Hi Guys;

Over the years I have never come across an exact chart on the Mazda RX7
flanged JIS bolt equivalents.
Most after market replacements are rated 8.8 and 10.9:
  http://www.nutsandbolts.com/bolts-metric-flange-bolts-jis-c-31_161.html

Attached is a bolt torque table taken from the 1993 Technical Data manual:

The Mazda bolts marked with a "6" and "8" seem to roughly correspond to
Metric 8.8 and 9.8 bolts in the smaller sizes based on torque values
compared to many charts I have seen.  The torque values fall off in the
upper sizes, probably due thread sizes and the cast iron to which many
are fastened.

Can anyone confirm the grade for the stock Mazda bolts?


BTW, here is a handy bolt torque calculator.  Of particular interest is
the "nut factor" for non-dry clean threads:

http://home.clear.net.nz/pages/national.torquetools/Converters/bolt-torque3.htm

Thanks
Cary

I don't know how you would find out without testing them.

Paul Lamar