Topic: sheer ratings and replacing zinc plated bolts

[paulages]

somehow, in my careful organizing of everything that came off of my CB550F, i have still managed to misplace some important bolts, such as the upper front engine mounting bolts, and the lower triple tree tightening bolts. the obvious answer to this question would be to err in favor of greater strength, but does anyone know what sheer rating somewhat critical bolts should be replaced with? the NOS bolts say nothing on the heads. is it worth buying bolts with a 7 or 8 sheer rating, or would the run of the mill hardware store zinc plated variety work? anybody have any experience with this? i know with cars this rating can be very important.

[Glenn Stauffer]

Your best best is to use grade 5 bolts at a minimum.  Do you know the torque specs for the bolts you're replacing?  That will tell you a good bit about the grade you need to use.

[paulages]

no, i haven't looked into that yet. i figured that would send me in the right direction, though i assumed that it wouldn't specify a shear rating. i know it's very important for head studs, etc. but i was unsure how much it will matter on certain motorcycle parts. it also seems to me that automobile specs. place much more emphasis on proper torquing of bolts when assembling than with motorcycles. maybe that's just the manuals if dealt with???

[Glenn Stauffer]

I'm pretty sure that there are torque specs in the manauls, but I believe the motorcycle manuals might just show specs for different size bolts in general and specific critical fasteners.  If you look at bolt charts, you'll see that different grades of bolt in the same size have different maximum torque ratings.  Combine that with Honda's specs and you'll have a minimum grade for the particular application.  Are you sure there are no grading marks on the heads of the OEM bolts?  You probably already know this, but If there are no numbers, there are often slash marks.

[paulages]

i'll double check for slash marks when i get to my shop next, but i dont think there were any. thanks for the cross referencing advice, glenn.

[dusterdude]

i agree,grade 5 should be more than enough