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-   -   Rubi 4:1 transfer case (http://www.wranglerforum.com/f274/rubi-4-1-transfer-case-248191.html)

CMunlimited 06-09-2013 11:51 AM

Rubi 4:1 transfer case
 
I've been reading up a lot on the technical aspects of offroading but can't seem to wrap my head around the pros/cons of having the 4:1 transfer case. So for those experienced, can you run me through the PHYSICAL effects of shifting into 4LO (and thus utilizing the 4:1 ratio)?
1) Automatic: after shifting into 4LO, what physically happens? ie. so you're going 2-3 mph while shifting, does the Rubi maintain that speed without getting on the gas? Does it maintain a certain speed even while not getting on the gas?
2) Manual: same as auto?
3) vs. a lower ratio t-case: what are the physical effects?

Thanks!

Rogerg 06-09-2013 12:07 PM

The 4.1 TC is one feature I like about Rubicon other than the d44 front and lockers.

When in 4lo and say your climbing over an obstacle/rock you basically crawl up or down on it. Without it you constantly have to play with the gas and brake since you obviously don't want to come down too fast.

Its almost like wheeling with your foot on the gas and brakes at the same time. Im terrible at explaining things but if you know how slow your Jeep is in 4lo in 1st gear quadruple the slowness. Thats what 4.1 TC would be.

nwbronco 06-09-2013 12:30 PM

Everyone understands the from a stop feel. The engine and transmission are working together to propel the vehicle forward. The lower 1st gear does that. Now, multiply that times 4. You now have the ability to 'propel' your rig over an obstacle. It will move at the touch of the throttle now. And with lockers engaged, that power is delivered to all 4 wheels. There is no momentum needed now. The rig will provide the power to get over the obstacle with ease. It is truly hard to explain it. You really need to test drive one or ride in a rig set up this way. I know that the Rubis running with us tend to get bored. They just put it 4Lo, lock the axles and drive. No challenge.

Once you find out the capabilities, you'll want to test those. Be careful. It is a Machine with a specific design. That's why top speed is 4Lo is close to 20MPH. And when the axles are locked. The rig will try to push you straight through tight turns.
Bob K.

Flint_Holbrook 06-09-2013 12:39 PM

When off road your goal is to go as slow as possible and as fast as necessary. The low gears help the the "slow as possible" part. In my CJ I run 6.32:1 low gear transmission, 4:1 Klune V, a 2.72:1 Dana 300 T-case and 4.56:1 axle ratio. In low low this turns out to be 300:1 final drive ratio. This allow super control and prevents drive train damage even though the torque of the motor is multiplied.

In my JK Rubicon the 4:1 case multiplied by the 4.1:1 axle ratio, times the low ear in the automatic. I think the auto has a 4:1 or a 3.6: low gear which makes the final low drive gear between 60:1 and 66:1 depending on the auto first gear. This is still very god and provides much control but also enough speed when needed.

Physically...it is slow

jadmt 06-09-2013 12:41 PM

think of a mountain bike. dropping into 4Lo is like dropping on to the small chain ring in front and the largest in back. It allows you to inch slowly forward with each pedal stroke compared to be being on the large chain ring in front and the smallest in the rear where each pedal stroke propels you further but takes more power to do the same pedal stroke.

CMunlimited 06-09-2013 01:06 PM

Whew, glad you guys understood my question! So I can picture it in auto...for manual, which is what I'm planning to get, is it the same? Does it mean you can just sit in 2nd or 3rd and crawl, without constant feathering of the clutch?

And vs a Sahara t-case, the Rubi will crawl slower then?

Rogerg 06-09-2013 01:13 PM

To get the best of the 4.1 ratio you have to be in 4lo 1st gear auto or manual. My Rubi TJ is a manual so when im out crawling in 1st gear I never have to use the clutch until im in full stop.

Only Rubi has a 4.1 TC from the factory.So ya they will be slower.

Quote:

Originally Posted by CMunlimited (Post 3841996)
Whew, glad you guys understood my question! So I can picture it in auto...for manual, which is what I'm planning to get, is it the same? Does it mean you can just sit in 2nd or 3rd and crawl, without constant feathering of the clutch?

And vs a Sahara t-case, the Rubi will crawl slower then?


jkjeeper06 06-09-2013 01:15 PM

Quote:

Originally Posted by CMunlimited (Post 3841996)
Whew, glad you guys understood my question! So I can picture it in auto...for manual, which is what I'm planning to get, is it the same? Does it mean you can just sit in 2nd or 3rd and crawl, without constant feathering of the clutch?

