[Diy_efi] OT: torque question for the ME types

[Allyn]

thanks in advance for dealing with my off-topic post. you guys are the
absolute experts on off-the-wall engineering stuff like this, and i have
come up empty in my other searches.

i'm rebuilding a set of 3-piece wheels. bolts in question are the perimiter
bolts (that hold the 3 pieces together). here are the facts:

- wheels are 17"x8" and 17"x11"
- bolts are M6x35mm, 1mm pitch, socket head cap screw (shcs)
- 35 bolts per wheel
- sections go together in such a way that there is no shear stress on any
bolts (only tensile).
- original bolts found on wheels were class 12.9 (and rusting like crazy)

the manufaturer recommended at least grade 10.9, and to torque at ~12
ft-lbs, and no greater than 15 ft-lbs. their torque spec seems pretty
restrictive for a 10.9 bolt.

my intention was to go with a stainless type of shcs, as any of the
10.9/12.9 bolt grades tend to corrode much easier, and in my application the
screw heads are high visibility items. I purchased some 302 stainless bolts
of the same size as those removed. upon inspection, the new bolts were
stamped 'A2'. i did some destructive testing of these items, and was able to
reach 15 ft-lbs with no yield. yielding began at ~18 ft-lbs, and torque
remained at ~19 ft-lbs for one full turn, at which point the bolt shears
near its center.

my guess is that the manufaturer is failing way safe on the bolt grade.

can the A2 (stainless) bolts be sufficient for this task?
perhaps the bolts i purchased are much stronger than they should be?
is there something that i am overlooking?

thanks for any assistance
Al Malventano, ETC(SS), USN


_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi