1996 AWD driveline vibration

[SmoothJimmy]

In addition to the possible grinding bearing posted previously, I also also have a vibration in the drivetrain when under even low load at 1400-1600 rpm. I removed the front driveshaft, drove a little, and the vibration was gone (yes, wheel are chocked so wont roll away when parked). I inspected the driveshaft u-joints and noticed that the front was leaking grease from the spider bearings and felt 'notched' in the middle when rotating the spider through it's range.

Can the front spider be replaced or is a entirely new/rebuilt shaft required?

The rear double cardon spider seals are also leaking grease ...

bit feel smooth when rotated.

Also, there is end-play at the shaft where the front driveshaft connects to the transfer case. I can move the collar that presses on the shaft and connects to the double cardon end of the driveshaft at least 1/8" in-and-out.
Is this normal?

 

[my pos mounty]

Yep, you can replace the U-joints... all of them on the driveshaft.
You mean you have play in the driveshaft, even if the U-joints were good? Or is the play in the transfercase or the differential?

 

[SmoothJimmy]

The play is from within the transfer case. That shaft is supported at each end by a beaing and (there is a circlip that maintains position of the shaft within the case?) Should this shaft have axial play or is something wearing out?

There is some backlash in the transfer case too, as I can rotate the front shaft flange a few degrees. I expect some motion here, since its a chain drive, but not sure how much. Are there specs listed somewhere for this?

The truck has 150k and I have changed my transfer case fluid every 10k miles.

I worry that the axial motion, in concert with the notched u-joints could be causing the vibration. Maybe the u-joints along can do this? The u-joints are not loose, just not smooth thru 100% of their motion range.

I have read that ujoints in the the rear double-cardon of my driveshaft (see pic) cannot be replaced. Is this the case?

 

[my pos mounty]

They have the spring clips, that says to me that It can be replaced. I would mark the orientation of the DC joint before dis-assembly. It was balanced in this orientation and you dont want to lose that.
I dont think a little play after 150K miles is out of the question. I had more

 

[SmoothJimmy]

tore down the front driveshaft and realized what the posters were referring to as the non-serviceable part of the shaft...the cv joint. I was curious about the pattern that appears within the socket end of the joint and a machinist friend stated that it looked like what he called 'chatter' and was possibly a result of a manufacturing process that was done in a hurry.

Any comment on this notion, or are the radial lines in the socket the norm or are they an indication of problems?

 

[1996 Exploder]

I just worked on my 96 AWD and my non servicable joint looked the same! I was missing half the needle bearings and used a washer to retain them, put it back together with new greaseable universal joints. Since I was driving from Colorado to Arizona I was happy the fix took care of the vibrations and grinding noise. I'm not sure how long the cv joint is going to hold, but so far so good. Not bad for 282000 miles!

 

[SmoothJimmy]

Well, just replaced the front driveshaft, wheel bearing assemblies and lower ball joints. All repairs were necessary and solved some of the drivetrain issues I was experiencing.

I was hoping the new front driveshaft would solve a vibration issue between 1300-1600 RPM. Unfiortunately, no. This vibration occurs under slight accel, hard accel, you name it. There is also a sound when coasting that I now believe could be the chain in the TC (sounds kinda like a loose chain on a motorcycle).

This vibration DID NOT occur when the front driveshaft was off. For 'giggles', I dropped the front axle and took some measurements (backlash, pinion-ring interaction with 'gel') and it looked almost like new.

I have never towed with this vehicle but do live in hilly country (SF Bay Area) and the rig has 150+k.

I wonder if the bearings on the front drive part of the TC could be heading south? But why would I only have the vibration within a certain RPM range independent of load?

As posted previously and reponded to by Gavin, there is a bit of end-play in the front shaft of the TC...maybe 1/8 - 1/4", no noticeable deflection in the flange (can push and pull up/down with no obvious movement) and there is a good bit of backlash on the shaft when I twist it (maybe 5+ degrees)