by Bill Soo

For some time I had been meaning to install a LockRite locker in the back of our '94 Cherokee. The locker had originally been intended for the front of my '93 Ranger, but I had never gotten around to it and I felt that it would make more sense to install it in the Cherokee. However, there was a problem; more than half of the bolts holding the cover plate on were Torx bolts and they were on TIGHT. I had already broken 2 bits and stripped a bolt trying to get the thing off. Since it was my wife's daily driver, I had to wait until she left for a visit back east before I could take more serious measures.

The day after she left, I put the truck up on blocks and proceeded to remove the entire axle. Lars came by to help and between us, we had the axle off and on a stand in short order. An impact hammer helped loosen some bolts, but for the stubborn ones (and stripped ones), we resorted to welding nuts on to the bolt heads. Perhaps the heat helped, but in the end, the bolts came off!

Missing teeth = pooched differential...and yeah, I had welded a truss onto the D35 to prevent housing flex.

We then inspected the diff. There was a gouge in the diff cover that seemed odd....it was if it had been done from the inside but we didn't see how. Then Lars noticed the broken teeth on the ring gear. Not good. We also found metal pieces in the fluid. Obviously, a large chunk of the tooth had broken off and gotten wedged between the ring gear and the diff cover, creating the gouge. While the other gears looked fine, we felt that due to the large amount of metal in the diff fluid, it was probably shot.

So now what?

I had several choices, each with pros and cons:

1. Replace the gears on the D35.
   Pro: Simple. Can also use existing locker.
   Con: expensive and still leaves me with a weak D35.
   
2. Replace the whole D35 with another D35.
   Pro: Simpler, cheaper than above, can use locker.
   Con: still leaves me with a weak D35.
3. Replace the D35 with a Chrysler 8.25 I had lying around.
   Pro: Simple. Stronger axle than D35.
   Con: Wrong gear ratio. Would require new gears AND a new locker. Most expensive option.
4. Replace the D35 with a D44 from a Cherokee.
   Pro: Simple swap. Much stronger axle.
   Con: D44s from Cherokees are in high demand. As such, they are both rare and correspondingly expensive.
5. Replace the D35 with a Ford 8.8 from an Explorer.
   Pro: Same lug nut pattern. Stronger than even a D44. Cheaper since availability was high.
   Con: Most complex solution since all mounts would have to be cut off and new ones fabricated.

Since I didn't want to have to go through this again, I rejected keeping the D35. Since expense was a prime concern, I also rejected the 8.25 and D44 options. That left the Ford 8.8.

The first step was to research this option to see if it was viable. Lars was a big help here as he phoned around various yards to see if they had any axles and if so, what they wanted for it. Meanwhile, I was searching the web for articles on doing this conversion. Most of the articles seemed to agree that it was a relatively painless conversion. The old spring pads would have to be removed and new ones made. In addition, new shock mounts would have to be fabricated. Drum brake cables should hook right up while disk brake cables would require additional mods. Also, a new drive plate adaptor would be required. All of this seemed well within our skills so we went to work.

Lars eventually found a yard that had several axles in stock. They wanted CAD$400 for the drum brake versions and CAD$650 for the disks. Lars felt that we could probably haggle them down somewhat though..... So off we went. Since, as I said, expense was a concern, I had decided to go for the drum brake option. We just needed to find one with 3.73 gears (matching the front of the Cherokee).

At the yard, we went from Explorer to Explorer. None of them had the right gear ratio except for one from an Eddie Bauer Explorer, but that one had disks. In addition, it was missing a number of pieces (rotors, wheel stud, some other bolts). Still, it was either that or wait for another one to show up. Lars accompanied me to the office and talked to the guy. He said he would settle for $500. Still steeper than I wanted, but I decided to go for it. Lars also made sure that the price included a drive shaft. We hoped that there would be some way to adapt the drive plate on the shaft, despite what it said on the Internet.

We went back out to the yard accompanied by one of the mechanics who proceeded to torch the various hangers and bolts connecting the axle to the Explorer. Along with a friendly disposition and an experienced hand, he also possessed a large vocabulary of 4 letter words. Well, maybe not that large....come to think of it, it wasn't many words at all; it was just that he used them in every possible sentence.

