Another day into the mystery vibration and after an analysis on the oscilloscope we can eliminate the crankshaft, pistons and con-rods. A few people have suggested that the Harmonic Balancer might be loose. The rubber in the balancer is supple and the unit is undamaged. It might be that the balancer has not been installed correctly (centred) so it might be worth removing it and reinstalling it. What do people think? What sort of torque setting would be adequate on the main retaining nut? If that doesn’t solve the issue then looking at the flywheel and pressure plate will be next. I don’t know what Pressure Plate assembly has been fitted or what condition it could be in? If it is serviceable and correct for the car then it certainly won’t hurt to have the complete unit properly balanced. I was wondering if the balance could be affected by worn locating Flywheel dowels? Perhaps also there might be no locking tabs washes under the nuts on the flywheel allowing it to become slightly loose? I was also wondering what would happen if the Starter Motor teeth on the Flywheel were worn, damaged or even missing in places how that would affect the balance? All will be revealed if the Harmonic Balancer isn’t the culprit.
It will be very satisfying to resolve this issue and begin to enjoy this lovely car.