I was faced with the problem of converting an 87 six port to run the 93

style

thrust bearing system to meet a customer's requirements. The trick that

I

came up with involved some machining to the counterweight and the

selective

spacer, along with a custom .035" washer. The solution worked

beautifully and

didn't require the changing of the front counterweight or rebalancing.
Bruce Turrentine

Rob Weinstock wrote:

Bruce,

I just completed this mod on a 1990 13B, normally aspirated engine. When I
compared the original parts with the third generation RX-7 parts, I noticed
that the bearing surface on the 3rd gen counterweight has a larger diameter
to accomodate the bearing plate and the bearing.

The 3rd gen Torrington bearing would have run into the lip on the original
front counterweight. How did you manage to do this without machining the
front counterweight?

I'm not noticing any balance problems, despite having stiffer motor mounts
installed at the same time. But then, I cannot detect a pea under my
mattress, either.

Thanks,

Rob Weinstock

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