Posted by Alan Bowes on February 26, 1998 at 18:29:40:
In Reply to: Re: Military nuts and bolts - PS posted by Alan Bowes on February 26, 1998 at 18:10:52:
Sorry, I keep thinking of more things.
Many aluminum blocks have steel thread inserts that effectively increase the amount of contact area with the aluminum, which reduces the necessary number of threads, and reduces uneven loading on the threads. This is not normally the case with cast iron blocks.
Also, if you want to screw a higher-strength fastener into a softer casting/forging/etc., make SURE that the original manufacturer's recommended torque specifications for that application fall somewhere within the allowable torque range for the higher-strength fastener. If the original torque specifications are below the allowable range for the higher-strength fastener, then you should probably go back to the original-strength fastener for that application. The idea is to keep the torque within the proper range for both the fastener AND the threaded part that you are screwing it into.