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another JK question, sand dunes related

3K views 23 replies 16 participants last post by  swampjeep 
#1 ·
for those of you driving relatively stock JK's on the sand dunes

how do they do?

1) what year do you have?

2) is it a rubi or not?

3) are you using low or high range climbing hills?

My reason for asking is this, I'm looking to buy one, and I'm in the air on buying new or used, and rubi or not.

Looking at prices of new to a couple years old, looks like I'd get a brand new Rubi for close to the same price as a couple year old used one.

My problem with that is this: the TJ rubi did not do as well as a non rubi in the sand, high range wasn't always enough to climb hills, and low range was too low.

Is the new motor (introduced in 2012) enough to power the JK up all the hills, even on the super soft sand days, in high range?

If not then I would guess going into low is too low unless putting bigger tires on, which I don't plan to do for a long time.
 
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#6 ·
My wife's bone stock 2008 Unlimited "X" was fine at the dunes - disable traction control, 12psi all around, mash the gas and go (ours was an auto). Even with the anemic 3.8L minivan engine it worked just fine, although you need to get used to the longer wheel base and lower stance. 4Lo helped keep the revs up, which would not be as useful in a rubicon, 4:1 is overkill for the dunes, but it ran OK in 4Hi too.
 
#10 ·
Besides the engine change in 2012, the automatic transmission changed as well. This can make a big difference which range you are running.

2007-11 autos were the old Dodge 42RE, with a 2.84 first, the 12+ use a 3.59 first gear in the 5 speed. Older Jeep 3 speed 32REs were a 2.74 first gear.

So, say a rubicon with 4.10 gears, and the 3.59 first gear, that is the same gearing as a 09 JK with 5.18 gears, or a 3 speed TJ with 5.38 gears, when considering first gear engine speeds. Also remember, compared to earlier motors, the 3.6 has a 6500 rpm redline, so you can hold that gear longer up the hill.

We have the 3.6/5 speed auto in our 12 Durango... its a little soft in the low rpms for such a big vehicle, but shines on higher rpm range, would probably do pretty good in the dunes.

In my F150, we don't use low range. My first gear is 4.17, and axles are 3.55s with 32" tires. Works just about perfect for climbing test hill. We get up to redline but don't shift, and have never had any issues climbing anything there. Its a V8, but also 6500lbs loaded with all the family and gear.

So, thats 4.17 x 3.55 = 14.8 total gearing, with 32s, and 310 hp
The 2012+ JK Rubi = 3.59 x 4.10 = 14.7 total gearing with 31s, so about identical, with about 280hp, and 1000 lbs less weight.


Just providing the nerd perspective..
 
#11 ·
you guys are giving me a pretty good feeling about going with a 2013 Rubi...

I guess I better go price it out at the dealer, but online I see a Rubi for the same as the Sahara I priced out... add my discount and I should be pretty good.
 
#13 ·
I have a 2011 JKU Rubi, the last year of the 3.8 minivan engine and old Auto tranny. I knew that the 4.0:1 low range was too low for the dunes, but would work great at R&V etc. So I put in a RubiCrawler from the start, this gave me the choice of 2.72:1 low range for sand. I run 37" tall tires with the stock 4:10 axle gearing, perfect for the 3.8 to stay in the higher RPM range where it makes a little bit of torque.

Personnally, if/when I buy another I'd get a new one with the Pentastar and 5-speed instead. Unless they ever come out with a diesel in a Wrangler. Because even with the stock tires it cannot hold OD at 70mph unless going downhill, too tall of a ratio for the engine.
 
#22 ·
I have an '09 Rubi. I usually like running the dunes in 4hi but with the auto i can get away with 4lo, too. The big problem is the stock tires. being narrow and the MT tread they really dig when the sand gets choppy. A wider or less aggressive tire would work better. Other than that, no complaints. The suspension handles much better than my TJ did.
 
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