Project Cherokee: JB Conversions SYE Installation

JB Conversions slip yolk eliminator
JB Conversions slip yolk eliminator

After the installation of the OME lift kit, I had minor vibrations between 35-45 miles per hour. I heard a lot of bad things about the transfer case lowering kits, so I decided against that as an option to fix the problem. I had already known that the best fix for this problem was to go with a slip yoke eliminator or SYE for short.

What is a slip yoke elimator and why does it fix drive line angles? I will attempt to answer this, but this isn’t my specialty. Pretty much what it does is makes the tail shaft section of the NP231 transfer case smaller, which means that you need a longer driveshaft. This lessens the working angle of the u-joints. The vibration that you feel is the u-joints binding and releasing. A SYE makes the tailshaft of the 231 a fixed output, which means that the driveshaft doesn’t push in and out of the transfer case. You may be thinking, “What happens when the Jeep goes over a bump then if the driveshaft can’t push back into thansfer case?” This is where a CV-style drive shaft comes into place.

Denny's CV-style shaft.

Denny’s CV-style shaft.

The CV-Style shaft has a built-in compression fitting. This will allow the shaft to compress and expand with the suspension, rather than sliding in and out of the transfer case.

So now you see how the two of these pieces together take care of the vibration problem that most vehicles get when a suspension lift is put into place. Now, why did I pick the JB Conversions SYE? I picked it based on quality and price. I posted many messages around the Jeep-L and the forums to see what other people were using and what they though. Most people said that the JB Conversions and the Advanced Adapters kit were virtually identical and used many interchangable parts. If this truely is the case, then I can’t see paying almost $100 more for the AA kit.

Why did I pick Denny’s Driveshafts to make me a CV-style shaft? I picked them based on reputation and quality as well as price. His prices were very similar to Tom Woods, but Denny is right here in Buffalo, so I wouldn’t have to pay shipping. Denny also has a heck of a warranty, If you can twist it or break a weld, he will replace it free. Denny is very well known in the racing and muscle car scene. His shop walls are covered in magazine articles that feature his shafts. His contact info:

1189 Military Road
Kenmore, New York 14217

The Install: I decided to have a performance shop here in Buffalo install the SYE kit. Overall, I think I could have handled it, but being that this is my daily driver, I couldn’t really afford to be without it. So I figured it made more sense to have someone else handle the install. I took it to the shop to have them take the measurements of the new CV-style shaft. Most CV-style shafts need to be custom made to fit the given application. Since Denny was swamped with all the race shafts, it would take about a week for him to get to mine. I didn’t really have a problem since the vibration was minor.

Slip Yoke Eliminator installed.

Slip Yoke Eliminator installed.

About a week later, the shaft was done. I took it to the shop to have them perform the install. It took a little over a day since the shop was somewhat busy. After the install, no more vibrations. The truck is as smooth as the day I took it off the dealer’s lot. (Click picture to enlarge.)

Part of the smoothness is due to the Old Man Emu lift kit. Having heard nothing but good stuff about this brand is what made me go with it. To read more about my Old Man Emu lift kit, please click here.

Vendor Links:
JB Conversions
Denny’s Drive Shafts