The Big O JKUR build thread

[MTSN]

Not sure I agree with all the rotational mass figures

Here are the three setups I put into a spreadsheet using either manufacturer weights or my own bathroom scale to get figures. Total increase over the 315 Duratrac with spacers was only 8 pounds per corner, and from the factory setup it's only 26 pounds per corner. Yes there is far more at play than merely weight - there is the extra rotational mass which effectively increases the "lever" which is the tire by around 11% (factory tire measures 31.8" vs KO2 measuring 35.5"), but this setup is far easier on the drivetrain and the Jeep as a whole. Just for kicks, I added another table that shows how much more weight it would add to go to another popular wheel and tire combo - the Hutchinson Rock Monster and Toyo MT. It would have literally doubled the weight from the factory setup to go with that heavy combo in a 37" tire, and it would have still been 33 pounds heavier to with just a 35" Toyo vs. the 37" KO2. To use an AEV Salta wheel with a 35" Toyo would still be 12 pounds heavier than a 37" KO2, so people's assumptions that "you'll be fine with a 35 but everything will break with a 37" is completely missing the fact there are many, many variables and it does not hold true in all cases.

 

[kojackJKU]

Exactly. The biggest factor is the piece of equipement between the seat and the steering wheel!

 

[Longtallsally]

Well you certainly are putting a lot of thought into it, and are having fun, and that's all that matters. Plus it's yours, so gives a &$@ what I think.

No procal for me as I'm old school and have a stick (by choice when I ordered it). In 4 low and standing on the brakes, I can't stop or stall the vehicle in first gear and that crawl ratio being that much better (what is it, 85:1?) with the manual I'm now spoiled. With the weak sauce 2.73:1 T case in the YJ had me looking like Fred Astaire even with the hand throttle and correct axle gearing in Moab and on the Rubicon. Now, half the time I'm on the brakes even climbing with the JKUR. The slower the better IMO- keeps from breaking stuff and is more controlled.

Carry on, I'll go back to lurking...

 

[MTSN]

Well you certainly are putting a lot of thought into it, and are having fun, and that's all that matters. Plus it's yours, so gives a &$@ what I think.

No procal for me as I'm old school and have a stick (by choice when I ordered it). In 4 low and standing on the brakes, I can't stop or stall the vehicle in first gear and that crawl ratio being that much better (what is it, 85:1?) with the manual I'm now spoiled. With the weak sauce 2.73:1 T case in the YJ had me looking like Fred Astaire even with the hand throttle and correct axle gearing in Moab and on the Rubicon. Now, half the time I'm on the brakes even climbing with the JKUR. The slower the better IMO- keeps from breaking stuff and is more controlled.

Carry on, I'll go back to lurking...

Hey no worries didn't mean to come across as defensive! I probably overthought the decision and have tried to justify it with as many numbers as possible LOL. Truth of the matter I was getting a little bored and needed to turn the chapter on the build, so this was my motivation.

It's crazy how low first gear is in the manuals in 4 low! I'd love to go back to a manual, but my lower back and left knee tell me it's probably going to be automatics from here on out!

 

[kojackJKU]

Automatics all the way here too. I'm done rowing my rigs around town and in the backcountry. I am even changing my bike to a new Africa twin with DCT.

 

[ExplorerTom]

Nice Jeep.

What 4x4 shop do you use?

 

[MTSN]

Nice Jeep.

What 4x4 shop do you use?

Thanks Tom! I use High Country 4x4 off Sante Fe and Hampden. I've been going there for 15 years, and I highly recommend them. Tim (on this board too) and Chris are the guys I usually work with over there, and they are stand up guys who will treat you right!

 

[MTSN]

Automatics all the way here too. I'm done rowing my rigs around town and in the backcountry. I am even changing my bike to a new Africa twin with DCT.

I can't wait to see that bike in person - it is going to be sweet! I'm thinking about putting a Rekluse clutch in my trail bike to be able to get more technical too.

 

[kojackJKU]

is technical another term for lazy? because that's why I am getting the DCT...ha ha!

 

[MTSN]

I've had a couple of weeks with the 37" KO2s, and I have to say I am extremely happy with the change. My wife drove it last week, and she the ride and steering was better compared with the Duratracs. My bro in law drove it back to Denver yesterday from the trail we ran, and he though it drove much better with more power than their 3.8 liter JKU auto with 285/70/17 Duratracs (don't know the axle ratio). I ran a full tank through it which was 95% city driving, and my mpg was 14.6 which is about 1 mpg less than before. My thought is the mpg hit would be less noticeable if I drove more freeway, so I'll have to wait for a long trip to test that out (it takes me over 2 weeks to go through a tank of gas since I live close to work and have other means to get around).

Here are a couple of pics from the shakedown run with the new tires. The sliders and pinch seam were trimmed which was definitely necessary, and I had the AEV 4.5" lift rear bump stops added. I wonder if the latter was necessary, as it appears I probably have enough clearance to let them compress another .5-1". At least I know for a fact I won't have clearance issues and don't have to worry about going off road. This trail had some snow, ice, mud, rocks, steep climbs and descents and some rocks to flex on. I thought the tires did very well in all conditions, and they held the grip pretty well on a steep descent that was covered in ice where an XJ wasn't so lucky. Still trying to figure out what the story was, but one guy on the trail said he though it was a stolen vehicle.

Of course it doesn't look steep in the photo, but it was steep and slippery enough right here that it was hard to get in and out of the Jeep:

Wrecked XJ:

Testing flex:

Rear clearance (maybe longer bump stop wasn't needed?):

Front droop:

Front clearance:

Testing flex on a rock:

Little higher:

Getting a little air under the tire:

 

[Tombstone17]

Nice! real nice.........Looks like you have come up with a great comb.......

 

[MTSN]

Thank you! I'm quite pleased with how it has come together. It's fun when things actually work the way I hope they will

 

[kojackJKU]

Looks fantastic. The lift and tires are more than I would ever need, but damn it looks sooooo good!

 

[jjohnson1892]

Jeep looks great and I'm in mad envy of the areas you get to check out!!

Just curious, how is that Terraflex rear carrier treating you? Have an ACE bumper and considering switching to the same setup that you have, but am a bit hesitant.

 

[MTSN]

Just curious, how is that Terraflex rear carrier treating you? Have an ACE bumper and considering switching to the same setup that you have, but am a bit hesitant.

I wanted to install the AEV rear carrier with the stock bumper, but the shop recommended I try the Teraflex setup. I have been extremely happy with the choice as it is more than capable of holding the 37" KO2 with plenty of capacity to spare. The best part about it though is how tight and low against the body it keeps the tire. It hasn't blocked my rear view nearly as much as virtually any of the any other carriers I've seen including the AEV one which basically makes the rear window useless.