I have a 68 Mustang 200 CID automatic

I have a vibration that I feel in the floor pan, that is only felt while under power. I looked under the car and found nothing loose.

Any ideas what could be causing this?

  • 2
    Welcome to the site. You only feel the vibration when accelerating or anytime the Mustang is in drive? No vibration when braking? No noise, just vibration? Anything else you can tell us? Feb 11, 2017 at 16:04
  • Hi, I've edited your question to make it more on topic, but if you could answer all of @Pᴀᴜʟsᴛᴇʀ2's questions it would make it more on topic as right now the question is very broad and is likely to be closed...
    – George
    Feb 11, 2017 at 16:05
  • yes just under power, not when I put it drive and not when braking, just under the heavier load like when going up hill or just coming of a red light Feb 12, 2017 at 17:48
  • old question..but I'd be checking integrity of motor and transmission mounts.
    – agentp
    Sep 5, 2017 at 17:11
  • If you have the cash ($400) you might consider this interesting NVH app some folks designed. I've been curious how it would behave on cars with known vibration problems.
    – jxramos
    Nov 3, 2017 at 19:52

3 Answers 3


If the driveshaft is out of balance the vibration is speed sensitive. However, if the U-joints are out of phase(running a different angles front and rear) the frequency will be speed sensitive while the amplitude will be power sensitive. A change in the differential orientation (lower for instance) affects phase.


Your driveshaft could be out of balance. Get it looked it. If it breaks under load, you and your vehicle can receive serious damage.


Look get under the car near the end of the trans: put you hand I the drive line try to push up-and-down and right and left . Then go to the rear end and put your hand on the driveline and do the same thing up and down and right and left : checking for dad bearings. I had a 67 v6

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