Rootes Group used Unified thread size, UNF & UNC. Most of the bolts
on the Sunbeam are UNF. This thread type was implemented during WWII
so USA equipment could be easily serviced in Engand. The angle of
the thread is slightly different from SAE thread used in the USA so an
SAE tap or die will cut material on a UNF bolt or thread. For
complete information you need to look in a machinist handbook.
Grade 5 bolt can usually be found in any good hardware store. Grade 8
bolt are all that a Caterpillar dealer sells. I have purchased many
bolts from my local Caterpillar dealer and I am very satisfied with
their service.
Ron Fraser
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>BTW, are the stock bolts really 1/2 x 20TPI? The same guy who suggested
that grade8 had lower shear strength than grade5 also suggested that the
stock crossmember bolts were Whitworth. At this point I think that
information is also suspect. But, I ran a 1/2 X 20TPI tap down one of the
holes to clean out all the gunk and afterwords it seemed like the stock
bolts fit slightly looser than a new 1/2 X 20TPI bolt I had laying around.
Thought I'd ask before running the tap down the other three holes.
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