Mike – Page 88 – The Jeep Guru

February 8, 2010September 30, 2014

Jeep Cherokee Transmission replacement

When my friend Jennifer started having trouble with the transmission in her Jeep Cherokee, I was really surprised. The AW4 in the Cherokee is a very reliable transmission. However, hers was becoming very sluggish to engage either drive or reverse when cold. It would work fine once warm but was taking longer and longer to warm up each morning.

Another friend of ours had a transmission available as he was parting out his old off road Jeep. I made the trip to Kentucky to help him swap parts and picked up the left overs. Loading it on the trailer was fun since it had no brakes after the axle swap. But it did prove the transmission worked fine.

The swap began with removing the transmission and transfer case from the donor Jeep. Since both Jeeps had the 231 transfer case I decided to simply swap the transmission and transfer case as a unit.

I began by disconnecting the transmission control and sensor wires at the firewall. There are three connectors. Also the transmission kick down cable needs to be disconnected from the throttle linkage. The battery cable needs to be disconnected at this time as well.

With the Jeep on the lift, I removed the two drive shafts. Then the starter and the inspection plate from the front of the transmission. Next, I unplugged the wires to the oxygen sensor and removed the bolts holding the exhaust to the manifold. I also unbolted the transmission filler tube from the backing plate.

I fabricated a mount for my hydraulic lift table to hold the transmission and transfer case so I could lower it down once it was loose. I cut the exhaust between the muffler and tail pipe to make it easier to handle.

With the transmission supported by my table, I removed he cross member. This is when I discovered that the transmission mount was broken and had been for some time. The transfer case shift linkage was slightly damaged due to the movement, so I left it in place and simply disconnected it from the transfer case. The exhaust came down with the cross member as well.

Next I removed the cooling lines from the side of the transmission. It took quite a while to clear the dirt and mud out of the quick connects to get them to release. I used a dental pick to scrape between the tube and the connector.

Next I removed the four bolts that secure the torque converter to the flex plate. I was surprised at how easy the engine turned over indicating that it was low on compression, although it ran well.

Then I lowered the transmission slightly to get better access to the upper bolts. Then I removed the crank shaft position sensor.

Next I removed the two large bolts on either side of the transmission that secure it to the block. Then using the proper socket and about three feet of extensions, I removed the two inverse torx bolts from the top of the transmission.

With the transmission loose I began to drop it down. That is when I noticed I had missed one of the bolts that secures the cover plate to the transmission. With that last bolt out, the transmission slid out easily.

The only glitch was that I made my holder too tall and it would not roll out form under the Jeep. I had to use my engine hoist to lift the axle enough to clear the bell housing. I then used the hoist to lower the transmission transfer case unit to the floor.

Then I towed the donor Jeep back out into the yard.

Next I put Jenny’s Jeep in the shop and began disconnecting the stuff under the hood. When I disconnected the transmission control wires I noticed one of the plugs was different and filed that away in my mental notes for later.

The exhaust was broken between the tail pipe and the muffler so I did not have to cut hers to drop it. Otherwise, I used the same procedure to drop her transmission and transfer case as a unit as I did the donor Jeep.

I had a really hard time with the transmission lines on her Jeep however. The plastic quick connect pretty much crumbled away instead of releasing. On one I had to unscrew the coupling from the transmission to get it off the line. The connection to the radiator was easy on hers however because a previous owner had cut off the quick connect and just clamped the hose to the metal line.

While working with the lines however, I think I found the cause of the transmissions early demise. Right at the oil pan both lines were crushed. On line was nearly pinched off. Looks like sometime in its history this Jeep suffered a track bar failure allowing the axle to contact the oil pan and crush the transmission lines. I am sure the transmission had trouble maintain proper pressure and cooling with the restricted flow.

I checked on the price of new lines but the Jeep dealer wanted $170 for the set. I decided to recover the lines from the donor Jeep. It took a while working on the cold wet ground but I finally worked the lines out intact saving all the plastic connectors.

With both transmission on the floor beside each other, I started sorting out the differences in the 92 vs 94 wiring. It turned out he only difference was the speed sensor for the speedometer drive. I planned to change it any way due to possible differences in the speedometer drive gear. It turned out both used the green gear so that would not have been a concern. However, I had to make the swap to have compatible wiring connectors.

After slightly modifying my lift table, I set about reinstalling the transmission. I use a floor jack and a pole under the oil pan to help align the engine with the transmission and it slipped in easily. After installing the two large side bolts, I lowered the assembly slightly to install the two inverse torx bots on the top.

Next I installed the starter and exhaust pipe and the good transmission mount. After raising the assembly close to its proper place I installed the torque converter bolts and replaced the inspection plate.

Jenny’s Jeep is fitted with a transfer case drop to reduce drive line vibration caused by her three inch lift. The drop uses longer bolts and spacer blocks to mount her cross member.

I noticed that her cross member was twisted so I replaced it with the one from the donor Jeep. This one was also pretty beat up from off road abuse but at least it did not have a twist.

