Alan and you other Nut Cases,
Here is what I have to date with regard to British strength rating codes and
their letter ratings. BTW I sent this same (similar) list out back on
2/4/01, so it should be in the archives, Re: "Unbreako - R, S or T." I've
updated it slightly.
*A* - 28 TONS TENSILE, I've never seen a bolt with this rating in 35 years
of working on British cars.
*B* - UNKNOWN, However the 3/8" Bolts that hold the bumper brackets to the
frame on my BN1 are this rating and I've seen them in other low stress
applications. The 5/16" bolts that hold my air cleaners to the carburetors
on my BN1 are also a "B" rating with the "WODEN" vendor name.
*D* - 45/55 TONS TENSILE, I've seen this listed as 45/55 TT but this would
make it the same as the higher R rating which doesn't seem to make sense. I
have at least one bolt in my collection labeled "BEES 45D55."
*P* - 35 TONS TENSILE, This seems to fit the pattern and this is referenced
somewhere in my research but I don't have any examples. I would suspect
that this SHOULD be a 35/45 strength rating. I've also never seen a "P"
rating code on any bolt.
*R* - 45/55 TONS TENSILE The most common rating code for fasteners on my
BN1and seems so be on most period cars through the end of the 1950s. I have
plenty of bolts labeled "BEES 45R55. According to Phillip Brown at British
Tools & Fasteners, this is roughly equal to a U.S. Grade 5.
*
S* - 50/60 TONS TENSILE, The S rating appears to have replaced the R rating
around 1960 and as you can see it's slightly stronger. I have a bolt in my
collection labeled "RUBERY OWEN S50-60"
*T* - 55/65 TONS TENSILE, I have a bolt labeled "BEES 55T65"
*V* - 65/75 TONS TENSILE, Once again I have an example labeled "BEES 65V75"
I also found a bolt on my three speed transmission with the markings "SPARTS
HT SAE" One of the few non BSF (Whitworth) bolts on the transmission and I
believe that the HT stands for High Tensile, but that's just a SWAG. I have
found other bolts labeled HT in high stress areas on the suspension of my
'60 Bugeye.
Don't we have anyone on the list in the fastener industry (UK) that could
help us out with a reference to these ratings?
Cheers,
Curt
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