Slip Yoke Eliminator

Hi Matt, Our forest are protected, except for some of the Indian reservations that allow us to travel their trails. If I leave San Diego County, there are some fun rocks in the desert:

God Bless America, ßill O|||||||Omailto: snipped-for-privacy@aol.com Matt Macchiarolo wrote:>

A tail pipe will help....

My old tenant had that same 'muffler' and it roared when he broke the tail pipe. It was mellow with one.

I have a nice sound with my Dynomax super turbo muffler.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

travis wrote:

I think it's time to take your vicodin.

• * * Matt Macchiarolo
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On Fri, 31 Oct 2003 16:06:55 -0500, Mike Romain shared the following:

But there isn't any way to attach a tail-pipe to it because of it's location...

I may wind up going with turbo mufflers.

-- Travis

meek shall inherit the earth. After I'm finished with it.:wq!

Let's just conclude that after nearly 20 years on the road and trail the NP231 & NP242 xfer cases have held up every bit as well as the old gear-driven boxes, and have required far fewer repairs. Why, Hell, even Real Jeeps snap off the output shafts on Spice 18s, D20s and D300s, that's why AA and others sell beef-up kits. Me, I got an Atlas II in the YJ and a leaky

2:1 D20 in the CJ, plus a low mileage NP231 with a Currie SYE kit in a box, ready to sell.

I refer to numerous 4x4 mag articles on the larger output shaft kits now available for all of the gear-driven xfer cases. In particular, the D300 fails with regularity behind large tires, lockers, etc.

Ok, a show of hands: Who in this group has broken the output shaft on an NP231?

Hey Bill!

Allow me to help Gerald. Bill here is the link that you requested. Now go take your Geratol and accept the fact the 231 is just as good as a 300.

Daren

Hi Bill.

Let me show you anther one. This is a quote take directly from the site that I have provided this link to. " The Dana 300 is really quite a strong case. Its Achilles heel is the 27 spline output shaft, which has been known to break off in extreme applications. We can build a 300 with a 32 spline output shaft. The parts and kit are also available separately."

Please note that the info above is a direct quote from the following site.

Daren

How about one from JP Magazine. Will that be valid enough?

Daren

OK Bill,

Just one more. How about 4Wheeler?

Daren

.....I'm not getting in the middle of this! ;-) (Who started this, anyway?)

Unfortunately "Real Jeeps" have Spicer 18s!

I like the final enhancement.

Jeep NP231 "Enhanced"

The NP231 is the transfer case supplied from the factory in all Jeep Wranglers (Except the "Rubicon" edition. While these transfer cases are extremely reliable in an unmodified or near stock Jeep, as the vehicle becomes more radical, short comings begin to develop. There are three primary areas that are addresses. Gear ratio, output shaft problems and chain durability. The advantage of upgrading an NP231 or purchasing an upgraded NP231 for your Jeep is that it is a direct bolt in.

Note: When extensive upgrades are considered the costs begin to stack up. It is frequently more "bang for the buck" to upgrade to an Atlas Tcase or Install a Klune-V Extreme Underdrive

Slip Yoke Eliminator

These cases almost always come from the factory with a slip-yoke output. As the suspension in the jeep moves up and down, the driveline needs to become shorter and longer to accomodate this. The low cost way to do this is to use a "slip yoke" on the rear of the transfer case. This slip yoke works fine when driveline angles are minimal: The pressure on the slip yoke is more or less straight in and out. However, when driveline angles exceed stock, the slip yoke tries to operate at an angle: When the rear axle bumps up going over a bump, the force pushing on the slip yoke is at an angle, and tends to bind. This frequently causes the transfer case housing to crack. Any time a driveline gets much of any angle on it, you want to get rid of that slip yoke. It saved the factory a few bucks, but is no good for us. (you will also need to modify or change the driveshaft to a unit that has a slip joint in it: That length change when the axle goes up and down has gotta go somewhere!)

Note: It is also better to upgrade to a 32 spline output shaft when doing slip yoke conversion. The factory 27 spline shaft will work, but is marginal in strength. High Impact always uses 32 spline mainshaft when doing this conversion.

4:1 Ratio Gearset

This is a relatively low cost way to improve rock crawling gearing performance. Pros and cons of conversion to a 4:1 gearset in an NP231 are covered in the article "A systems approach to 4WD gearing"

Upgrade To HD Chain

Power to the front axle is transmitted to the front driveshaft via a chain inside the transfer case. This chain is adequate and reliable in stock or near stock applications. When we increase tire, engine power or gearing, we begin to stress this stock chain beyond reliable parameters. It is possible to replace the chain and its sprockets with larger components. High Impact offers this upgrade both as a kit and included in complete custom NP231 transfer cases

Dana 300 T-Case Conversions

Actually, when I had them mine looked a lot better than these. Mine did have the inspection hole in the case, either. Fear not, I now have "Real Jeep"-type gear driven transfer cases in all Jeeps...except for the one in the Grand Cherokee....but that's not a Real Jeep....so it must be ok.