Installing a Slip Yoke Eliminator SYE in a NP231

Slip Yoke Eliminator Installation
Well written instructions came with the kit

First I removed the transfer case from the transmission. This was pretty easy since they were both laying on my shop floor. I did have to jack up the transfer case to get to the bottom bolt. That seems a bit backwards as the top bolts are the hard one to get to with it installed in the Jeep.

Next I used my pressure washer to remove most of the dirt and grease form the outside of the case. There was all colors of mud. I am sure there was some from Harlan, Aetna Mountain and Golden Mountain as well as some other places still on there.

sye install NP231
NP231 transfer case ready for SYE install

Next, per the directions, I placed the transfer case in 4 Low. Next I used a 1 1/8 socket on my air wrench to remove the nut on the front yoke and then removed the front yoke.

Front yoke removed
Front yoke removed

Next, using a 9/16 wrench I removed the selector lever. If I had not moved it to 4 low before removing, turning the nut would have shifted it there any way.

SYE install np231
Shift lever removed

Next I removed the three 15 mm bolts that held the tail housing in place and tapped the tali housing off. This gave access to the snap ring that holds the main shaft to the rear bearing.

tail cone off
Removing the tail cone exposes the snap ring.

With that snap ring off, I removed the 10mm bolts that hold the output housing in place and tapped it off. The speedometer drive had been previously removed.

Output housing removed exposing the oil pump
Output housing removed exposing the oil pump
Stock 231 output housing
Stock 231 output housing

Next I noted the locations of the three different types of fasteners that hold the two case halves together. All but one has a 15 mm head. Two of these have washers and go over the alignment dowels. For some strange reason there is one bolt that has a 10mm 12 pt head and is longer than the rest. It is on the top.

ready to seperate case halves
Note the location of the three different types of fasteners.

With all the bolts out, I used a flat blade screw driver to pry the case apart using the pry slots. I was careful not to pry anywhere else so I would not scratch the sealing surfaces.

At this point, some more fluid came out even though I had drained it earlier. I carefully separated the oil pump from the pick up tube and removed it.

After removing the rear case half, I inspected the chain and the magnet. Even though this Jeep shows over 220,000 miles on the odometer, the chain looked great and there was very little metal on the magnet.

Rear case off
View inside the NP231 with the rear case off

Next I pushed the front output shaft out and removed it with the chain. I inspected both the sprockets and the chain further. Still no visible wear.

Front output shaft and chain
Front output shaft and chain

Next I removed the main shaft from the case. I photographed the shaft so I would know the relationship of the mode selector and drive gear.

Main shaft
Main shaft with mode hub and drive sprocket

The snap ring was just a hair too big for my Craftsman snap ring pliers to open. So I modified the pliers by grinding off the stops just a bit so they would open wider. The snap ring then slid off easily. I was then able to slip off the mode hub and sprocket.

This being an early 231, I had to remove the caged bearing from the sprocket before I could reuse it on the new shaft. I used my ball joint press to press out the two bearings.

pressing out the roller bearings
pressing out the roller bearings

I pre lubed the new shaft and slid the sprocket in place and then the mode hub. I installed the new snap ring from the kit.

Next, I slipped the new main shaft into position in the case. I then removed the old spline seal form the front input shaft and installed it with the chain. I decided to wait until the front yoke is ready to go on to install the new spline seal.

New main shaft in place
New main shaft in place

I then test fit the rear case half to see if the shift rail needed to be modified. Sure enough this is one of the ones that required the rail to be cut as it extends 1/2 inch too far.

shift rail too long
Need to cut 1/2 inch off the shift rail.

I reinstalled the shift lever and moved the case through all its positions to see how the shift rail moved and saw that it only interfered in 4 low. I cut the extra shaft length with a cut off wheel on my grinder after marking the spot with tape.

Cutting the shift rail
Cutting the shift rail

I also inspected the oil pump and saw the pump housing seal was worn and needed to be replaced. I got a new one from Crown along with the proper RTV to seal the case.

New oil pump seal
New oil pump seal

After a final inspection, I applied a bead of RTV to the case and after letting it cure I put the two case halves together.

RTV curing onthe rear case half
RTV curing onthe rear case half

Here is where I hit my first snag of the installation. The oil pump needs to be installed at the same time as the rear case so that the pickup up tube can be inserted into the pump. On a stock transfer case, you can slip the pup off the drive gear and get enough wiggle room to install the tube after the case halves are together. However, on the SYE shaft, the rear section of the shaft is bigger and stronger making it very hard to get enough room to move the oil pump.

There was a bur on the output splines that the oil pump has to slide across and working by myself, I could not hold the case steady and guide the pump down the sticky splines. I went ahead and assembled the case halves, thinking I could install the dip tube later as I always have on stock cases.

