long fulcrum) and they affect the drag immensely. Same with tires- M/Ts bite at the air just like they do the mud. A/Ts added better aerodynamics, and a bit less unsprung weight.
In the end, all these little bits add up, and accent themselves by the driving style of the driver. The other added benefit is less wear and tear on the vehicles. Minimal perhaps, but again multiplied by the miles and style...
Here is a big example of how much the multiplier matters: would you rather receive a million dollars, or a penny, and double the penny each day for a month, keeping the cumulative result? 1,2,4, 8, 16, 32, 64 for the first week... $1.27, and only 24 days to go!

The reasons I gave and the reason forem is, I don't consider the mileage--at all; only the performance of my JKUR and the "end weight" is the reason I have very light bumpers and use mobile winchs---

We have a lotta different ideas/visions/uses for our jeeps and we should accept that-

:costumed-smiley-007:wings: JIMBO

 

[Rovertrader]

We have a lotta different ideas/visions/uses for our jeeps and we should accept that-

:costumed-smiley-007:wings: JIMBO[/QUOTE]

With that I totally agree!! Cheers

 

[mvbeggs]

More Info Please

I don't consider the mileage--at all...

I didn't either until I had to stop every 200 miles for fuel! :Wow1:

...We have a lotta different ideas/visions/uses for our jeeps and we should accept that-

:costumed-smiley-007:wings: JIMBO

Couldn't agree more.

Back to ccfdal's (the OP) original question regarding gearing while pulling his trailer. Where do you plan on traveling and how far away from home are your trips going to take you? (are you crossing multiple states to get to the trails you want to run, does it require running over high mountain passes, do you plan weekend trips or extended back country stays, etc) Are you mainly going to run unimproved roads/dirt and gravel roads, or do you need to tackle serious terrain? Is this also your daily driver? How much weight do you put in the Jeep when heading out into the back country? How fast do you want to travel on the highway and what is your upper limit for extended highway cruising RPM's? Additional details on how you plan, or want, to use your Jeep would be very helpful. IMHO, a vehicle build is always a compromise between trail capability and "on road" manners. Just need to know your priorities.

 

[Yuman Desert Rat]

Interesting thread. I envy all of you and your high gas mileage. My pig (06 LJ) is about as aerodynamic as a cinder block and gets better mileage driving off road than on the highway. The Genright Safari 31.5 gal tank was my solution, lol. I believe they make an aux tank for the JK as well. Call and ask for Keith Lyon he's a good dude and can sometimes cut you a better deal than what's advertised.

 

[iRagedoYou]

I to am getting 17-18 mpg consistently.However, I cannot comment on going 80, as I haven't. On the other hand I built a bit different this time- stock shorty front bumper, factory rear bumper w/ AEV tire carrier, and running A/Ts, as well as AEV programer. Nice and quiet, smooth, and decent mileage- and I have a small roof rack- well, here is mine:

The garage shot is most recent, but the jest of it is to keep the weight low!! I replaced the cable with rope, got rid of the KM2s, etc. I do have HD axles, lockers, etc but nothing adding weight that isn't a must...

Rovertrader: Your Jeep looks great!!

 

[wADVr]

Old thread but have a couple observations with JK gearing, coming from an XJ guy.

My XJ with its low end torquey 4.0l ran its best with 4.88s and 33s. Best mileage, power, etc... With 35s everything dropped slightly. But I will show the numbers for comparison:

33s
4.88s @ 60mph = 2250 rpm
4.88s @ 70mph = 2625 rpm

35s
4.88s @ 60mph = 2120 rpm
4.88s @ 70moh = 2475 rpm

Stock 28" tires with stock 3.55s @ 60 = 1930 rpm and @ 70 = 2250 rpm


Now the heavier JK with its less low end powered 3.8:

35s
5.13s @ 60mph = 2050 rpm
5.13s @ 70mph = 2390 rpm

5.38s @ 60mph = 2150 rpm
5.38s @ 70mph = 2500 rpm

Stock 32s with stock 4.10s (rubicon) @ 60 = 1793 and @ 70 = 2092rpm


While the factory rpms of the JK are lower I don't think the 3.8 handles the additional weight well and should be over geared to compensate to gain back any efficiency and power. Even though the swapped in axle ratios are deeper in the JK the 4th gear in the auto box is higher so it is still a higher overall ratio which lowers the PRM, thus lower on the torque curve and away from peak effiency. I would think 5.38s with 35s would be minimum recommended ratio, unfortunately it is the lowest available. I currently have 5.38s with 37s and wish it was a little deeper, I believe I would see an increase in performance and mileage as I experienced with the XJ.

All this being Auto equipped of course.