Ok, jean. Here they are.
 The thickness of the plate is 2.1mm at the center.
 The diameter of the central hole is 78mm
 The inner circle of 6 bolt holes centers on a radius of 48.55mm and the hole dia
 is 10.5mm
 The inner set of 4 lightening holes is centered on a radius of 75.4mm and the
 holes are 30mm in diameter.
 the outer set of 2 lightening holes is centered on a radius of 108mm, elipses
 with 15mm radii and 5mm between 2 rad centers.
 outer 4 bolt holes are centered on a radius of 112.25mm and are 11.3mm in dia.
 there are 4 slots, 8.3x30mm with a tab at 90 degrees to the plate. long axis is
 45 degrees to the radius, centered on the 108mm radius.
 Total radius to top of teeth is 160.6.
 the outer geared ring is 18.2mm deep.
 I did not measure the thickness of the ring gear, or complete depth of flex
 plate along axis of rotation.

 Hope this helps. Measurements may not reflect factory specification. Used a
 digital caliper.
 C. Smith

 Just filling the large holes near the center would be  major
 improvement. That is probably where Dave's cracks started.

 Paul Lamar
                   

I check the inner bolt circle and the mid holes and the RX-8 flexwheel will fit there and the plate thickness is the same


Jean Prudhomme


The advantage to the flat solid flexplate is you can make it any thickness you
want. I would start with .090" thick 4130. The spacer need be only 7/8th of an inch long to put the ring gear in the right position.

Here is another option Jean,
You can move the ring gear closer to the block if you machine a bit
off the starter flange and/or recess Jeff's adapter motor mount plate and use a shorter flexplate spacer. That will give you a bit more room for the alternator. You gain a lot of flexibility with this approach.

Paul Lamar