Replacing unf bolts with metric equivalents

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I found out the hard way that infact the haynes manual is wrong. Stripped the threads just like you. Had to buy some new bolts and cut the old ones off and just tightened the new ones until they're tight (ish)
 
According to my chart the recommended maximum torque applied to an M12 class 12.9 bolt should be 130Nm lubricated or 165Nm dry. For class 4.8 bolts those figure drop to 40/50Nm which is an enormous difference. Is it possible that the original UNF bolts were high tensile, the equivalent of class 12.9 (or even 14.9) and the replacements are just standard bolts and as a consequence aren't up to taking the specified torque?

I wouldn't put it passed certain suppliers to sell cheap Chinese made bolts that aren't made to any recognised standard.
 
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more like that as any one whos tried to remove a land rover bolt knows - factory = dry assembly(or as good as , the bolts may have passed a tub of lube on the way to the factory on the opposite side of the motorway....).

ill bet he has some copperslip/nevrsieze on there....
 
Aframeparts1.jpg


part numbers courtesy of busterbus.
 
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