[DeTomaso] halfshaft bolts
JDeRyke at aol.com
JDeRyke at aol.com
Wed Dec 28 02:43:40 EST 2011
Barry, check the heads of the bolts you have with large shanks- they may be
metric marked 'BGM'. I went thru this some years ago (reported in the Feb
'04 POCA Newsletter) and what I thought happened at the time was, all
Mangustas and many early Panteras got 11x 1.5mm, 33mm long METRIC bolts with
matching elastic stop-nuts. No grade was specified. When Ford took control and the
Pantera went into full production in mid- '71, they apparently changed to
the almost identical 7/16-20 SAE bolt with elastic stop-nuts- also with no
grade specified. And the threads are so similar that BOTH the 11mm and the
7/16-20 SAE will untighten using a 5/8" SAE end wrench, and will both screw
together using the other type's unmarked nut- sometimes, with your fingers.
So there's very likely some mixing and matching going on out there....
One thing I did NOT do at the time was check the unthreaded shank
diameters. I assume the production Panteras all got stub axles & halfshafts drilled
for possibly smaller-shank SAE bolts. If you have a friend locally with a
Mangusta that's unmolested, try measuring one of his halfshaft bolt shanks. If
they are the 'big' shank bolts, you can TRY ordering 11mm Mangusta halfshaft
bolts from Wilkinson or others, but I suspect that short-unthreaded-shank
11mm bolts are going to be very difficult to locate.
Remember also, you do NOT need gr-8 (or the comparable gr-10.9 metric):
those are very strong in tensile but not so much in shear- which not exactly
whats needed in this application. Gr-5 (or the comparable gr 8.8 metric) are
much tougher in shear and work better as halfshaft bolts.
At the time I thought I'd settled the metric vs SAE halfshaft bolt thing,
but apparently even after 32 years I can still learn something about these
beasts- J Deryke
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