[Lowell W]

I'm gonna take a wild-a$$ed guess at this and say it sounds like two different small vibrations, neither of which is very noticeable alone but which resonate or "beat" together to cause something which feels big. So a small change in frequency of one vibration might be enough to get the two to resonate. Please don't all you engineers jump all over me if I'm wrong: I'm no engineer and I'm just guessin'. As Mr. Fixit suggested: try driving at 60+, then shift to neutral and let the motor idle to determine whether this changes with engine speed. Does the vibration in the steering wheel come and go, also, or does it remain constant at speed? Look at your wheels to see whether you've lost a wheelweight. Check your lug nuts or knock-off's. Check your tire pressure. Have you picked up something in a tire? When did you last have your wheels balanced? Check your driveshaft to see whether you've lost a clip on one of your U-joints, or whether there's a mark from a lost balance weight or something stuck on there.

Usually it's something simple but the strangest things can and do happen. A friend had a newly-reassembled motor start up great, then get sicker and sicker with only a few hours of running. Finally, drawing the obvious conclusion that the motor would have to come apart again, he tore everything down, only to find the rings stuck tightly in the pistons. Further examination revealed the remains of mud-dauber nests in the intake manifold. He had cleaned the manifold and set it aside, giving the wasps an ideal place to nest. When he started the motor, it sucked in what he estimated to be half a cup to a cup of fine grit, which packed in between the pistons and rings.

So...Good luck and let us know what you find.

Lowell

ed: Just hit "Submit" then checked back and read the post about the vibration damper. I haven't seen one go bad but it sounds like a good call to me. If you drive along at 60+, push in the clutch and let the motor idle and the vibration goes away, look there.