G'day,
I stopped by the shop where I buy my nuts and bolts today and purchased
several grade 8 Allen Head Cap Screws (AHCS) (3/8" x 24 x 1 1/4") and some
grade 8 (8 mm) hardened washers. Eight mm washers were purchased because
3/8" washers were too sloppy a fit.
The screws were manufactured by:
Brighton-Best Socket Head Screw Manufacturing Inc.
1665 Heraeus Boulevard
Buford, Georgia 30518-3383
The washers were in a bin without any manufacturer labels.
Using a small grind stone in my Dremel tool the holes in the washers were
increased to a snug fit around the AHCS threads.
The threaded end of the AHCS were machined flat so the over all length (OAL=
)
could be measured accurately.
I've got the whole front suspension system and drive system out of The Blue
Streak so the left final drive flange was clamped in a vice using copper ja=
w
liners to protect the splines.
The inner CV joint housing was placed on top of the final drive flange and
one of the AHCS was screwed in finger tight to keep them together.
A 0.300 in diameter ball bearing was inserted in the socket head of another
AHCS and the OAL was measured with a micrometer (Measurement #1).
A hardened washer was place on that AHCS and it was screwed it into the
inner CV joint housing 180 degrees opposite the one already installed
without any lubrication.
The 3/8" x 24 AHCS takes a 5/16 Allen wrench. I put an adapter on my torque
wrench (McMaster Carr P/N 5274A12 Easy-Read Adjustable Click-Style Torque
Wrench 3/8" SQ Dr, 5-80 ft-lbs/5-110 NM Torque Range) and set to 45 ft lb.
The AHCS was torqued slowly keeping my arm at an angle of 90 degrees
perpendicular to the wrench until it clicked.
The ball bearing was re-inserted in the AHCS socket and the OAL re-measured
(see measurement #2).
The torque wrench was re-set to 75 ft lb and the AHCS was re-torqued.
The ball bearing was re-inserted in the AHCS socket and the OAL re-measured
(see measurement #3).=20
The AHCS was removed from the flange, the ball bearing re-inserted in the
socket and the OAL was re-measured (see measurement #4).
Measurement #1 1.6160
Measurement #2 1.6180 (bolt stretched 0.0020 at 45 ft lb torque)
Measurement #3 1.6218 (bolt stretched 0.0058 at 75 ft lb torque)
Measurement #4 1.6191 (bolt stretched 0.0031 from new length)
Copper based anti-seize grease was applied to the threads and between the
bottom of the head and the hardened washer of a second AHCS and the test wa=
s
repeated.
Measurement #1 1.6097
Measurement #2 1.6130 (bolt stretched 0.0033 at 45 ft lb torque)
Measurement #3 1.6183 (bolt stretched 0.0086 at 75 ft lb torque)
Measurement #4 1.6133 (bolt stretched 0.0036 from new length)
NEW SUBJECT:
Steve Rourke of Cinnabar advised that the OEM bolts P/N 394777 were
available for $2.00 each. They also stock the lock washers P/N MS37 at $1.2=
5
ea.
WHAT I'M GOING TO DO:
Twenty four (24) OEM bolts have been ordered from Cinnabar to fit to The
Blue Streak and Double Trouble. When they arrive the heads will be drilled
for safety wire using a cobalt drill bit. If they fit snugly 3/8" hardened
washers will be used under them; if not 8 MM hardened washers will be
reworked. The OEM bolts will be installed using a bit of oil for
lubrication.
Rob Mueller
Sydney, Australia
75 - Avion - AUS - The Blue Streak
75 - Avion - USA - Double Trouble
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