!: Jeep Wrangler Rubicon Express SYE Slip Yoke Eliminator Installation

It's now common knowledge that Wrangler owners like to have fun and what's more fun than a bigger Jeep? Not much!

The problem Wrangler owners face when lifting their Jeep is that short rear driveline. Any type of suspension lift that exceeds 3.5" is likely to cause driveline vibrations. Aside from lowering the transfer case (which also lowers ground clearance), the easiest way to eliminate driveline vibrations is to get rid of the short, slip-yoke type driveline and replace it with a longer, CV type. The only way to do that is to replace or modify your existing transfer case.

Replacing the transfer case can cost upwards of a couple thousand dollars. Unfortunately, most of you (like me) probably don't have that kind of money available to spend on a transfer case swap. That leaves us the option of modifying the existing transfer case by removing the tailcone output section and shortening it by about 3". Doing this will allow you to install a driveshaft that is about 3" longer which, in itself, will alleviate driveline angles, but better yet, it will allow you to switch to a CV type drivehsaft which better at handling sharp angles than its slip-yoke counterpart.

Installing a Rubicon Express slip yoke eliminator takes about two hours and requires the following tools.

Basic mechanics wrenches/sockets
Circular saw/grinder with a metal cutting blade (a Sawzall will not work)
Center punch
Hammer
Electric drill
Tap handle - for the 3/8" tap.
Do not use a wrench to turn the tap.
A wrench does not allow you to put equal force on both sides of the tap like a handle does and therefore you can easily break it off inside the shaft.
1/8" and 5/16" drill bit
3/8" and 5/16" Allen wrenches
Cutting oil
RTV silicone sealer
Loctite

The advantages of using this particular kit are simple: it's cheap ($199 USD), easy to install (done while the transfer case is in the vehicle), improves your lifted vehicle's rear driveline angle, and allows a lowered transfer case to be put back into its stock location.

Remove the rear driveshaft from the vehicle.
On the rear axle, this is done by removing four 1/4" bolts and two steel retaining straps from the differential output yoke. At the transfer case, simply pull the driveshaft out of the slip yoke. Some oil may spill from the transfer case when the shaft is removed but not a lot.

Remove the tailcone section from the transfer case.
The tailcone is held to the transfer case by three bolts. Remove them and tailcone should pop/slide off the case/shaft. If not, lightly tap it on the sides with a hammer to nudge it free from the case. The only thing holding it in place at this time is silicone sealant.

Seal the output shaft bearing surface to avoid contact with debris.
Rubicon Express suggested the use of duct tape, however other items such as Reynold's saran wrap will work. Be sure to use a liberal amount so no debris can get into the output bearing when you cut the shaft off.

Measure and mark the shaft so that 1" of splined shaft will remain.
Remember the rule, "Measure twice. Cut once." It may be wise to mark a little more than 1" of shaft because too long is better than too short. If you cut the shaft too long, it can be shortened. If you cut the shaft too short, you'll need a new one. You will need a circular saw with a metal cutting/carbide blade. A sawzall will NOT work. A 4.5" hand grinder is ideal for this because it's small enough to fit in the confined area you'll be working in. When using a grinder, make sure you cut slowly and no more than 30-60 seconds at a time. This will prevent the shaft from getting overheated and warping. After you've cut through the shaft, if it isn't square at the end, grind it down to make it square.

Center punch the end of the shaft.
This will ensure the drill bit starts in the center of the shaft when drilling the pilot hole. To make finding the center of the shaft easier, place the CV Output Flange over the cut-off shaft. This reduces the visible surface area from about 1.25" diameter to 0.5" diameter allowing you to find the center of the shaft easier. Be sure to hit the centerpunch hard enough to put a dent in the end of the shaft deep enough for a 1/8" drill bit to sit in.

Drill the pilot hole in the end of the shaft.
This is done with a 1/8" drill bit. This step is easiest done with the vehicle raised 6" on jack stands and the transfer case lowered 2". With the vehicle being as high as possible, you'll be able to sit under it and gauge the direction of the drill. The pilot hole needs to be drilled into the shaft as straight as possible so take your time. The pilot hole needs to be 1"-1.25" deep. After that is done, you need to bore out the 1/8" pilot hole with a 5/16" drill bit. To be on the safe side, you may want to use a 3/16" bit before going to the 5/16" bit. This makes it a little easier to drill a straight hole. Make sure the final depth of the pilot hole is 1.25".

Use a 3/8" -24 tap to cut threads into the 5/16" pilot hole.
Use cutting oil (or WD40) and keep the tap threads clean. CAUTION: If you have never used a tap before, then tapping the pilot hole is not the time to learn! For best results you should read up on how to correctly do this and then practice on another piece of steel. The proper way to tap a hole is one full turn forward (clockwise) and one-half turn back (counter-clockwise), but since the shaft is made of hardened steel, tap it in one-half turn forward increments. Better safe than sorry at this point.

Install the Oil seal in the Bearing/Seal Flange.
You will need a press, vice, or similar tool to do this. The oil seal needs to be pressed straight in or damage will occur. Afters the Oil Seal is pressed into the Bearing/Seal Flange, turn it over and run a bead of RTV Silicone along a circumference just inside the three bolt holes. The bead should be about 3/16". Allow about 10-20 minutes for the silicone to "skin" over before installing it. Take this time to lube up the rubber part of the seal where it will make contact with the CV Output Flange. Wiping transfer case oil on it with your finger will be adequate. Make sure to put oil all around the black rubber part of the seal. This is to reduce friction otherwise the seal will melt and tear within the first mile of driving.

Install the Bearing/Seal Flange.
Remove the duct tape, saran wrap, or whatever you used to protect the transfer case output bearing (in step 3) from the transfer case output shaft. Clean the surface near the bearing making sure there is no leftover residue from when the tailcone was removed. Use three grade 8 M10 x 25mm bolts to install the Bearing/Seal Flange onto the transfer case. Apply Loctite to the bolts before inserting them. Now would be a good time to apply RTV silicone to the remaining splines of the output shaft. This is to prevent oil from leaking through the CV Output Flange once it's installed.

Install the CV Output Flange.
Slide the CV Output Flange over the output shaft splines and through the oil seal. Take care not to damage the seal. You may need to use a hammer to lightly tap the CV Output Flange down the shaft. Use a 3/8" bolt and washer to bolt the CV Output Flange to the output shaft. Use loctite to hold the bolt in place.