PeachParts Mercedes-Benz Forum - SCORE! bulk grade 12.9 crank pulley bolts!

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- - SCORE! bulk grade 12.9 crank pulley bolts! (http://www.peachparts.com/shopforum/mercedes-benz-used-parts-sale-wanted/305779-score-bulk-grade-12-9-crank-pulley-bolts.html)

I'm in the middle of tearing apart my engine to replace the timing chain guides, and I've read on the forum that sometimes the crank pulley hex socket screws can shear.

so I decided to go ahead and replace the six of them with new screws. this began a journey into learning about hex socket screws.

so then I started searching online for hex screws, and I stumbled upon this:

http://i.imgur.com/U8uhx.png

score! the size I need in 12.9 strength, at $0.30 a piece!

I only need 6 of them, so if anyone else is planning on having their crank pulley off in the near future, PM me and I'll ship some to you.

more on the metric strength grades from Metric Bolt Properties, Grades, and Strength

Quote:

ISO metric fastener material strength property classes (grades). As given in ISO 898-1, ISO metric fastener material property classes (grades) should be used. For example, fastener material ISO property class 5.8 means nominal (minimum) tensile ultimate strength 500 MPa and nominal (minimum) tensile yield strength 0.8 times tensile ultimate strength or 0.8(500) = 400 MPa. (In a few cases, the actual tensile ultimate strength may be approximately 20 MPa higher than nominal tensile ultimate strength indicated via the nominal property class code. Consult Table 10, below, for exact values.) Many anchor bolts (L, J, and U bolts, and threaded rod) are made from low carbon steel grades, such as ISO classes 4.6, 4.8, and 5.8.

so 12.9 means 1,200 mega pascals ultimate tensile strength, and the minimum yield tensile strength is 90% of that.