1923 roadster, rebuilt engine and Ruckstell rear end. It has a vibration and at about 30-35 it reaches a peak then drops off but is still there, the kind that numbs your feet and butt after driving for a while. The rods are within 4 grams of each other, the flywheel/magnets balanced, pistons weight the same. No balancing on crank or drums. New bushing in the transmission and wood bands. Car runs strong and has a good amount of driving done with it after rebuild. Bosch distributor with counter weights tied down. He thinks it's the rear end but it's not a pulse type vibration, it's steady and increases as the RPM go up. I think it's the harmonics of the engine. Any thoughts?
Do you notice a vibration at a certain rpm in low gear as well as high? That could help eliminate the chances that it is in the engine. If the vibration only happens at 30-35 it may be wheels/tires
The vibration is there all the time but reaches it's peak at about the speed indicated then drops off.
To update; I just talked to him and he has redone the timing. Seems to run much better but will still need to do a good road test to find out.
Vibrations are always annoying and time consuming to figure out, let us know what you find. Always good to know what cure other people issue so when I have one I can look back and keep trying