You might be right on carbon vs. stainless. The loctite sheets all have 'grit blasted steel' and stainless steel as two separate entres. I thought one meant carbon other stainless.
http://tds.loctite.com/tds5/docs/HYSAE-120HP-EN.pdf
Shear Strength
'grit blasted Steel' = 4270psi
Stainless = 3350
Aluminum etched = 4800
Aluminum anodized = 2120
OK do you think maybe there's a difference between hardened and annealed? I'll bet there is. But it might not be enough to make a tangilble difference. Oh Dang I feel another test coming on.
RE: the vibration idea
That's a great theory but they came off before I did anything!?
They just didn't stick. The other adhesives are just fine. The same bar prepared in the same way.
Chris: hahahhahahahha Actually I had a block laying around - I've finally found a use for it!
Well I'm off to try the drop tests on concrete. If anymore come off, .....?
Steve