Jeep is a 1990 4.0 Renix model. So it does have a front axle disconnect.

Ok so I finally swapped in my 4wd and was testing it today while in 4high. Well this is the first time I have ever engaged the front axle for 4wd since owning it. Now I notice there is a clicking sound from the front driver side. Is this a symptom for a bad u-joint on the front shaft? BTW it still clicks if I engage the front axle but in 2wd mode. So the axle is not under load from the Tcase but still clicks until I disengage the axle itself. Clicks when turning and clicks while normal driving.

 

Sounds like a work u-joint to me. Had to replace them on my Ram 1500 twice, about once each 40,000 miles.

 

Ok I just thought Id get a second opinion on it since tearing it down is a ***** and I need to rent a stupid big socket to take the hub off. I'll check the u-joint out tomorrow.

 

You can get under there and grab the front axle shaft and see if it has any play. The u-joint will rattle a bit if it is that.

 

Take the front driveshaft off and engage the axle. Then you'll know.for sure.

 

Ok well I thought it was the u-joint but I highly doubt it now. It seems when Im in 4lo on the trails and turn my wheels and drive I hear a LOUD clunking sound. Like a gear jumping a tooth or something. Im thinking this is my front diff. Its definitely from the front and not the Tcase as I replaced the worn out chain already.

 

Did you check to see if it is the u-joint?

 

The u-joint itself is ticking slightly. But its not real loose or anything. I think its on its way out but not real bad yet. The clunking is definately not a u-joint though. Its bad enough to jerk the truck slightly when in 4WD. Going to pull the diff cover tomorrow to check the gears.

 

"jerk the truck slightly when in 4WD"

On dry pavement or a loose surface such as sand?

 

I was on a trail with dirt and mud. I could hear a loud clunking sound as if a gear was missing a tooth. And it jerked the truck slightly.

 

Be sure to check the pinion and carrier bearings and races to make sure there's no binding. Happened to mine and ended up snapping the yoke.

 

You don't need that giant 36mm socket to do the u-joint. Just undo the 3 12 point bolts on the backside of the hub assembly, and remove the hub with the axle shaft. Make sure to get the right size u-joint, theres 2 available depending on whether you have abs or not.

 

It does it only in four wheel drive? That rules out suspension... Check front axle drive components.

 

Check the front drive shaft splines, when they are worn real bad they can jump spines when under load, and it will cause the jerking you are talking about.

 

<----one more vote for bad u'joint