91 XJ: front driveshaft double-cardan lubrication

I do. Why do you ask?

Sure you are. He said he wanted to raise the front tires off the ground, then put the tcase in 4HI and set the parking brake and try to turn the front driveshaft. In this case, the front won't turn because the back will be holding it through the tcase. The tcase has to be in 2HI or N for the front to turn while the rear is still on the ground.

The front driveshaft wheels freely in 2WD, but is tied the rear axle in 4WD. Well, it wheels independently of the tcase, but not of the tires.

Jeff, Where did the Original Poster say he wanted to raise the front tires? First post: "If I jack up both front tires of my cherokee, apply the parking brake and put the auto trans in neutral and leave the xfer case in 4WD will I be able to freely rotate the front driveshaft so I can get to all the zerk grease fittings?

Also, what's the double cardan joint ball for? In looking at the exploded diagram of the double cardan joint in the front driveshaft (right next to the xfer case) there is a ball fitting that looks like its got a grease fitting. What I'm wondering is why you need this spring-ball at all. If the spiders are handling all the load from transferring power from the driveshaft through the double cardan joint then what is the point of the ball that goes between the spider and the center yoke in the double cardan joint?" Second post: "Bill, the thing is, I've never even been able to see that grease fitting (for the ball), no matter how much I rotate the front driveshaft. Does the ball and spring put pressure on the spider? Is this how it stops the double-cardan joint from wobbling?" Third post: "The thing is Bill, with the double-cardan joint installed, I can't even see that zerk fitting (for the double-cardan joint ball). The skid plate that holds up the xfer case is right there in the way, but even then the zerk fitting is covered by the knuckle of the spider.

Does the double-cardan joint ball and spring assembly put pressure on the spider to prevent wobbling?

Thanks for all your responses and advice too Bill. I really appreciate it. Were you a mechanic in a previous life (maybe after you were in the army)? What unit were you in when you were in the army?" Forth post: "Bill, I noticed your Chevron station was near (or on) Foothill Blvd. Is that the Foothill Blvd. that runs thru Sylmar, Sun Valley and near Mt. Baldy? Why did you give up on your Chevron station? It looks like your station was a full-serve. I always thought there was a lot of money to be made in automobile service?

Was that pic of the Pomona dragstrip? I think that's the only dragstrip left in Southern California now."

BINGO Ding ding ding, we have a winner!

Right here he said he wants to raise the wheels off the ground.

The answer here is NO.

The reason the answer is no is b ecause he wants to lock the rear brakes and set the tcase to 4WD, I assume 4HI, but the same problem exists with 4LO. The front will not turn because the tcase will be locked down by the rear tires. The tcase has to be in 2HI or in N for the front driveshaft to turn in the conditions he wants to create.

Double cardan joint ball, I read that as ball joint. My mistake.

None of that has anything to do with the ability to turn the front driveshaft. It does talk about how to find the grease fitting, and the OP's difficulty in finding it, but it has nothing at all to do with how to look for it, or of the driveshaft turns in Hi or LO or N.

The grease fitting is a bitch to get to, especially on the front (using my CJ as my point of reference). The rear is a bit easier because the joint opens up a bit more because of the sharper angle that it operates at, and the fact that the skid plate is not in the picture. The front is surrounded by the tcase on two sides, and the skid plate on a third. It might be necessary to physically remove the bolts that hold the front driveshaft to the tcase yoke, then grease the fitting and put the driveshaft back into place.

Me too, it would be wrapped around your neck, and chewing on your nose.