I have a stock XJ with 235's, seems to vibe a lot after passing 55mph, just wondering if this is normal. It vibes so much it turns into "hollow box" noise going into the 70-80 range.

 

Get your tires balanced.

 

I do that every 3500-5000, always the same, maybe a tiny bit better for 500 miles.

 

might be time for u joints

 

Possibly, I was told they were fine, along with the drive shafts, not to long ago..

 

If the tires are balanced, I'd also point towards U-joints.

 

Told by whom? I've watched so many customers of mine run around in circles and debunk what I'm telling them for months because "That was just done", only to eventually find out that "That was just done... wrong and needs redone"

 

Is it stock or lifted?

 

bad trans mount or u joints could even be bad wheel bearing

 

If it's lifted could be drive shaft angle and need TC drop and or rear shims as well.

 

Told by brakes plus, tires plus, and a local shop "G&T Automotive", plus I did a little checking myself. Nothing is loose..

 

Its stock, just as I said in the inrto of this post.

 

Maybe I should also mention; Does anyone else have this "lurch" feel if you let off the gas abruptly going 55-65, with a sort of clunk to it?

 

This is a tech issue, so you'll probably see it get moved over there. To answer your question though, everything you're describing would be caused be your rear drive shaft u-joints being bad.

 

Moved to OEM Tech.