Four wheel Drive noises

[NikF]

So i just took my 91 jeep wrangler YJ to jasper this past week on the icefields parkway, and about half way i pulled over to take a break and when i started going again, i noticed a noise coming from the jeep. it only happens when it is in four wheel drive. it sounds kind of metallic, like something is rattling or hitting something. I can only hear it at lower speeds, at higher speeds the jeep gets to loud to hear it anymore. Also i had it in four wheel drive again today and at higher speeds about 110, there is alot more vibration in the jeep than their used to be. If anyone has any ideas of what this could be, that would be greatly appreciated. Also whenever i go over bumps when I'm going slow, it makes a popping noise. I had this problem before and i changed the steering stabilizer and it stopped for about a week and then started again. so i don't know if something else needs to be replaced or maybe i installed the stabilizer wrong. I'm kind of new to automotive repairs. again any ideas would be appreciated.

[fug]

Check your u-joints.

[NikF]

Ok ill take a look, any ideas on the Four wheel drive problem?

[fug]

Bad u-joints could be the cause of both the vibration at higher speeds and the metallic noise you hear at lower speeds.   Also if the ujoints in the front axle are gone you could get the popping noise over bumps or in turns. 

[NikF]

And the U-joints Would cause that only when it is in Four wheel drive? Because neither one of those things happen when it is in 2 wheel drive. I'm just a little confused, like i said im pretty new at this.

[JackstandJohnny]

you ain't gonna figure it out sitting at your computer.....

pull your driveshafts to take a look.  if those ujoints in the driveshafts are bad, th ey will likely be seized and wont move very freely. 
for the fronts, just grab wiggle them, there should be no play. if they move at all your front ujoints (in the axle) are bad.


thats an easy place to start

i'd assume its your front driveshaft cause in a YJ it won't spin in 2wd.  if its not might be something in the diff

[BUKI]

Check your u-joints.

X3. And your slip yoke thingy on your front drive shaft.  (the thing that allows the drive shaft to compress under suspension load). That went on me and tons of vibration. And got worse as time passed.

[homeguy]

I had the same thing happen when I had my XJ... turned out the be the u joints... noise at slow speeds and vibration at high.

[NikF]

Ok I replaced the U joints on the front drive shaft and thy seemed to fix the four wheel drive problem. It still makes noises when I turn corners though. I've replaced the steering column dampener. Any ideas of what it could be?

[JackstandJohnny]

axle shaft ujoints and/or unit bearings.  might as well replace em all at the same time