Another where's this vibration coming from thread

[Chris G]

Unfortunately, I have a new vibration in the TJ. I’ve spent the past week or so trying to nail down the exact conditions under which it happens so I could come here for some advice as to what to look for before I go out and roll around on the concrete in single-digit Michigan temps to start diagnostics. Here’s what I’ve come up with so far:

-the vibration happens when I am in gear coasting (when I’m driving along and let off the gas)
-it happens in any gear and at any speed
-it does not happen when I’m accelerating or when I’m giving it gas to hold a constant speed
-it does not happen when I have the clutch depressed or if I’m in neutral
-it is more of a rumble I can feel through my feet in the floor rather than a whole vehicle shaking vibration

Has anyone experienced these symptoms before, or does anyone have any ideas?

Thanks!

 

[Wattapunk]

Check driveshaft u-joints. Unbolt the front driveshaft and see if the vibes go away.

 

[Shawn at Tom Wood's]

This of course could be almost anything or possibly several things at once. Here's a good way to check for loose parts on the drive shaft(s) though.

1. A loose part. This could be on the front or rear, both should be checked. on some vehicles, even in 2WD the front shaft is spinning passively. A good test for loose parts is to set your park brake and/or chock the wheels then scoot underneath your vehicle. Give each drive shaft a good hard shake up and down. If you can feel anything moving and/or hear a knocking sound then there is something loose that needs to be replaced or tightened.