FJ80/3FE mid/neutral throttle vibration (1 Viewer)

[ozarkmud]

I'm getting a weird vibration at mostly neutral throttle settings. If at speed I back off on the gas and am mostly just maintaining speed, I'll feel/hear a vibration. If I back off entirely it goes away. If I accelerate, it usually goes away. Very noticeable downhill with cruise control on.

I also have some driveline clunk. Not sure if related or not. I still need to see if my front driveshaft is 180 degress out of phase or not, although not sure if it'd cause this.

Would appreciate any ideas you can offer. Thank you!

 

[jonheld]

Typically, the vibration felt at the sweet spot between acceleration and deceleration is due to a worn slip yoke or possibly a worn universal joint.
At speed, the 2 halves of the drive shaft will flop around if there is any rotational slop. There should be ZERO rotational movement between the halves of the driveshaft.

 

[ozarkmud]

Typically, the vibration felt at the sweet spot between acceleration and deceleration is due to a worn slip yoke or possibly a worn universal joint.
At speed, the 2 halves of the drive shaft will flop around if there is any rotational slop. There should be ZERO rotational movement between the halves of the driveshaft.

Thank you! I'll check it out. The driveshafts were supposed to have both been recently rebuilt, so I'm hoping it's not that. I guess I can push/pull on it and see if there's any obvious give.

 

[ozarkmud]

I found that my front driveshaft was mounted in phase. I mounted it 90 degrees out of phase and my first test drive seemed promising at cutting down on the vibration quite a bit. Will have to drive it more to confirm.

Edit: Drove some more and the vibration is possibly less, but still should be addressed further. Going out of phase wasn't the silver bullet.