Explorer-To-XJ Axle Swap?
Question: I recently purchased an '88 Jeep Cherokee Laredo with a small lift and 32x11.50s. I was driving home one day and the throttle stuck, so I shut it off and coasted it into my drive. Here is where the stupidity came in: I tried pulling it into gear to go up my drive, and in the long run tore up two spiders in the pinion gear. I know, dumb me.
I also have a '94 Ford Explorer XLT at my house and was wondering if I could use the rear axle out of that. I don't know what the gearing is on either of them-all I do know is they both have factory gears.
Scotty B.
via fourwheeler.com
Answer: The Ford Explorer differential has either 3.27:1s or optional 3.73:1s. The '88 XJ could have come with a 3.54:1, 3.73:1, 4.10:1, or 4.56:1 gear ratio. My books are not really clear here, but if I had to guess, it would be 3.54:1. If you're planning on using the Ford rearend, a gear change is maybe is order. It is important that both front and rear ratios match.
A quick way to find out the gear ratio is to place a mark on the tire and a corresponding mark on the ground. Also put a mark on the driveshaft opposite a reference point. Now push the vehicle forward one complete tire revolution and at the same time count the number of turns of the driveshaft. For example, if the driveshaft turns 31/2 times for every single rotation of the tires, then the gear ratio is 3.54:1.
I am not quite sure how one manages to break two spider gears by putting the transmission in gear, but then again, maybe they were damaged from another event and decided that it was now time to break-better in your driveway than on the trail. Seems to me it would be a lot easier to just replace the two spider gears than to swap rearends, as this involves moving the spring pads for proper alignment, and a new driveshaft. The wheel bolt pattern is the same, but you will find that the Ford is a bit narrower but usually doesn't cause any problems.
Now, there is an advantage to the Ford 8.8 in that you're getting a much stronger rear axle, but you will most likely have to build a new rear driveshaft and acquire a flange adapter to hook up the Spicer joint to the pinion flange.
Wants Grand Cherokee Rack Info
Question: Could you please tell what the part number is for the Olympic 4x4 rack you put in the back of "Ain't It Grand-er" Grand Cherokee project?
Terry Hawkins
Montrose, CO
Answer: The part number for the Olympic Mountaineer Rack is 907-154 (323/726-6988, www.olympic4x4products.com), and it fits both the ZJ Grand and the XJ Cherokee. You can find it in the Quadratec catalog or online at www.quadratec.com.
I couldn't be more pleased with the rack. At first I thought that I would only use it for trips as it takes less than a minute to remove. However, it has become so useful that it stays in all the time. The lower area offers great storage for things that may move around or come up and greet you in an accident, and the upper area is perfect for soft items like jackets and such.
AX-15 vs. NV3550: What's The Better Box?
Question: I have a '99 Wrangler Sport with the Dana 44 rear (recently rebuilt), 3.73:1 gear ratio, and the 4.0L engine with about 84,000 miles now. The stock Aisin AX-15 transmission is starting to die on me (the synchronizers are wearing, making it nearly impossible to shift into Second, and Fourth gear grinds as I shift into it if done quickly). I am researching replacements/upgraded transmissions and see that an NV3550 will swap in easily. I have read some forums claiming the NV3550 is not a good swap, and that sticking with the AX-15 is the way to go. I'm hoping you can shed some light on this debate.
Brian McCloskey
Washington, D.C.
Answer: First, I'm kind of surprised that you're having problems with the AX-15, as it has proven itself to be a pretty darn good transmission. I know an owner that has, like, 160,000 miles on his, and another owner who has run 220,000 on his without any problems. Before you swap transmissions, you might consider draining the present gear lube, and perhaps even running it though a strainer like a paint filter to see if there are any pieces or parts in the oil. Keep in mind, you're bound to find some small flakes of shining stuff, as that is just normal wear. Jeep specifications call for 77-90/GL3 gear lubricant, which is pretty standard.
Instead of a swap, I think that I would seriously consider having your local shop order one from a quality rebuilder such as All Trans in Portland. Yes, the 3550 is a very good replacement transmission, and most likely stronger than the AX-15, but when in Neutral-due to the design and clearances-it sounds like someone dropped a can full of rocks inside of it. From my experience, it is also not the best-shifting gearbox. Another choice would be Rockland Standard Gear's (www.rsgear.com/transmission.asp) new five-speed upgrade, appropriately called "The Terminator." It is a direct bolt-in replacement with more torque capacity for extreme duty.