Bolt Hardness

[idreamidrive]

I think I know that the hardness of the bolt is stamped on the top of the head, but can't find the answer to what the "7" stands for. Snapped the head off the transmission case bolt and trying to figure out if 8.8 hardness will work just fine, or if I need to special order a 10.9 hardness bolt. I am pretty sure the torque spec is 29 ft-lb and I would think an 8.8 m10 bolt would be fine, but want to make sure. I searched, it keeps coming up as "whats the difference between a 6 bolt and 7 bolt....", but maybe my google skills could use some help.

 

[iceman69510]

No, it's tough to find JIS bolt information. Everything out there is ISO. The 7 is the tensile strength rating, in Megapascals.

I talked to the fastener guy at work for you this morning, and he said to use the 8.8, not higher.

 

[idreamidrive]

Thank you