The unwitting donor: an Eddie Bauer Edition Ford Explorer

We took the Explorer's drive shaft, just in case the flange-to-yoke adapter would work on the Cherokee. As it turned out, it could.

Well, soon enough the axle was loaded in the trailer, along with the u-bolt plates and drive shaft. Our next stop was a u-bolt shop where they made up some new bolts for us while we waited. Then it was back home.

At the house we cracked open the diff and took a look. The fluid looked good as expected but we also found that the diff contained a limited slip! Granted, they are not terribly useful for off road compared to a locker, but I felt that it was better than nothing.

An inspection of the brakes revealed that some of the bolts were missing and one of the pads was cracked. I had found some bolts on the ground near the Explorer but we were still short a few. In addition, the axle did NOT come with rotors. Fortunately, rotors were available locally for only $30 apiece. So I placed an order for new pads, rotors and sundry odds and ends. Oh and new diff fluid. Since this had a limited slip, I couldn't just use the 75-90W we had in the shop. So another couple of hundred bucks.

One of the missing bolts was a wheel stud. To replace that required removing the axle shaft. I was familiar with the process since I have a Ford 8.8 in the back of my Ranger. The first step is to remove the cross shaft retaining bolt. It's a tight fit, but really small socket wrench can get in there and remove the pin. Unfortunately, only half the pin came out; the other half had broken inside the shaft. Not good. This had happed to me once before on my Ranger. At that time, I took it to a rear end specialist who used a needle to tease the broken piece out. Since I had nothing to loose, I decided to give it a try. I had a dissecting kit I hadn't used since college and it included a number of picks and needles. I started to prod and poke at the broken piece in the hole and was pleasantly surprised to see it move slightly. After about 20 minutes of poking, I finally teased the broken piece out.

As soon as we unloaded the 8.8, we popped it open. It had a limited slip and looked to be in good condition.

Thank God for dissecting tools!

Now to prep the axle. The first step was to cut off all mounting brackets. This basically meant cutting off the spring pads since the shocks mounted to the u-bolt plates. There were also some brackets for a track bar, but I left them on since they weren't in the way. This was the first real test of our new Hypertherm Powermax 600 plasma cutter and it worked quite well. We also used it to cut off the shock mounts on the spring pads. Otherwise they would hit the body since they were now on TOP of the axle (an Explorer is spring under axle, a Cherokee is spring over axle). In addition, we cut off the shock mounts on the old D35. We hoped that we could weld these to the 8.8. After using the cutter, we used an angle grinder to get the tube smooth.

Before doing any cutting though, we first measured all the angles on the D35. Of particular importance were the angles on the spring pads, but we also measured the locations of the shocks, various height measurements etc. In addition, I had some mild 1/2" spacers under the leafs. We decided to forgo these and simply make the new spring pads taller to compensate.

The D35's spring perch and shock mount angles were measured. First, we measured pinion's angle.

Next, we measured the perch and shock mount angles. We could then calculate their angles relative to the pinion, which would be our point of reference when transferring these measurements to the 8.8.

Then we cut off the shock mounts so we could transplant them onto the 8.8.

The pads were made out of 1/4" wall tubing, much beefier than the stock pads. In addition, they were much longer in order to reduce axle wrap. It was a bit tricky cutting the curves; we eventually cut a form out of plywood and used it to guide the plasma cutter. After that, a bit of work with an angle grinder gave us 2 pads that were as well matched as we could make them.

The shock mounts were a lot trickier, but the tolerances are a lot looser as well. In addition, the extra height of the spring pads combined with the thickness of the tube meant that a lot of metal had to be cut off the mounts. A lot easier than having to build them up. Once again, the Hypertherm plasma cutter combined with angle grinder did the work fairly rapidly.

Once the parts were ready we used the notes we had made of the D35 to get the angles lined up on the pads. Of particular importance is making sure the distance between the pads is correct. Do NOT measure to the pumpkin for this! It turns out that the differential is slightly offset to the passenger side so the distances are not the same.

