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

[Katmanken]

You have many more measurements to do with the flywheel removed.

For example, did you measure the OD runout along the length of the adaptor????
If the center hole (in the adaptor) is drilled at an angle, one end will have more run out than another.

DId you measure the face of the adaptor (with the bolt hole pattern)?? Is it flat??? Is it machined at a right angle to the angle of rotation? Does the indicator move when reading that surface and rotating the adaptor on the motor??? A small error there magnifies as wobble of the flywheel.

Do your motor bearings deflect when putting a side load on the adaptor?

Did you measure the bolt hole pattern? If it's off center,, then that could account for the .008 runout is measured at the flywheel. Prolly need a deflecting arm indicator fixed relative to the motor and able to go into each hole as you rotate the adaptor.

With the adaptor removed, measure the runout of the motor shaft as it rotates to see if there is a slight bend to it.

We haven't even started on the flywheel. Porsche or aftermarket????

Ken