lightened flywheel (balance?)
 

A while ago I picked up a used stock 1.8 flywheel. It had already been resurfaced, so I thought I would bring it to the local automotive machine shop and see about having it lightened, they got it down to about 14lb

http://a244.ac-images.myspacecdn.com...890638da7b.jpg

by taking the heavy ring off of the outside back. They were insistent that there was no need to balance it, so I took there word for it.

Now that I am planning to install the thing i am a little concerned about it. Can anyone back up the idea that the balance is still ok after lightening it like this.

Keep in mind that this is a 1.8 flywheel, so while there were three holes drilled in the outer ring, they were uniformly spaced.

yes, get it balanced

Toss the pilot in it and stick it on the input shaft and see if it rotates on it's own. If so then yes it's out of balance. If not it's probably fine for most engines unless it's a high rpm build. I built an electric Geo Metro and turned the entire flywheel down the od of the pressure plate. (no ring gear needed) I used the method I mentioned to actually balance it myself using a drill and 3/8" bit. It ran smooth as silk to 9000rpm =)

Thanks for the great tip Lazzer, we installed it, on the input shaft it would slowly turn so that one general area was facing down, however it proved difficult to get the pilot bearing perfectly straight, and I am not sure it was running true, which would have thrown off the reading.

Anyway, we decided it was close enough, it didn't hurt that the old one was badly in need of resurfacing, and there was no way to do it on a Sunday.

Cross your fingers.

If it wasn't running perfectly true for testing that shouldn't effect it really considering it's still symmetrically out of true. I should have mentioned we did the same thing to my buddy's '97 and had a very slight rotation doing the "dead man's balance". We bolted it on as it was and the car feels smooth as ever to redline. There's noticable improvement in throttle responce.