Rubicrawler

[haven]

Check out the Advanced Adapters Rubicrawler. It's a new product that should reach the market this summer.

http://www.rubicrawler.com

Advanced Adapters noticed that there's a lot of empty space in the tail housing of the 42RLE four speed automatic transmission used in 4x4 Jeep TJ and JK Wranglers. So they developed a two-speed reduction gear to fit in the empty space.

Result: 4 gears in the transmission * 2 speeds in the reduction gear * 2 speeds in the transfer case = 16 forward gears. The Advanced Adapters web site says they achieve a 108 to 1 crawl ratio using a JK with stock (non-Rubicon) transfer case.

Leaving the transfer case disengaged, you get four new low gears in 2WD that work great for mild off-road driving (or doing burnouts at the drive-in, I suppose).

Because the reduction gear fits inside the transmission, you don't need to buy new driveshafts or fabricate a new frame cross member to remount the transfer case.

Chip Haven

 

[RedRocker]

Damn Chip, I was perfectly happy with what I have till you posted this.

 

[nwoods]

Damn Chip, I was perfectly happy with what I have till you posted this.

LOL, I was just thinking that.

 

[computeruser]

If I wasn't still stuck in the 3-speed world, I'd be so all over that.

 

[haven]

The Rubicrawler will fit 2003-2010 Jeeps wit the 42RLE automatic transmission. Advance Adapters has lowered the price by $100 to $1495 to attract sales.

http://advanceadapters.com/product/4341/RubiCrawler.html

Because the Rubicrawler fits between the stock transmission and the stock transfer case, you can use its 2.72 to 1 gear reduction with rear wheel drive as well as 4x4.

The current Xtreme 4x4 TV project JK uses a Rubicrawler.

 

[JIMBO]

:sombrero: Thats quite a good engineered piece of gear-but

My '08 JKU Rubi with the stock 42rle and rocktrac xfer case can climb trees in 4lo and raps about 3000rpm at 3mph--now

The only reason I could see for the Rubicrawlers use, would be the 2WD low ratio ability and I'm not to sure about that-but

I imagine that any (non-rubi) jk would really benefit from this Rubicrawler use and the price is REALLY attractive--

:costumed-smiley-007:bike_rider: JIMBO

 

[haven]

Agreed. The Rubicrawler is mostly useful if

-- you didn't buy a Rubicon model, and want its lower gears, or

-- you plan to install considerably taller tires, and you don't want to re-gear the differentials. Installing the Rubicrawler is a simple bolt-in process that can easily be switched back to stock form.

 

[JIMBO]

:sombrero: I've seen this advertised elsewhere and I-

Agreed. The Rubicrawler is mostly useful if

-- you didn't buy a Rubicon model, and want its lower gears, or

-- you plan to install considerably taller tires, and you don't want to re-gear the differentials. Installing the Rubicrawler is a simple bolt-in process that can easily be switched back to stock form.

Can't believe that JK/JKU Sahara-X-Sport owners aren't just FLOCKING to purchase this unit--what an off-road miraccle that thing is-

:costumed-smiley-007:wings: JIMBO

 

[Bennyhana]

If I remember, Ian on extreme 4x4 said by putting the rubi-crawler on a rubicon would net like a 10-1 low ratio...

 

[Lumberjack]

:sombrero: Thats quite a good engineered piece of gear-but

My '08 JKU Rubi with the stock 42rle and rocktrac xfer case can climb trees in 4lo and raps about 3000rpm at 3mph--now

The only reason I could see for the Rubicrawlers use, would be the 2WD low ratio ability and I'm not to sure about that-but

JIMBO

Actually I find that the 4:1 is a little to low for some types of wheelin. When in Moab or on the Rubicon, 4:1 is great, but when I wheel Colorado and the back rodes out of Reno and the Sierra's, I find 4:1 to low. Having 2:72 as an option would be great, not such a deep low would be great for scenic wheelin.

Then you also have super deep 2:72 + 4:11 for those rare cases when extreme finesse is required. Watched a Toyota with a doubler on Widowmaker in Moab ease up on the obstacle you could watch to tread blocks searching for traction one at a time, he wiggled across the face 2-3 times and finally found the traction and popped right up it. My 4:1 was not low enough to try that as I still needed go pedal to keep the engine alive.

I am actually trading out my 4:1 next weekend for a standard ratio, will suit the kind of wheelin I am currently doing better...

Its all about options, only problem I have seen on the trails is knowing which gear to use, so many choices and if you use too low of a gear downhill can lead to scary circumstances, watched an old FJ almost endo on Wipeout Hill because of way to low of a gear, he was bounced the engine off the rev limiter to keep from doing a forward somersault, he definitely needed a change of shorts once he got the seat cushion pulled out :sombrero:

 

[haven]

Here's the final drive calculation for the stock Rubicon with manual transmission

first gear manual trans 4.46
Transfer Case low range 4.0
Axle ratio 4.10
Final crawl ratio 73.14 to one

Now look at the ratio you get using an automatic Sahara or Sport model plus the RubiCrawler

first gear automatic 2.84
Rubicrawler 2.72
Transfer case low range 2.72
Axle ratio 3.21
final ratio 67.45

That's pretty close to the Rubicon's crawl ratio for only $1500. However, if you also add bigger wheels and tires, you'll have to add stronger axles. Then add bumpers and a winch, flat-top fenders, a heat extraction hood, the list is as long as your wallet is deep.

 

[bluejeep]

I have a Klune underdrive (David model with 4/1), so basically the same setup as the rubicon with the new box. It's all that the previous posters say.

nice to have 3 low ranges (2.7 / 1, 4/1 , combined insane low ratio > 10/1)
Takes a bit of time to learn what range and gear combo works where

the low low is sooooooo nice for the real technical stuff. Helps keep the breakage down as well

 

[Lumberjack]

Here's the final drive calculation for the stock Rubicon with manual transmission

first gear manual trans 4.46
Transfer Case low range 4.0
Axle ratio 4.10
Final crawl ratio 73.14 to one

Now look at the ratio you get using an automatic Sahara or Sport model plus the RubiCrawler

first gear automatic 2.84
Rubicrawler 2.72
Transfer case low range 2.72
Axle ratio 3.21
final ratio 67.45

That's pretty close to the Rubicon's crawl ratio for only $1500. However, if you also add bigger wheels and tires, you'll have to add stronger axles. Then add bumpers and a winch, flat-top fenders, a heat extraction hood, the list is as long as your wallet is deep.

I thought the Rubicrawler was going to be available in both 4:1 or 2.72:1?

 

[jeepdreamer]

And...Yeah.

I was wondering when someone was going to mention the Klune. Its been around a while and never got the love it deserved. Basically the front end of a 4sp Atlas...Not sure if it was an "in conjunction with" kind of deal or what but it works! I just can't get them to answer an email...Grr!
There are alos other options out there for crawlboxes...
Box4Rocks
Rooster
BlackBox...
All of them (including the Rubi) operate off the same concept...using the planatary drive off the NP 2 series t-cases. The lighter ones usually run the 3 Pgear assemblies while the HD units run the6 gear ones...

 

[Root Moose]

FWIW, the AW4 torque multiplication rule of thumb is 1.7-1.8.