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Wheel stud fatigue failure from insufficient torque

Post tension cables/rods are also done this way, a rig is set up to pull the nessacary pull force, then the nut/swedge is installed against the tension surface
 
DPittman said:
Yes but I think that is usually in a one time tighten application such as head bolts as once stretched that's where they stay
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I'm not sure what you mean.

As far as I know, it's ALWAYS a one time deal. Too hard to control yield twice.

Head bolts are not normally yielded just torqued, but the frame bolts mentioned earlier are a one-time use yielded application. There may well be yielded applications in specialized applications on cylinder heads like racing or military or perhaps even in other manufacturers heads, but I'm not familiar with that.
 
Susquatch said:
Head bolts are not normally yielded just torqued, but the frame bolts mentioned earlier are a one-time use yielded application. There may well be yielded applications in specialized applications on cylinder heads like racing or military or perhaps even in other manufacturers heads, but I'm not familiar with that.
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Most newer engines use TTY head bolts, a lot of engines have also switched to the torque to, then xx degrees of a turn, rod bolts as well in some applications

However not all are a one and done, eg; gm allows rod bolts in the ls engine to be torqued 3 times before tossing, although I have never come across a TTY head bolts that allows this

Makes the sting of a head gasket job just that much worse when you have to spring another 100$ for silly bolts.....makes a guy think about going to non stretch bolts/studs (typically arp)
 
phaxtris said:
Most newer engines use TTY head bolts, a lot of engines have also switched to the torque to, then xx degrees of a turn, rod bolts as well in some applications
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So much changes. I retired almost 20 years ago. I didn't know that. Now you have me curious about why. Need to call a few colleagues who are still doing engine design.

Edit - don't need to call anybody. They are everywhere now! Isn't anything sacred anymore?
 
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