Not to make Nick feel bad, but this may help everyone else. This is an
excerpt from flywheel article that appeared in the last 6PACK club magazine
(just another reason to join the club, so you know about these things!). So
there is nothing wrong with the way Fidanza produces the flywheels, they
produce the bolt holes for a literal 7/16" sized bolt... your machine shop
should be able to ream out the bolt holes so that the ARP bolts are a very
snug fit in the holes. We do this all the time, I've been doing this to the
TR6 aluminum flywheels for years... you shouldn't have to pay more than
$15-$20 for the reaming of the four holes.
Excerpt:
"What is needed to reliably hold your flywheel to your crankshaft are some
very high tensile strength bolts that arent brittle. ARP flywheel bolts
work great and have a very broad under-head area to spread the clamping.
The stock Triumph flywheel bolts were not all that bad either and very
similar in design to the ARP bolt, but of a weaker material. I do not like
some of the currently supplied flywheel bolts being sold by major parts
vendors. The stock flywheel bolt is 7/16 in diameter for the threaded
section and has a larger diameter shoulder area under the bolt head. The
ARP bolt also has a wider unthreaded shoulder section. Some replacement
bolts are also 7/16 in diameter, but do not have this wider shoulder area
and they also have a small groove cut into the unthreaded shoulder which
actually decreases the tensile strength of the fastener as the root diameter
of the bolt is now reduced with this groove. I strongly recommend the ARP
bolts for fastening all flywheels on our Triumph engines.
A helpful tip if you are fitting ARP bolts to an aluminum flywheel. Your
aluminum flywheel will need to have the mounting bolts reamed out slightly
oversize to fit the wide ARP shoulder. "
--
Kai M. Radicke
Wishbone Classics
* British Car Parts *
www.wbclassics.com
Ph: 215.945.7250
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