Front Driveline Vibration

I am getting some vibration from the front driveline. It starts at about 35 MPH and is loudest at about 45 MPH. I've been troubleshooting this problem for a couple of weeks.

I am at about 4 1/2" lift on 32" BFG AT/KO's. I'm using LCA's for a 3" lift so I think my caster should be "close". The vibration was not there when I first went to 4 1/2" and seems to have gotten worse lately, so I dont think my driveline angles are that far off.

I pulled the front driveshaft the other day and replaced the U-Joint on the differential end. The caps did not rotate very smooth and they were "sealed bearings" so I replaced it. The double cardan end seemed to be in good shape ; the joint rotated smoothly and there was not any slop in the joints. The output shaft on the transfer case did not have any slop either. While the driveshaft was off, I drove it for the day and there was not any vibration at all from the front driveline. I replaced the drive shaft and the vibration began again.

The vibration seems a little worse when I'm in 4WD and is real bad when I coast down from about 50 MPH (still in 4WD). This does not happen when I'm in 2WD.

I hear an occasional pop/click in from under the front end from time to time. Not sure if this is related.

I have recently changed the front axle joints and the passenger side carrier bearing. Drivers side carrier is still in good shape.

I'm suspecting problems in the transfer case but I've never messed with one so I'm not sure. It still could be the drive shaft ...

Could I get some advise from you all about what may be the problem here? I'm a research freak and would appreciate some advise.

Les

Because of how it works,a DC joint will not tolerate much wear(especially the centering ball/socket).Also check the slip joint,they get pretty sloppy.Take it to a driveshaft shop and have it checked!

Thanks RCP ... I was sure the problem was in the front drive shaft initially, that's why I had it off. I checked the slip yoke and it seemed to be tight ... no slop. It was even kinda stiff when I slid it in and re-greased it. I'm not very experienced with the double cardan joints, so I was not sure what to look for there. I just looked for obvious "wear" and worked it to feel for any slop. Is there anything to look for in those type of joints that would indicate problems. I'm going to re-read the article on Pirate.com about drive shafts to see if I can pick up some more info there.

I'd like to know of any other areas I need to check besides the drive shaft. I know that is the most likely place for the problem, but it seems OK.

Les

Re: Front Driveline Vibration - Follow Up

Just a follow up for the search archieves ...

I need to keep a better eye on the transfer case fluid level. It was very low (down to less than a pint). After filling up to the necessary level, the vibration was reduced drastically. The remaining vibration is minimal and may be due to wear/damage from my dumba$$ move. This was one of the items I did not think of checking when looking for the causes for the vibration.

Thanks again RCP for your help. You were the only one who took the time to respond and try to help me out. The Search Archieves are a valuble source of information ...

PS: In the initial message I refered to "Carrier" (as in bearing). I should have said "axle hub".