Vibration in front end

[robx251]

So I have a vibration on my front end I know it isn’t death wobble. It is some sort of harmonic vibration that starts when I go over a bump effect as small as the breaks in the road like going over a bridge and it goes away when I engage 4WD. Then when I disengage 4WD it is normal until I hit another bump. Thoughts?

 

[TrailHunter]

So I have a vibration on my front end I know it isn’t death wobble. It is some sort of harmonic vibration that starts when I go over a bump effect as small as the breaks in the road like going over a bridge and it goes away when I engage 4WD. Then when I disengage 4WD it is normal until I hit another bump. Thoughts

It could be a lot of things... I’d probably start here to see if there is a change:

1. rotate tires
2. Remove the steering stabilizer, and hit some bumps to see if you get death wobble
3. Remove stabalizer & disconnect the front sway bar to see if you get Death wobble
4. Remove front drive shaft

 

[robx251]

It could be a lot of things... I’d probably start here to see if there is a change:

1. rotate tires
2. Remove the steering stabilizer, and hit some bumps to see if you get death wobble
3. Remove stabalizer & disconnect the front sway bar to see if you get Death wobble
4. Remove front drive shaft

1 not a tire vibration
2 it’s not death wobble
3 it’s not death wobble
4 the front drive shaft in a JL does not turn where it has the FAD on the front axle plus it goes away when 4wd is engaged which would cause it to turn

the vibration is a high frequency harmonic that seems like it’s one of the split shafts spinning out of balance

 

[TrailHunter]

1 not a tire vibration
2 it’s not death wobble
3 it’s not death wobble
4 the front drive shaft in a JL does not turn where it has the FAD on the front axle plus it goes aww when 4wd is engaged which would cause it to turn

the vibration is a high frequency harmonic that seems like it’s one of the split shafts spinning out of balance

Gotcha... bad u joint?

 

[robx251]

Those Felt good and it just passed a state inspection

 

[TrailHunter]

Those Felt good and it just passed a state inspection

Vibrations are frustrating... I feel your pain.. I chased one on my GMC for months that I could have sworn was coming from the front of the truck... and ended up being the rear driveshaft.

 

[OverlanderJK]

Those Felt good and it just passed a state inspection

How does a u joint feel good? It either is or it isn’t.

 

[robx251]

How does a u joint feel good? It either is or it isn’t.

it was tight, no slop. felt "good"

 

[robx251]

Vibrations are frustrating... I feel your pain.. I chased one on my GMC for months that I could have sworn was coming from the front of the truck... and ended up being the rear driveshaft.

Thanks. I could only imagine that it is the front where it doesn't change when under acceleration or deceleration or coasting when in 2wd only changes when in 4wd.

 

[robx251]

After looking at some of the information on replacement parts online from Quadratec and a few other places it appears that there is a nylon bushing that goes into the end of one shaft that has a pin from the other shaft in to it. My guess is that this bushing is worn out. and when the FAD is connected it eliminates that slop in the bushing by the collar engaging both shafts.

 

[TrailHunter]

After looking at some of the information on replacement parts online from Quadratec and a few other places it appears that there is a nylon bushing that goes into the end of one shaft that has a pin from the other shaft in to it. My guess is that this bushing is worn out. and when the FAD is connected it eliminates that slop in the bushing by the collar engaging both shafts.

View attachment 372027

Hope thats it.