Originally Posted by KrisZ
Originally Posted by grampi
I don't understand why applying anti-seize to the threads would have an bearing on the torque applied. All the anti-seize does is prevents the threads from locking together when removing the plugs...
That's because torque is directly related to the coefficient of friction of the threads. Most torque specs are provided for dry, clean, freshly machined threads.
Applying any lubricant to the threads will reduce the coefficient of friction and therefore alter the torque wrench reading in the sense that it will take more rotations to achieve the same TQ reading vs. clean and dry threads.
Rust alters the torque reading in opposite fashion. Because if the increase in coefficient of friction, it will take less rotations to achieve the desired torque. Therefore the fastener will in reality be under torqued.
Great explanation! Thank you!
I won't worry too much about 20lbs of torque, because really that isn't much. I'm wondering, too, if there isn't already an anti-seize coating on Champion plugs, anyway. If so, then the 20lb torque spec probably takes it into account. I'll know for sure if it was ok in about 30k miles, I guess. The old V8 idles much smoother now, so mission accomplished.
Originally Posted by grampi
I don't understand why applying anti-seize to the threads would have an bearing on the torque applied. All the anti-seize does is prevents the threads from locking together when removing the plugs...
That's because torque is directly related to the coefficient of friction of the threads. Most torque specs are provided for dry, clean, freshly machined threads.
Applying any lubricant to the threads will reduce the coefficient of friction and therefore alter the torque wrench reading in the sense that it will take more rotations to achieve the same TQ reading vs. clean and dry threads.
Rust alters the torque reading in opposite fashion. Because if the increase in coefficient of friction, it will take less rotations to achieve the desired torque. Therefore the fastener will in reality be under torqued.
Great explanation! Thank you!
I won't worry too much about 20lbs of torque, because really that isn't much. I'm wondering, too, if there isn't already an anti-seize coating on Champion plugs, anyway. If so, then the 20lb torque spec probably takes it into account. I'll know for sure if it was ok in about 30k miles, I guess. The old V8 idles much smoother now, so mission accomplished.