As I tightened the bolts I found one of them was stripped out in the unibody. Rather than try a more complicated repair, I found a long all thread bolt and cut off the head to make a stud. I then welded the stud in place in the unibody. Having a stud here actually makes bolting the cross member in place much easier as it keeps the spacer from sliding out on that side.

I welded up her muffler where the tail pipe was broken out. Once it was all in place I set it down and attached the wires and installed the dip stick tube. I then reattached the battery.

A quick test drive showed there was no delay in uptake to drive or reverse unlike the previous transmission. It was well within the 1.2 second spec for engagement even cold.

I headed out of the driveway for a road test. All went fine until I got onto the pavement. It simply refuse to switch out of first gear. I drive a lot of different driving options but to no avail.

Back in the shop, I started reading the trouble shooting guide in Factory Shop manual. failure to shift our of first was not one of the possible failure modes listed in the book!

I next started following the test procedure. The first step was to check for mechanical operation of the transmission. This step involves disconnecting the transmission computer and shifting manually. I dug under the passenger side dash and disconnected the controller.

A test drive showed the transmission functioned perfectly in manual mode. All gears engaged properly. I then plugged back in the computer and it stayed in first gear.

Assuming I had somehow damaged the computer or maybe it was not as compatible between different years as I had been told, I removed the computer from the donor Jeep and connected it to Jenny’s Jeep.

It still stayed in first. Completely stumped, I took a break and posted my question to the XJ list. A reply from Dave had me checking the throttle position sensor, and speed sensor inputs. I saw that the computer used these two inputs to decide when to shift.

The throttle position sensor tested out to within specs. And I assumed that since the speedometer worked, that the speed sensor must work also. However, after some more reading in the shop manual, I noticed there were in fact two speed sensors.

Testing it was a bit difficult due to access to the wires so I first decided to test the one on the floor. Once I figured out where to connect the test leads I saw the sensor made two pulses per revolution of the drive shaft.

When I connected my test leads to the one in the Jeep, it was constantly on and did not change like it was supposed to. I was on to something now.

The biggest trouble was that this sensor is located under a bracket that holds the transmission to the transfer case and holds the shift linkage. It is locate just about the cross member and on top of the transmission.

Access meant supporting the transmission, removing the cross member and lowering the assembly enough to remove the bracket and get to the sensor. Eventually, I accessed the sensor and as I removed it to swap it for the good on, I saw the problem.

The wires had been damaged by the shift linkage when the grommet popped out sometime ago. I guess moving the wires around made then contact in the bare spots as the transmission had been working fine before I pulled it out.

With the replacement sensor in place and all the metal parts bolted back up, I took it for another test drive. This time it shifted perfectly.

I swapped out a few more parts from the donor Jeep like the fan shroud and seat cushions and delivered it back to Jenny. She seemed very happy to have her Jeep back. Especially now that she does not have to wait ten to fifteen minutes from the time she cranks it until she can drive it.

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February 1, 2010February 15, 2010

Jeep Cherokee in the Snow

Jeep Cherokee Off Road — Scuffy in the snow

This weekend I got a chance to play in the snow with my Jeep Cherokee. We don;t get much snow in Cleveland, Tn and when we do it normally does not last long. This weekend however, we got two inches of snow that stuck around for a while.

So I took Scuffy my off road Jeep for a run on the trail behind my barn.

I was very happy with the traction the Maxxis Buckshots had in the wet slush.

Jeep Cherokee in the Snow — Maxxis Buckshots in the snow

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January 8, 2010January 8, 2010

Why I can’t meditate

I have read about and been told repeatedly about the benefits of meditation. However, no matter how hard I, try I just have not been able to do it for more than a few seconds at a time.

The leader of the Unity Church I attend simply says, “Begin again.” But I end up getting frustrated with all the beginning again and I don’t feel I benefit from the meditation that way.

I think I have found my answer in a book of Taoist exercises. In Internal Exercises by Stephen Chang, he explains that people who think a lot – I am pretty sure I qualify – can have disastrous results if they force themselves to empty their brains for meditation. He warns that they will experience confusion, illusion and frustration. In worst cases it can lead to schizophrenia. But mostly it leads to a worsening of the stress and tension one is trying to overcome through meditation.

The solution he recommends is a balancing between the brain and solar plexus. He mentions that the symptoms of cerebral brain over use are headache, stiff neck, confusion, forgetfulness and spaciness. He offers a simple exercise to help balance the mind and body.

The Solar Plexus Exercise:

Begin by sitting or standing with both hands placed on your stomach. Face forward and inhale. Feel your stomach expand with you hands.

While exhaling, push in and up with your hands on you stomach. At the same time, turn your shoulders and head slowly to the left as far as possible without straining.

Face back to the front as you inhale releasing your stomach and feeling the air push your hands out.

This time turn to the right as you exhale.

Repeat up to 36 times or as often as the flexibility of your neck and shoulders will allow.

I have found that after only a few days of doing this exercise, my mental clarity has greatly improved. I have not yet tried to meditate. I will give it a few more days before I try again. I was able to complete a mental focus exercise last night that I have been having trouble with however.

For more information on the solar plexus exercise and many other wonderful Taoist exercises see Internal Exercises by Stephan Chang.

