Ive been chasing a clunking/rubbing noise for a couple months now.

I just did a SAS on my 89 pickup, the truck drives great in 2wd. However when i put the truck in 4hi, i cant go over 15-20 mph without a violent clunking noise from the front accompanied by excessive vibration. I rebuilt the front axel myself following the manual. Everything is torqued to specs, new bearings everything is brand new. it has a welded facebook market place 4.88 v6 3rd member that didn't have excessive play and spun smooth when it was out of the truck. I jacked the truck up on all fours and had it in 4wd hubs locked, it sounds louder on the passenger side. It is a rythmic, rubbing sound, and the sound and vibration seem to get worse when im at speed and push the clutch in. it sounds almost as if the burfield is rubbing in the knuckle. The Shafts are brand new RCVs, there is plenty of grease in the knuckle and the burfs. At first i thought it was my driveshaft out of round, so I got a new driveshaft.Then I thought it could be the hub, so i rebuilt a spare hub i have and installed that. Still no change.

I have a couple guesses on what it could be. 1) the welded diff is shot OR the weld in the 3rd member is not allowing the shafts to fully insert into the differential causing the burfield to rub in the knuckle. 2) the axle housing is warped, although when i jacked it up the tires didn't warble and it drives great in 2wd. 3)When i got the new driveshaft i had to drill the transfer case flange, im thinking that i couldve drilled it out of round. I dont beleive that is the case because when i tighten up the driveshaft bolts the flange seats into the cup. 4) Transfer case is shot, but i dont beleive thats the case either cause the noise definetly is coming from the front axel, and loudest on the passenger side. 5) Mismatched gear ratios in the diffs front and rear?? (ive double checked a million times) or could it simply be having a welded diff in the front axel? (I know thats not ideal but in theory it should work) 6) My axle shafts are the wrong spline count, but then i wouldn't have even been able to get the shafts into the diff/housing at all.

I've searched every thread on here and cant find anything close to my problem. Any help is appreciated.

edit* I believe my axle housing is bent a little bit, the burfield was rubbing in the ball of the housing, causing that noise. Replaced a worn spindle bearing and shimmed my knuckle on the passenger a little differently to center the axle/birf in the ball. Once I got the axle shaft to stop rubbing in the housing, I realized that there was also a noise coming from the transfer case when I go in 3rd gear 4 hi. 🤣 it’s okay though because I needed an excuse to get dual cases!

 

My welded rear diff made a noise similar to what you’re describing before it failed. Good luck!

 

Hi LordHelp....
Sounds like u-joint angles on the fr driveshaft......also, is the driveshaft just uj's on each end or do you have a double carden on the transfercase end? If it is double carden then is it binding up? Most of the double cardens have a limited angle they can cycle thru without binding.
Pictures of the driveshaft would help. ZUK

 

driveshaft spins free no issue there. I just posted an edit on the initial post with the solution. Knuckle Was just incorrectly shimmed and the transfer case was making a noise that was adding to my confusion !

 

Pictures of the driveshaft installed with pics of uj angles at both ends. It's common to have a steep angle at the transfercase.....and that could cause a hum at 20 mph.

 

noise is definitely seems internal. Putting a screwdriver up to the transfer case and then my ear up to the screwdriver sounds internal. But I’ll look into it. Would definitely be a lot cheaper than new t case or duals