This may be a simple question but I am having difficulty figuring out how to measure runout/alignment for bellhousing. I have seen a number of pictures and posts of the dial indicator attached to the flywheel, plunger to inside diameter of bell opening.

My question is where/how to locate the dial indicator base.
Doesn't it need to be centered on flywheel PERFECTLY to measure runout?
How would you do that??

I have a feeling this is much simpler than I have made it.

Please help.

As long as the indicator is bolted to the flywheel and pointing (approximatly) straight at inside of the bore on the housing you're fine. Just make sure it has enough travel as mounted to indicate as you turn the engine over.

The motion of the flywheel will make its "own circle" regardless of mounting details.

I bolt the indicator to a piece of strip steel bent cold to shape and bolted to a clutch mounting hole on the flywheel. Bends and mouting position get the indicator positioned.

Thanks!!

I figured it had to be easier than I was making it.

Also check the parallel of the FACE of the transmission mount to the flywheel/ engine. This is a little bit tricky as you must indicate on the face of the bell where the transmission mates. Mount the indicator in a similar fashion to the flywheel, and "rig" it to curve around and work on the face.

Of course do the opposite to check flywheel runout. Mount the indicator somehow on the bell, and indicate on the flywheel surface.