Hi All
I must have missed this thread when it was first posted but maybe I can shed
some light on original British fasteners, their strength rating codes and
finishes. I have been researching this for years since I decided to do a
concours restoration on my BN1 and I am also take notice of the fasteners on
my very original AN5 as I am getting it on the road.
Here is a listing of all the strength rating codes that I am aware of and
what I've been able to determine so far on their strength ratings. I have
been told that the lower the letter the weaker the fastener is however from
documentation that doesn't always seem to be the case.
A 28 TONS TENSILE
B UNKNOWN
D 45/55 TONS TENSILE
P 35 TONS TENSILE? (this doesn't seem to fit the pattern).
R 45/55 TONS TENSILE (this is the most common rating on older cars of
the
50's and according to Philip Brown of British Tools & Fasteners is
equal to
U.S. Grade 5).
S UNKNOWN (the S code seems to have replaced the R code in the 60's
so
one might assume that the strength rating is the same i.e., 45/55
TONS
TENSILE).
T 55/65 TONS TENSILE
V UNKNOWN (I have found these for the most part on engines where high
strength is needed so once again I assume that its rating to be at
least
55/65 TONS TENSILE).
As far as fasteners that are black oxided, the majority of BSF bolts on my
BN1 were finished this way as well as the "V" rated UNF bolts. I haven't
found any black oxide fasteners on the Bugeye as of yet.
I hope this helps and maybe we have an engineer from England on the list who
can clarify some of this.
Curt Arndt
Carlsbad, CA
'55 BN1, '60 AN5
In a message dated 2/3/01 8:56:07 PM Pacific Standard Time,
rickfisk@concentric.net writes:
<< The steering column bolt on my '59 Sprite has the markings "Wiley" with a
"T" underneath it.
Rick
----- Original Message -----
From: <Daniel1312@aol.com>
To: <spridgets@autox.team.net>
Sent: Saturday, February 03, 2001 6:21 PM
Subject: Unbreako - R, S, or T
> Hi list,
>
> Remember my question about the steering column bolt a while back? I was
> trying to establish if the fact that it was black made any difference or
if
> it had a T marking on it.
>
> I think it was the largest Sprite driver in the world (not recognised
> officially) who said he had a bolt with the marking Unbreako on it.
Looking
> at some old bolts I have, one has Unbreako on it but also the letter S.
So,
> anyone fancy checking any black Unbreako bolts to see if it has a T on it.
>
> I think the T is significant because an S bolt is stronger than an R bolt
and
> so I would expect a T bolt to be stronger than an S bolt.
>
>
> Daniel1312 >>
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