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]

The adaptor wouldn't be the first part made wrong or have a slightly less than perfect match with the motor shaft. Is the motor off the shelf? if so, the output shaft has a range of outer diameter tolerances that te motor factory uses and you have no control on what you get. Mate that shaft up to the adaptor, and depending on tolerances, you might have a problem.

I'd measure the crap out of that hub adaptor and the assembly of the hub adaptor with the flywheel. There are a lot of variables that can cause the problem. Look for simple stupid stuff too- burrs and the like can cause a small amount of cocking.

Balance is another factor. You have two planes to worry about.

Ken