My 94 GC, 8 banger with AWD has developed a new and interesting quirk.

After about 20 miles, a droning noise begins. It sounds like you are driving on the rumble strip on the side of the highway. Every 100 feet or so, it makes a rumble. I can't tell which tire it comes from, but it feels like the front right. I replaced the hub and CV axle (was bad, not throwing parts it) but the problem remains.

Front diff fluid appears ok, smells like normal rotten gear oil, and wasn't hot when I checked it. Rear is new and looks like Honey.

What should I be looking for and where?

It's 14 miles to work and it started doing this at 13 miles the last two trips into work. I don't have time to **** with it there, but it is definitely getting worse. I am probably going to drive it until whatever it is falls off and then replace it, but that will probably happen when I actually need to be somewhere.

ETA: it pulls to the right when it does this.

 

Well, today I took out the ABS system relay, as it is sounding somewhat like the pulsing noise when one of the brakes is engaged.

It did nothing to curb the noise. This time it went 11 miles of my 14 mile commute before the gremlin awoke.

fluid levels, both front and rear are fine.

Oh, when I turn to one side, the (front right, I believe) wheel sounds like the wheel bearing is shot. It is not, it is brand new and sounding like the one I replaced did.

This comes on rather suddenly, say over 1/2 mile.

When I got to work yesterday, I grabbed one of the guys and asked him to move my car so I could listen for the sound. Guess what it didn't do. It sounded like it should with no symptoms. Reverse out of the parking space seemed to "right" it. Seemed to being the operative phrase.

Scratching my noodle here.

 

Hey, Ranger. I'm scratching my noodle here too, but is it possible you have a brake piston that's not returning properly? It may be dragging enough to heat up and cause the vibration. I had one pin on my ZJ that caused a similar problem. Again, just an idea.

 

hell, I'm out of ideas, that is why I'm asking. The brakes are good, but I'll give it a look. It makes as much sense as anything else I have thought about.

 

Well, That might have been the issue.

Against "regulations", I swapped the thing out today. It was $23, and the other one had was bad when I bought the car.

Any how, I just drove to the corner store and noticed that my alignment was magically restored, and the car shifted a lot quicker than it normally does.

Confirmation Bias? Possibly.

time will tell.

Thanks Dave. I was leaning toward the caliper (as that was all that's left at that corner of the car) but it's still good to hear someone with the same train of thought. At least I can share the blame with you if you are wrong. LOL.

 

I hope that's what it was.

As I was saying, my '97 ZJ had a rear caliper that was dragging because one pin was dry and it was "cocking" itself and heating up. I'd notice for a couple of days that the jeep just didn't seem to have the power it normally did and slowed down faster than normal when I lifted my foot. Then I decided to take a trip to see my buddy about 40 miles away and hit the highway. I didn't notice any problem until the off-ramp. It started vibrating and when I stopped, the rear brake was smoking! The rotor was blue and after letting it cool, seemed to release. I drove carefully to my friends house and we took it apart. All I had to do was grease the pins to get it home. I did NOT take the highway back because I didn't want to chance it, but the brake behaved. Later on, I replaced the rotor and pads, pins and bushings, keeping the caliper itself. One thing I DID learn about greasing the pins. You've got to put grease inside the bushings as well as the pins themselves because the wiper lips will clean the grease off the pins when you put them in.

 

While it is definitely performing better, that rubbing sound comes back after a dozen or so miles. I am going to swap the U-joints and see where that gets me. They needed to be changed anyway and were on the short list to replace, but I really don't see how they could be causing this.

The more likely culprit is the front diff, but those are voodoo to me.

 

The front diff got new guts today. After pressing on the new bearings and putting the new spider gears I was amazed at how "tight" it was.

I have about $200 in parts and about 3 hours into this repair. Being my first time, I had to pay a shop an hour of labor to pull and press the new bearings. so, it would be cheaper to do with a little pre planning.

I am pretty stoked though... running great!