Harmonic Balancer break out torque

220629

Well-known member
A recent thread brought up how much torque it takes to remove a HB bolt.

Please add any information that you have here. I don't know how it has any real practical value, but information is most tomes good to have.

So the bolt would actually loosen with engine rotation, which explainss the extreme torque to deformation. And, why if not done correctly, things could go way South.

Regards,

Mark
That, and it’s a big bolt! :thumbup:

Those 240 foot-pounds + 90 degrees on the 10.9 spec bolt gets it into its yield range (I don’t know what the revised one gets?) where it has maximal recoil and thread friction...

-dave
The new bolt is, I believe actually weaker. With the same torque it could deform more. It always leaves me wondering why engineers do something. Going from a one piece key to a two piece makes sense. If the HB comes loose, it is less likely to damage the timing gear. Why they changed to a weaker bolt eludes me.

Regards,

Mark
Weaker bolt torqued to yield may be more resistant to fatigue cranking. It may also have more consistent clamping force. My van had the early bolt and it had loosened to about 95ft-lbs over 100k miles.
Mine’s a 10.9 bolt... my torque wrench reads both ways, so I’ll do my best to measure the break-out torque value when I remove it next week and report that data point.

-dave
Unless corrosion or other factors are involved, I don't believe that a lower break out torque vs original is completely unexpected. It will be interesting to get some data on that.

:cheers: vic
 

Top Bottom