I had already torqued the case bolts to 25 ft lbs before I realized I was not able to move the pump like I was accustomed to. However, with some fishing with a dental pick and a small screwdriver, I was able to install the pick up tube and eventually get it seated in the pump. Next time I will get help if necessary to make sure the oil pump and case go together as a unit.

Oil pump in place
Oil pump in place

Next I placed one of the snap rings for the speedometer drive gear on the shaft, then slipped on the blue drive gear followed by the other snap ring.

Speedometer drive gear in place
Speedometer drive gear in place

Next I applied a bead of RTV to the new output housing. The Crown Kit comes with eh bearing and seal preassembled in the new housing. I torqued the bolts to 17 ft lbs.

New Output Housing
New Output Housing

The output housing is drilled an tapped for a vacuum switch on the shift rail. However, the Jeep this case is going into does not use one and this kit comes with a handy plug. I noticed before screwing in the plug that the shit rail looked very close to the end of the hole. Sure enough on a test fit, the plug hit the end of the rail about one thread form being tight. I shifted the case around and found that if the plug was all the way in, the case would not fully shift into 4 Low.

I must not have cut the shaft short enough buy 1/16 inch of so. Rather than pull the output housing and cut the shaft again, I simply ground off the end of the plug. I had to remove about on thread to get it to clear.

Shift rail plug
Shift rail plug

Next I installed the two yokes and called it done for now.

Rear yoke installed
Rear yoke installed

I used a spare speedometer drive gear to plug the hole until the case is ready to be installed in Jenny’s Jeep.

Slip Yoke Eliminated!
Slip Yoke Eliminated!

The next step will be to determine the best way to set the pinion angle as the pinion now has to pint at the transfer case instead of being parallel to the out put shaft. Our plan is to use a stock front drive shaft in the rear position.

Overall, I was very pleased with the quality of the Crown Kit and the well written instructions. I am not sure how much time I spent on this project as the time was spread over several days. The new main shaft is much larger than the original in the tail shaft and speedometer drive areas so in addition to being shorter, it also looks much stronger.

Note how much bigger the SYE shaft is than the original
Note how much bigger the SYE shaft is than the original

Update: The case is now installed in Jenny’s XJ. It took approximately 8 degrees of shims to align the pinion with her three inch lift. The shift rail needed to have been cut shorter as the plug will bind the shifting into 4 low if screwed all the way in. I added a second O ring to cure it. Other wise it works great. See the write up for installing the SYE in the Jeep Cherokee here.

Wrenchfest 2010

Wrenchfest in Kentucky

{This article appears in the April 2010 issue of Jeep Action magazine. Photos my Matt Gibson.}

Imagine taking a bone stock Jeep and installing a 4.5 inch lift with taller springs; replacement controls arms, longer shackles and a transfer case drop. Add a custom fabricated bumper and winch mount, front and rear lockers and trimmed fenders for clearance. Now imagine doing all that in one weekend.

That is exactly the transformation that Matt Gibson made to his Jeep in a friend’s backyard garage in Kentucky.

Matt is no stranger to organizing big events as he is the organizing force behind the Kentucky Derby Festival and Thunder Over Louisville. People who only know him from his day job often have no idea how he spends his adventure time.

Matt began by securing an appropriate work space. His friend Neal Hoover offered up a nice two bay workshop equipped with compressed air, a welder and plenty of space to work.

Next, he made the call to his friends on the Yahoo Groups XJlist for some wrenching help. This diverse group has had many off road adventures together and experience working together from many a trail repairs, but they had never done a project like this one. About a dozen members traveled from up to eight hours away to join the fun and help Matt get his rig built.

The main reason that it was possible to build a Jeep so quickly was that Matt already had all the parts he needed except for the front bumper and Winch mount installed on his old faithful XJ Red. Red however was now suffering from severe rust damage and a weakening engine. Rather than continue to patch Red, Matt elected to take over his wife’s white XJ which had just been replaced by a larger SUV.

Both Jeeps in the shop
Before

The transformation began on Friday with the group helping Neal clear his own projects from the shop to make space for the two Jeeps. His custom J truck was moved to a safe place at a neighbor’s house for the weekend and his off road XJ took up watch in the muddy yard after being used to load the J truck on the trailer.

Once the two XJ’s were on jack stands, Evan Purser who traveled form North Carolina began work on removing the front axle as a unit. This would swap the locker, Currie steering, lift springs and control arms with just six bolts or so. So began the good plan violently executed as the control arm bolts were all very rusted. However, as another team set to pulling the front from the white Jeep Evan and his team powered out the rusty bolts and had the axle on the ground and ready for transplant before the mid evening pizza break.

Front axle dropped from red Jeep
Front axle dropped from red Jeep

Mike Strawbridge and his son Scott who drove from Tennessee began work removing the rear axle assembly. The front spring bolt was rusted solid and even cutting into the floor to access the nut did not release it. They finally had to cut the bolt to extract the spring.

