96 xj acceleration chatter

Hey everyone, I just bought a 96 Cherokee Sport. It is in the expected condition for its age and mileage (148,000). Here is the problem: While in 4 high under acceleration under 30 mph there is a chatter, which seems to originate from the front axel. This noise is only noted under acceleration some of the time, and there is no problem in standard two wheel position. I have driven trucks with 4 wheel (snow plowing) so I am aware of the chatter one would feel while turning. I know the feeling of the tires “searching for grip”. This chatter is neither of those things as far as I can tell, unless the jeeps setup is very different from those on pickups. Feels much more mechanical, perhaps there is a problem in the transfer case or the hubs? This is my first jeep and I love it. I want to give it a good tune-up. Any brand suggestions for plugs, wires, cap & roter. I am also considering a carb spacer I saw on eBay. I have got to get the gas mileage up on this thing. Anyhow thanks in advance to all who respond.
-m

Anyone have a GM with 14in steel wheels in need of tires see my other post.

Come on fellas. Surely someone has an opinion on this!

Sorry Zoome. Trying to diagnose symptoms based on sounds are the most difficult. People use chatter, sqeaking, sqealing, grinding, moaning, groaning and all sorts of other adjectives. What some describe as "rubbing", others may describe as binding, etc. As you may know, sound has a way of traveling around making it seem like it comes from one area when it really come sfrom another. This can be really hard to isolate as you drive the vehicle.

Does it do it all the time, or only after you initially engage 4HI? What about the other 4wd positions?

Having said that, I'd start with some basics. More so to rule out other causes that are easier to spot.

Make sure all motor mounts are solid. If one is broken, the engine can torque over and cause the fan to hit the shroud. It could also be the engine mount bolt slapping around in the retaining shield.

Drain and inspect the fluids in the trans and front diff. Drag a magnet through the drain pan and see if there's any metal collected.

Pull the front wheels off and inspect everything. Do the rotors turn smoothly? Everything is tight? Any signs of metal shaving anywhere?

Check the steering linkage. Again, anything loose?

You can also drop the driveshaft and check the u-joints.

Thanks for the advice.
The reason I use the word chatter, is because of the consistency of the noise; cha cha cha cha cha. It feels like something is slipping or not engaging properly. The noise is heard in 4 hi, only under acceleration under 30mph. It is not heard above 30mph. The noise is not with every press of the accelerator. It dose seem to correspond with wheel slippage, which is why I was thinking hubs or transfer case. I have not had an opportunity to use 4 lo, as there is no more snow.
The motor mounts are a good possibility; I will have to check them. This made me think of another symptom that could lead to the motor mounts. A nice clunk when the tranny engages into reverse. The whole jeep kind of drops a bit when this happens.
I have not had a chance to go through all my fluids, with the acceptation of checking the levels, which are fine. I will be doing so very soon.
As far as the front end is concerned. I haven't pulled the wheels myself yet. But I did have 4 new tires put on, and I got an alignment. The shop said there was a minimal amount of play in the steering gear. They didn't mention anything about the brakes. I could assume they are fine, however the shop may not have looked at them. So I will have to check myself. And I just put in a new steering stabilizer (that was fun, dumb ass bolt), while doing so I took a look at the linkage. Everything seemed fine to me.
I think that the mounts will be a good place to start. Unless the clunk into reverse is an indication of something else. I don't know about u joints. I need to get a service manual. I have a Haynes for my Supra but it is kind of crappy. I think I will get a Chilton.
Any other thoughts would be appreciated. Thanks again.
-m

My first thought after reading was Ujoints.

Hello!

Yes, it sounds like U Joints to me too. Mine went out on my 90 XJ last year.

Mine went out on my 90 XJ last year.

That's when this thread ended (over a year ago).