I recently bought a 99' Cherokee classic and it's a little rough,,, but I've been wanting one for several years and was able to talk my wife into it when I bought a brand new truck and used the "I need a daily driver so I don't rack up miles on the truck" excuse to buy the Jeep. when I bought it I knew it needed several things done to it(i.e. Front axle u-joints, front diff pinion seal, coolant flush, rear brakes) but when buying it i didn't check over everything like I think I should have. I will be the first one to admit that I AM NOT A MECHANIC so I don't pretend to play one. I do know basic mechanics and I am an electro/mechanical tech by trade. To get to the point... I've only had it for a few weeks but have been driving it to work and back almost everyday(about 10miles one way) and have recently noticed some clunking/shimmying in the front end. I tagged it to being the front u-joints needing replaced. Well, I crawled underneath tonight to take a better look at things and when I grabbed the front drive shaft I can get about 1" of rotation in both directions with the car in park... Soooo, is this the transmission or is this the front diff going out? This can't possibly normal.... can it?

Thanks for for any helpful input.

 

Does it have a locker in the front? If so that is normal play.

 

No. It's completely stock as far as I know.

 

I think a little play is normal. I would suspect (and check) other things before blaming the differential.

Are the driveshaft u joints okay?

Check the control arm bushings too. Also there are a bunch of ball joints down in the front, check them out too. Start pulling and pushing and look for movement.

 

I didn't get any play from the driveshaft u joints. I know the axle u joints are bad I just didn't think I should be getting that much play from them. I guess I'll find out. I need to pop the cover off and change fluid when I change the pinion seal anyways.

 

If you have the Dana 30, you are going to need a new pinion nut with a little loctite when you reinstall. If you re-use the old pinion nut, take note of the position of the nut in relation to the pinion threads (count threads) and mark the nut and the pinion shaft so you know when to stop tightening. I think the torque range is 160 foot pounds. Use more loctite.

Also, before you disconnect the drive shaft from the pinion yoke, mark the position of the shaft and the yoke and the pinion so you can re-install everything the same way. those parts have worn down together and maybe give your vibrations if you change their positions.

Also, after you disconnect the driveshaft, feel the drag of the yoke when you turn it by hand. You want the same drag when you put it back together. If, for example, you can't turn it, then you have an issue. The FSM recommends taking off the wheels, rotors and brake calipers before doing this. And they say to use a torque gauge, if have one. The point here is to feel/measure the drag before and after, so you know they match.

Also, when you install the new seal, put grease in the inside collar that mates with the pinion shaft.