On Saturday morning Adam Olukalns, also from Tennessee, began work on fabricating a new bumper and winch mount. After a few mock ups he and Brian Klotz took over the picnic table as a cutting and welding surface and began their art work.

Matt’s brother Mitch brought doughnuts and coffee for the group before he, Neal and Wayne set into wrenching on the rear axle of the white Jeep.

Matt kept the group organized with complete list of tasks to be done on a white board in the shop. He tried getting involved with the wrenching as much as possible but he was always called away for a decision on the Jeep or for other organizational duties.

The list!
The list!

The rear leaf spring bolts on the white Jeep proved just as stubborn as the red Jeep and the floor had to be cut as the nut broke loose in the unibody. Soon however, both rear axle assemblies were on the floor ready to be swapped.

At lunch break Neal took every one next door to see his project custom J Truck. The body was fresh back from the paint shop looked great as the group pushed it out into the sun shine for viewing. Matt’s wife Allison supplied plenty of chili and hot wings for the group to eat and kept the food coming the entire weekend.

One the lifted axles were in place under the white Jeep, Mike and Scott set the red jeep on the stock axle even without the benefit of bolts to hold it in place. They put some spare wheels on it and pushed it out side. This made space to move the bumper fabrication process inside.

Bumper fabrication
Bumper fabrication

Once inside, Adam began giving welding lessons as he practiced his art. Frosty, a local, welded up the rear floor that had been cut and Mike installed the transfer case drop removed from the Red Jeep.

Work Continues on the white Jeep
Work continues on the white Jeep

Having so many people working in close proximity proved the team work of this diverse group who mostly see each other once or twice a year. The only resource that became a scarcity was the 220V outlet that had to be shared between welder and the air compressor. The group quickly worked out how to let the compressor run to fill the storage tank and then swap back to the welder.

Josh Purvis began trimming the fenders for extra clearance after Scott removed the stock fender flares. The result looks better-than-factory

By late Saturday night, most of the list was checked off on the white board. Even his snorkel made the move and was hooked up to the intake.

New front bumper in place
New front bumper in place

Sunday morning, Mike and Scott loaded up the left over Red Jeep parts to be used on other XJlist member Jeeps. In the shop, final details were made to the bumper and trimmed fenders.

The steering was reconnected, seat covers installed and brakes were bled and by early afternoon, Matt was able to drive the Jeep out of the garage. Before the test drive Neal showed the group how to align the front suspension and the Jeep drove perfectly.

Ready for a test drive.
After.

Being able to build an off road ready Jeep in one weekend was made possible by careful planning and having a great group of friends working together to make it happen. Many of the group commented that this weekend working together was one of the most fun times they have had as a group. That says a lot considering the adventures this crew has undertaken over the years. Working as a team to accomplish a goal and seeing the result drive away was very rewarding. Rewarding not only to Matt, but to all those who worked to make it happen.

We all look forward to seeing the new white Jeep on the trail soon.

Some of the folks that made it happen
Some of the folks that made it happen

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Jeep Cherokee Rear Locker Installation Chrysler 8.25

Jeep Cherokee Rear Locker Installation Chrysler 8.25

In order to boost Jenny’s Jeeps off road abilities, I recently installed a Richmond Gear Lock Right locking differential. It is one of the few available for the Chrysler 8.25 that she has in her Jeep Cherokee.

I like the lock right for its simple and strong design. It simply works and works well. I found it surprisingly easy to install as well.

The installation manual that comes with it is very thorough and describes the exact procedure you need to use to install the locker in place of the spider gears. However, it was very confusing to me to read. I was confused because it covers so many different options like if c clip or not, thick gear or not that I got lost skipping from section to section. I think I read the manual about three times before I figured out I could skip three fourths of it.

First I coated my hands with Market America Clearshield.

I began by cleaning the cover and cover bolts of off road mud. I think I saw traces of Harlan, Aetna and Golden Mountain still on there. I used a wire brush to clean the bolt heads.

8.25 locker install Jeep cherokee
Cleaning bolts

With the cover bolts out, I pried off the cover and let the grease drain into a pan. Then I set the cover aside.

Jeep Cherokee Locker install 8.25
Draining the grease

Next I inspected the differential carrier and gears. There was some wear on the pinion from where the nut had backed off a while back but otherwise every thing looked good.

I then removed the bolt that secures the cross shaft. Then I removed the cross shaft and the two spider gears on it. Next I bumped in the axles and removed the C clips and the other two spider gears.

Jeep cherokee 8.25 Spider gears
Old parts out

I removed and inspected the thrust washers. I used some heavy grease to secure them on the appropriate new drive gears.

