Front DS vibes - Crazy question

[RockTracXJ]

94 XJ, HP D30, 241 OR

Here's my story:
The other day I pulled my front driveshaft to help me troubleshoot my driveline vibes. They were still there, perhaps a little less, I couldn't tell for sure. While it was out, I took it to a local driveshaft shop had them re-balance (they did add weights) it and replace the dust cap, which had come into contact with my Rusty's tranny skid plate.

After I got it back, I threw it back in and pulled the rear, figured I would take it in and have it re-balanced as well, this meant driving around in front wheel drive. So, I start driving and it vibrated pretty bad around 30-35 mph. Hmm. That sucks. So, I put the rear ds back in to see if the front would vibe when driving around RWD, like normal. No vibes. So now I'm confused. Why would it vibrate when powering the front, but not when just spinning from driving around? Being a city dweller with no gravel/dirt roads for miles around, I haven't had a chance to put it into 4wd to see if it would vibrate (with both ds). I did put it in 4wd briefly on the pavement, but didn't get a good feel for what was happening.

 

[Lawn Cher']

Are the u-joints original in the front shaft? They could be the source of your vibes and would behave as you describe.

 

[RockTracXJ]

Are the u-joints original in the front shaft? They could be the source of your vibes and would behave as you describe.

No, the previous owner replaced the shaft. I would put the shaft's age at between 1 and 2 years old. The shaft is tight, no movement when pulled on.

 

[cj7xjmj]

Just cause the shaft is "tight" , doesnt mean theat the u-joints are good. Try replacing the U-joints and see what happens.



Patrick