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It is important to have that thick washer to spread the load on that soft aluminum head. 'Cap' bolts can be very strong. I like your thinking. For those bolts, one should be able to get torque (and strength) specs that should answer the obvious questions. Note that the washer on the Saab bolt is not particularily smooth or flat.
As for whether there is enough thread, access to a removed head would clarify that. All that you need is the dimension of the through hole depth in the head. Perhaps SWEDECAR has a head that he can measure.
1.75mm thread pitch seems very course. Are you sure about that?
I found 100mm 10x1.5 bolts for $1.50US on the net, grade 12.9
Alloy hardened bolts of this type will typically snap off in brittle mode before they yield or stretch. So not a stretch bolt. So the stretch method specs might very well deliver higher bolt tensile loads than for a bolt stock bolt that actually goes into yield. This bolt with a 10mm shank will also be stiffer than the stock bolt that is threaded full length and that will increase clamping loads for the same amount a a torque plus angle spec.
I found one reference for 12.9 bolts that does not list a yield strength, just an ultimate strength, which also confirms the no yield, just fracture aspect. But they show the same for 10.9 bolts too.
Proof torque:
12.9 64 ft.lb
10.9 53 ft.lb
As an aluminum head heats up, bolt stress will increase a bit.
grade tensile strength
8.8 120,000 PSI
10.9 150,800
12.9 172,000
I see some 10x1.5x100 fully threaded bolts "available" too.
posted by 68.93.19...
, Tue, 5 Oct 2004 09:39:54, Tue, 5 Oct 2004 10:50:23
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