Bolt Equivilents

Bolt Equivilents
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Posted by: hcgrant ^®

01/24/2006, 08:09:32

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Hi I'm building a kit car and its going to be SVA tested in a few weeks. The bolts holding the lower straps of the harness came with the kit and are M10's . They are marked 10.9 on the head. The SVA manual says all harness bolts must be 7/16" [ 11.1mm] marked 8.8 or an equivilent strength. Does anyone confirm that 10.9 marked M10 bolts are an equivilent to the 7/16" 8.8 ?

From this website :

The Tensile Strength (TS) for 8.8 bolts =120000 psi and for 10.9 bolts=150000 psi
In shear [I think] the strength of the bolt is preportional to the bolt x-sectional area and the TS
so for 8.8 bolt TS * Area = 120k*96.78mm2 =11614k
and for 10.9 bolt = 150k*78.55 =11782k
Hence I would guess that my M10 -10.9 bolt is slightly stronger than the 7/16" -8.8 bolt

I know this is something of an approximation since I've mixed up ins and mm but I think the answer is right. I'm an electrical engineer not mechanical so I would welcome comments / confirmation of the above,