Exploder
I have a chance to buy a complete '97 Ford Explorer 3.73 posi rear axle assembly for $150 delivered. I want to put it in my Jeep Cherokee XJ. My Jeep also has 3.73 gears. Basically, what do I need to do to adapt it? I heard it's a good swap and pretty easy. Do I need to relocate spring and shock mounts? What about driveshaft attachment?
Ken Freund
Via email
Have you had your XJ regeared? Most came from the factory with 3.55 gears. I'd double-check unless you've had your axles regeared to 3.73 and know for sure. If you do have 3.55s, I'd gear the front to match the Explorer rear.
The '95-up Explorer rear axles have a slightly larger 8.8-inch ring gear versus the 8.5-inch ring gear of the '94-earlier axles. They also come equipped with good 31-spline axleshafts and disc brakes. The Explorer axle is a bit narrower than the factory TJ/XJ axle (about 1.25 inches), so you may consider using some 1.25-inch-wide (2.5-inch increase overall) Spidertrax, Poly Performance, Rugged Ridge, or other wheel spacers on the rear if you run into tire-to-Unitbody interference issues. Or, if you don't want to go that wide, M.O.R.E. (mountainoffroad.com) offers some thinner 7/8-inch thick (1.75-inch increase overall) spacers.
You will need to remove the spring perches and shock mounts from the Explorer axle and flip them. Explorers are spring-under, while the XJ is spring-over. If you cut them off carefully, you'll be able to reuse them and weld them back on up top. If you don't feel like reusing the stock stuff, M.O.R.E. makes a nice Explorer installation kit for Jeep vehicles with the included spring perches, shock mounts, and hardware.
You will probably be able to hook your Unitbody-to-axle brake line right up. The Explorer uses two factory rubber lines off the calipers that connect to hard lines routed along the axletubes to the top of the pumpkin with a single T-fitting to a flexible axle-to-frame hose. The Explorer axle-to-frame hose is longer than the XJ one, so use that if it's still on the axle. I'm pretty sure that the thread is the same as the hard line on the XJ Unitbody.
If you've got the E-brake cables attached to the Explorer rear axle there's a chance they may hook up to your XJ's E-brake cables, but usually most guys pull the trigger on a Lokar Explorer cable kit (PN EC-81FU). The Explorer disc brakes are the foundation for many aftermarket disc brake upgrades in 4x4s and hot rods, so there's very good aftermarket support for this sort of thing. Or if you want a more factory-type installation, M.O.R.E. offers the correct cables (PN EB-3 for '97-up XJ or PN EB-2 for '84-'96 XJ).
Finally, the Explorer axle uses a driveshaft flange, not a U-bolt yoke. Most good driveshaft companies offer conversion adapters to mate the Explorer flange to a 1310 U-joint. JE Reel Driveline Specialists (reeldriveline.com) can get you the Spicer-brand adapter (PN 2-2-1379) and metric retaining bolts to mate your driveshaft to the Explorer flange. M.O.R.E. also sells the flange. You'll still need to check your overall driveshaft running length to determine if your shaft needs shortening or lengthening. Most will drop right on with no length modifications. Or you can avoid all of this conversion fuss and use a later-model XJ 8.25 rear axle and bolt it in, because this swap doesn't get you much extra if you already have the 8.25.