High RPM vibration (1 Viewer)

[BuzzAZ]

I’ve been chasing this issue for a while and can’t seem to track it down. At high RPM (>3,500) I get what feels like a pulsing vibration. Originally I could recreate the issue in neutral by just holding a higher RPM. That led me to the harmonic balancer that I noticed had a wobble to it. I replaced that, no more wobble, and it’s smooth as silk in neutral now.

Unfortunately I’m still getting it, albeit to a lesser degree, while driving. It’s agnostic to speed and entirely driven by RPM. I think that eliminates U joint issues. From what I can see of the motor mounts they look fine, but I’m not sure how great of a test that is.

Any other thoughts? Motor mounts aren’t super expensive and I think mine are still original, but it seems like it’s a bit of a job and I’m a little short on spare time right now so I thought I’d check in here before throwing parts at it.

 

[Brindleboxer]

Buzz, here is a post about different vibrations and possible links. I know it is not specific to what you are describing but it could provide insight in your analysis.

Driveline Vibration Check List

I have been trying to diagnose a drive line vibration in my truck at around 70mph-80mph its a mechanical vibration and is speed sensitive. any how, i saw this in the LC40's forum and though it would be quite helpful for some of the 80's guys as well. this poster got it from a Jeep forum. looks...

forum.ih8mud.com

 

[BuzzAZ]

Thanks. That’s consistent with what I’ve gathered, but very nice to have it in one spot. There seems to be a bunch of different potential causes for speed-related vibrations, but everything RPM-related is leading me back to the mounts.