And vs a Sahara t-case, the Rubi will crawl slower then?

Yeah. The clutch never needs to be feathered with 4 low that's why most manual owners use 4 low any time they are off road. It takes all the wear off the clutch. You don't even need to slip the clutch to get going. You can really just dump the clutch on a hill with no gas and it won't stall or try to stall. It'll just go. So when I wheel I generally just use gears 1-3 on my manual and that gives me the ability to crawl 1-10mph(I have the sport not rubi)

The difference between sport/sahara and rubi transfer cases Is the ratio. It's 2.72 in the sport and Sahara in addition to the 3.21 or 3.73 rear end of the sport and rubi. So depending on the rear end ratios you are comparing, the rubi will crawl between 50 and 93% slower than a sport/Sahara (3.73 vs3.73 and 3.21vs 4.1 respectively, both combined with respective transfer cases)

jadmt 06-09-2013 01:29 PM

I have been toying with installing a rubi transfer case on my sport with 3.21's. Apparently lots of guys that do the 5.7 and 6.4 conversions prefer the the 2.72 transfer case so just need to find a convert that has a 12-13 automatic. The transfer case in the automatic 2012 and 2013's is different then the earlier ones and the manuals. Seems like the best of both worlds that way.

Hokieneer 06-09-2013 02:01 PM

Just for some real world numbers in the rubi in 1st in 4L at 3000 rpms the jeep is moving 2-3 mph, in 3rd at about 1200-1300 rpm I may be doing 5-6 mph. it feels extremely touchy in first you need little if any throttle input to do a lot of stuff. However when dealing with deep mud it can feel a little slow but proper gear selection is important here. Another word of advice is do not press in the clutch when moving it can over rev the clutch and the clutch can come apart

sinbob 06-09-2013 02:31 PM

To give u an idea of what a Rubi can do and the differences between a stock jeep and the rubi.....here is a real world situation

Back in March I went on a run to blue canyon with some friends. they all wanted to go to the gravel pit there...I didn't, so I took off on this old fire trail I knew. There was a kid in a stock wrangler sport and another in a built up Toyota who followed me.
we got to one obstical and I turned around to make sure they got thru. we started up the ridge through heavy brush. They got stuck. There was a break in the brush on my left so I locked up and went around them. Winched the Jeep up and told him to floor it and don't stop till he got to the top. When he got back to help with the toy, he was really jazzed that he had actually made it. Winched the toy up but he couldn't go any further. The hill was too steep for his carbureted truck. So I turned around, ran the winch cable under the jeep, hooked up to him and pulled him up the hill to the top. No gas no spinning tires just crawled. The kid with the other jeep was astonished:eek:
You went up this hill, towing him, with out even trying....very humbly I said 'yeah she does ok':rofl:

Now that is what a rubi can do, or any other rig set up the same way!!!!!:dance:

With the 4-1 rubi xfer I believe u almost have to be stopped to engage as it is gear driven....no chain like the other one.

SilverSport 06-09-2013 05:25 PM

Rubi 4:1 transfer case is chain driven.

sinbob 06-09-2013 05:34 PM

Quote:

Originally Posted by SilverSport (Post 3842649)
Rubi 4:1 transfer case is chain driven.

Your right:thumb: I stand corrected:dance:

http://ts2.mm.bing.net/th?id=H.48298...h=181&c=7&rs=1

SilverSport 06-09-2013 07:00 PM

Quote:

Originally Posted by sinbob (Post 3842685)
Your right:thumb: I stand corrected:dance:

http://ts2.mm.bing.net/th?id=H.48298...h=181&c=7&rs=1

That's how I knew. I had seen a parts breakdown like the one you posted. LOL

live_slow 06-09-2013 07:17 PM

The shifting into 4L on the MT Rubicon is a little wonky the first couple of times.

I have to be rolling or it don't want to go. (As it says in the manual 2-3 mph, or barely rolling.)

But as others have said, it's pretty much easy mode. The built guys running crawl boxes can attest to the advantages of their extreme crawl ratios. But the Rubicon set up is very sweet as it is. Very little fanfare involved.

tae73 06-10-2013 08:58 AM

Also in 4lo with a manual you do not have to engage the clutch to start the jeep. Just be ready for it start moving!


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