We made our own spring perches from some 2.5" x 2.5" square tube. First we cut them to length and drilled center pin holes.	Next, we cut a template of the axle-tube cut-out for the Hypertherm plasma cutter.	And then we traced the template with the plasma cutter.
The 8.8's original spring perch was ground-off (and yes, the brake backing plate was bent).	Then we positioned on the axle stand so that the pinion would be at the required angle (as measured from the D35).	Then the new spring perch was placed on the axle tube and set to zero degrees.
Once the perch was in place, it was welded.	All done.	To do the shock mounts, we first had to trim them down to the proper length and open up the mounts to fit the 8.8's 3.25" diameter tubes.
Then we used the angle finder to properly locate the mounts onto the axle and welded them in place.

Once I had double checked (and triple checked) the positions, Lars welded the pads on. We again checked the angles and since they were still correct, we did the shock mounts. Our original plan was to box in the spring pads, but since they were already so much stronger than the old pads, we decided to forgo that step.

The next step was to clean the axle and prime it. I used a sandblaster to get some of the rust out of the crevices in the diff, but most of the work was with a wire wheel. I then cleaned it with brake cleaner and shot it with a can of gray primer. When the paint dried, we did a test fit under the Cherokee. Everything lined up great! However, there was a problem. Our original plan was to make the pads taller than neccessary and do away with the 1/2" blocks. It turned out that the centering pins were on the blocks, not the springs so we decided to add them anyway. Now I had even more lift in the back.

Around this time we decided to tackle the problem of attaching the drive shaft to the drive plate. A search of the Internet suggested that a special Spicer adapter plate would be required. Since we had the original Ford adapter plate and my drive shaft though, we thought we'd see how different they really were. We removed the u-joint from the Ford axle and compared it to a spare u-joint I had for my Cherokee. They were the same! We went ahead and removed the old u-joint from the Cherokee drive shaft and then combined the Ford drive plate with the shaft using my new u-joint. It all fit perfectly. Cherokees with 8.25 rear ends (and '94+ YJs) used 1330 rear u-joints, just like the Explorers. (As for why my Cherokee didn't have one at the time of this writing, well, that's another story.)

The Ford brake lines attached to the axle in 3 places. Unfortunately, 2 of those places were the old spring perches. To replace them, I welded on some bolts to act as mounting studs. To prevent the line from turning, I also put a few small beads on the tube. It had been years since I had tried MIG welding, but the Air Liquide M200 welder was very smooth and easy to setup and the auto darkening welding helmet allowed me to put down an even bead the first try.

The brake line mounting stud, plus two weld beads to keep the mounting bracket in place when it's tightened up by the stud.

It looks like it belongs there!

After that, I painted the axle red (it was the only paint I had on hand) and after it had dried, I hooked it up. The first time, when Lars had helped me, it had been a simple job. Doing it by myself was not as simple. Get a friend to help you.

The Ford hydraulic brake lines were longer than the Cherokee lines AND they mounted higher, so I had more slack than before, even though I had a bit more lift. Similarly, the breather tube was higher so that wasn't a problem. The e-brakes though....the connectors on the Explorer and the Cherokee are totally different. I had planned to use the Cherokee cables and form a loop in the end, but I then discovered that one of the cables had seized. I hadn't noticed because we never use the e-brake. So since we had to replace the cable anyway, I decided to go with Grand Cherokee cables. Unfortunately, they were out of stock (and back ordered for several months). So until I get around to hunting in the junk yard, we have no e-brakes.

There were 2 other problems. The Cherokee axle is slightly wider than the Explorer's 8.8. In addition, the Cherokee has negative backspacing rather than positive. The combination puts the tires perilously close to the springs. There is about 1/4" gap between the tires and the springs. I plan to add spacers in the future to increase this gap but for now it's been OK. The other problem related to the offset pumpkin. Maybe it's a Cherokee thing or maybe it's just my crappy muffler, but the rear u-joint constantly hit the muffler. Admittedly, one of the hangers is broken so this may have contributed to the problem. In any event, I solved it by making a hanger out of Ready-Rod and pulling the muffler away from the drive shaft.

After a few thousand KM of driving, I can say that the axle handles well. For one thing, we used to have a slight vibration and noise in the back that is no longer there (broken ring gear teeth in a differential can do that). For another, we don't bottom out when going over a bump anymore. Brakes are as good or better than before. A new master cylinder might make them better still but they are good enough for now. I still haven't gone off road yet so I can't say how well it will do in the rough, but I suspect it will do just fine.