I then spent some time studying the locker parts and trying to figure out how it actually worked. By the time I had test fit all the pieces in place – making sure it was the right spline count etc.- I had completely assembled the locker. However, I had not installed the pins or springs along the way so I had to find the disassembly instructions and take it back apart to continue with the installation.

Lock Right parts
new lock right parts ready to go in

Next, I coated the parts in axle grease to glue them together. I assembled the concentric springs as described in the instructions and set them aside.

First I set in the ring gear side gears and installed the C clip. Then I set all the pins in place. Next I set the opposite side cog in place. I used a dental pick to fish the C clip into place through the slot in the gear. The instructions talk about making a tool but I did not need it for either installation or removal. The grease on the cogs held them firmly in place while I installed the clip.

8.25 lock rite locker install
New parts in

Next I installed the springs on top of the pins. Then I slid the cross shaft back in to place and tightened the securing bolt.

Lock right locker installation
All done

I was done before I knew it.

I rotated it all around to make sure I had not missed anything. Next I cleaned and replaced the cover. I used Black RTV for a seal. I then filled it with the recommended 85-140 gear oil.

I then took it out to the wide spot in the driveway and did a couple of doughnuts to prove that the rear was in fact locked. See the locker test video here.

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Janice’s Heart Attack

women heart attack symptoms

When Janice asked me to call 911, I knew something was bad wrong. She never gets sick. She never goes to the doctor and she never asks for help. And, we never saw this coming.

It turns out that a woman’s heart attack symptoms are very different from what I learned in my years as a first aid responder. I was always taught to look for tingling in the left arm and pressure in the chest. She did not express any of that.

For a few weeks, she has been complaining of a sore wrist and both arms aching. We thought this was an injury from playing Wii sports. Her pain would usually go away by a simple massage or some tension on the wrist. The methods described on Lori Painter’s Inspire to act blog relieved the pain every time.

She also mentioned some middle back pain. Again this pain was relieved by massage.

I never realized that these were the known heart attack symptoms for women. When the ambulance driver told me she was having a hearty attack, I almost had one myself. It was the last thing I expected to hear.

When he said they were life flighting her to a trauma hospital, I was even more shocked. I realized it must be very serious.

She had already been at the hospital for 17 minutes by the time I got there according to the ER desk. I waited a bit but when I went to check on her, they had lost her int he computer system. Erlanger is a large hospital so it was impossible for me to find her without help.

A friend who works there suggested that she was probably in the Cath lab and told me where to go. I found a very helpful nurse along the way who was intrigued by the unusual name of Strawbridge. She was finally able to find Janice for me.

I got to see her for just a few seconds before she was whisked off to emergency bypass surgery. She had seven blockages that required three bypasses to correct.

I am going to have to learn more about how women present heart attack symptoms to that I will be more aware for the women in my life.

The Spirituality of Driving

The Spirituality of Driving

Special Stage one Rally Tennessee 2005

In his book, The Power of Now, one of the examples Eckhart Tolle uses of people who naturally live in the moment are people who drive race cars. Being in the moment is how he defines a spiritual process.

Having driven in automobile races and rallies, I understand what he is saying. In order to be competitive and to drive safely, you need to have your mind clearly focused on the task at hand when driving a race car. If you are thinking about what you did last week, or what you plan to do after the race, you will loose time on the track and in the worst case, you will crash the car.

I have also found that driving off road makes me focus on the moment almost as much as racing. While the time pressure is not always there in the off road environment, the need to be clearly alert to my surroundings is. I have to know where my tires are at all times and be keenly aware of the amount of traction available. I can’t do any of that if my mind is distracted or focused elsewhere.

Often as we drive our daily commutes, we do not have this keen focus to the task of driving. We sometimes put driving on mental auto pilot and allow our minds to wander through all sorts of thoughts – some that make us happy and others that bring us grief.

We can however choose to use any time behind the wheel as a deeply spiritual time. By simply focusing on driving the car and paying attention to the surroundings, we can bring our focus in to the eternal now and block out thoughts of past and future.

Often it is easier to bring back attention to driving by taking a different route. For example, instead of taking the interstate, take the old US highway that parallels it. It may take a few minutes longer but just notice the feeling of release that you feel as you look at the scenery and focus on the details of driving the car.

Even a familiar road can bring release if you focus on feeling the contact of the wheels to the pavement through the steering wheel. Listen to the sounds of the engine and the whirr of the gears turning making the car go forward.

I like driving my Jeep because it gives me a great feeling of being in contact with the road. A quieter car does not give me this same feeling of connectedness. I also get this feeling form driving sports cars whose stiff suspension keeps me in touch with the road surface.

It is easy to make driving a spiritual experience. Just focus on the things that are happening right now in the moment. Forget about all the things in the past that you are driving away from. Stop worrying about the potential future that may or may not happen when you get there. Just focus your attention to driving the car right now where you are.