source of vibration?, car vibrates at ~ 3k RPM Options

[astronomerdave]

My 914 was converted to an electric vehicle; other than having an electric motor instead of a gasoline engine, the drivetrain is the same as you're familiar with. The electric motor has a hub adapter which matches the bolt pattern of the original flywheel. Then I'm using the orig flywheel, clutch, and transmission. The problem is that somewhere around 3000 RPM the car starts to vibrate (and gets worse with increasing RPMs).

Now at least two or maybe three other guys who did this same conversion had similar vibrations and all of them found that they had troubles with their transmissions. So I jumped to conclusions and thought the same. But I just discovered that I get the same vibration whether driving, sitting in neutral, or sitting with the clutch disengaged.

I have my own new theories now but want to hear what some of you other people think.

Thanks,
Dave

p.s. images of the car, including some parts such as the motor, flywheel, etc. can be found here: http://www.halestorm.us/evconstruction.htm

[charliew]

You could put some studs in the adapter and measure off of their sides rotating it slowly. .008 at the outside of the circumferance of the flywheel is not a lot. .002 on the clutch surface is as good as it will get.

You could do a little shade tree engineering and mount a 18 inch or two foot coat hanger on one of the motor mount holes and tape a washer on the end straight up and run the motor without the flywheel and with it, then add the pp and see what it does. The wire should show the vibration depending on the degree of the mounting of the motor assembly.