January 8, 2010January 8, 2010

Driving in Southern Snow without Snow Tires.

I live in Tennessee so we rarely get snow. When we do, it is usually not like the snow they get in colder climates. When I worked the Snow*Drift Rally in Michigan, I got to see what driving in real snow was like.

Here we normally get slush. In colder climates, the snow is more powdery and from my experience in Michigan, actually has some traction. The ice however is about the same both places. Except in Michigan, it seemed at times to actually get cold enough for the rubber to stick to the ice. Here, it never does.

In colder climates, they use soft siped tires like Nokians that get great traction in the ice and snow. A set of siped soft compound tires would not last long here as the roads get warm and dry pretty fast.

This morning I woke up to 17 degrees and about 1/2 inch of snow on the driveway. The ground was solidly frozen underneath. This is rare for Tennessee. Normally the ground will still be slushy under the snow.

I actually considered mounting up the Kumho Rally tires to my Jeep, but correctly guessed that the snow would only be on my half mile long dead end road. Once out on the main road the snow was packed to ice. My BFG AT’s get poor traction in snow and ice but the Kumho Rally tires are not much better on ice.

I used the part time setting of my NP 242 transfer case which locks the center differential as I headed down the steep hill of my driveway. The snow and frozen gravel gave plenty of traction. As I made the transition onto pavement, I found it a bit slipperier but still fine.

As I turned off my dead end road onto the secondary road, I found it covered in ice. I could see from the tire tracks in the ditches and from the number of downed signs and mailboxes that it must be pretty slick. I had no trouble accelerating even up hills in Part Time four wheel drive, but I knew stopping would be another matter.

Just before I topped a steep hill, I tested the barking traction and found indeed it was very slick. I was glad I had topped the hill slowly as I saw there were lots of skid marks on the down slope. I am glad I did not meet whoever was trying to get up earlier and left all the marks in the oncoming lane.

One I made it out to the State Highway which had been salted, I found the normal slush and mostly just wet pavement. Here, I switched the NP 242 to Full time opening the center differential. This allows the transfer case to compensate for my unevenly inflated tires and allows cornering without binding.

As I got closer to town, the pavement was mostly dry with occasional slick spots. With the open differential I was able to remain in four wheel drive for added security all the way to my office.

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December 1, 2009December 1, 2009

Black Friday at Wooly’s Off Road

Jeep Cherokee off road at Wooly's off road

Last year my son Scott and I visited Wooly’s Off Road park near Lewisburg, Tn while our wives shopped on the Friday after Thanksgiving. Last year we took his mom’s Cherokee complete with street tires and Motives Makeup decals. We saw enough of the place to know we wanted to go back. It took us a year but we finally made it back to Wooly’s with our off road Jeep.

The trails at Wooly’s straight right out of the parking lot. There are also trails on both sides of the road. Unfortunately they don’t have maps available. There is a crude map on the wall where you check in but nothing to take with us. However the trails are really compact so you really can’t get very lost.

After playing around on the trails a while and exploring, we decided to tackle so of the more challenging obstacles. There is a nice rock climb right behind the barn. As I was going off the top of the climb we saw a couple of Wranglers. They told us about another rock climb near by so we headed over to try it out.

The trial we were on led us to a spot about a quarter way up the climb. It was a narrow trail that intersected at a 90 degree angle. As I tried to maneuver onto the rocks to head up the hill, I got hung up on a stump. I thought I could use it to pivot the back of the jeep down the hill an get the nose pointed up. However, that did not work and I ended up sliding sideways down the hill. After a few dozen back and forth movements while feeling very tippy, I finally got my Jeep pointed up the hill. However in the process, I managed to severely bend one of my newly installed ZJ lower control arms. With the aid of my front locker I made it up the climb relatively easily.

With the control arm bent we decided to take it easy the rest of the day. I went back down to the parking lot and it seemed to track straight so we headed across the street to the less rocky side of the park. I thought this would be a good time for Scott to get more experience behind the wheel.

It took him a few stall to get used to the clutch but after he did he got really good at maneuvering up and down the hills. At one place there are several paths up the same hill. Scott did three or four runs at progressively steeper climbs.

We then headed over to the part of the park where the old home place is located. There we found an old spring house.

We remembered a rock garden that we had tried in Janice’s street Jeep but did not go very far last year. It took us a while to find is because it had become over grown by weeds and briers.

This was a good place for Scott to learn where the tires were and how to place them on the rocks. He ran the course several times taking different lines.

It looked like fun so I decided to give it a run. We played around on some more trails before heading back to the trailer in the early afternoon.

We then decided to explore the south part of the park. With no map, it took us a while to find the right trails to connect to that part. Scott found a really fun climb between two trails. It had large rocks but with good access.

After running this climb several times using different lines, Scott noticed were running low of fuel. We took a long run around the perimeter of the park to make it back to the trailer. Even though there was still daylight left, we decided to pack up an go because we were very tired and there was now fuel station anywhere close.

There is still alot of trails that we never ran. A guide or a map would be a great help. Thinking back, we should have joined up with the two Wranglers and followed them around. But we did have a lot of fun just exploring on our own pace.

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