Chasing non-throttle vibration--advice?

[Timoss]

Hi, all— Looking for a little help nailing down this vibration in my 80 that I would like to make go away and was wondering if anyone has any suggestions of where to start first. Stats: 97 FZJ80 with OME lift and 35s, new tires, balanced, and fresh alignment alignment.

Vibration occurs when NOT on the gas and is only noticeable at higher speeds (say, above 45mph). So you’re cruising on the highway and lift off the throttle and—brrrrrrrrrrrrrrrrrrrr. Feel it mostly in the front end. Stops as soon as you hit the gas again. This vibration has been there since I’ve had the truck (probably 6 or 7 years now) but has gotten very noticeably worse recently, bad enough to be worrying.

Any thoughts on where to start chasing this down?

Thx!
Timoss
88 62
97 80

 

[DARKNESS]

Sounds like u-joints.

 

[BILT4ME]

It COULD be u-joints.

When was the front axle last rebuilt? I am thinking it could also be the hub spindles in the front axle (the brass bushing) being dry.

The third thing would possibly be pinion bearings loose. Check the U-Joints first (Remember: Driveline UNLOADED), then check the pinion play (rotational as well as lateral) and third, the front spindle bushings.

What are your grease levels in the front axle knuckles?

 

[DARKNESS]

Also good options, and probably all need to be done.

 

[inkpot]

Could also be a worn splines on the slip joint in the middle of the drive shaft. John

 

[Spadone]

This has been a very helpful thread. Looking for some follow up. Did you ever solve the vibration? I have had the exact same thing since my lift and it is getting worse. Looks like I am in for a FAR and possibly a diff rebuild.