Flywheel Question

[JFP in PA]

One additional word of advice: Always use a proper lubricant, both on the threads and under the bolt heads when doing the flywheel. We prefer the ARP Ultra Torque product for this. Lack of lubrication actually makes the process both less accurate, and harder to accomplish.

[Jamesp]

I'm guessing Jon is an engineer (but not a computer engineer) because he is totally correct. Bolts can be considered (very stiff) springs that are stretched to hold parts together. Torquing a bolt is really a method to estimate bolt stretch. Because most of the turning force to tighten a bolt goes into overcoming friction between the threads, the actual bolt stretching part (pulling the spring tight) is a small percentage of the rotation force (torque) being applied. Worse yet, the friction force between the threads, particularly if they are dry (not lubricated), can vary wildly depending on the thread surface finish (and other factors) which may not be tightly controlled. So the majority of the torque is going into overcoming a friction force that may vary wildly bolt to bolt, and whatever is left over stretches the bolt. This is why bolt stretch is actually measured in high end engine connecting rods, and why it's important in high stress / strain applications like the flywheel to find a way to get all the bolts really close to the same tension (stretch) regardless of the torque required to get there to hold the parts together. A couple of degrees of rotation wont' be a big deal, but just torquing everything to the same high torque number might be.