"Torque is used to create tension. Bolts are used to affix two components so that they can resist tensile (pulling apart) and shearing (sliding apart) forces. After the nut has been turned onto the bolt, additional torque causes the nut to turn and stretch the bolt.
When the bolt stretches it becomes a solid spring that clamps the components together. As long as the clamp load is not exceeded by the tensile load, the components won’t be pulled apart. Under shear loads, the increased friction prevents relative motion of the components, preventing material failure.
Proper torque is determined by many factors including but not limited to bolt size, bolt grade or class, thread type, lubed or dry threads, etc."
In the subject application most of the above doesn't apply. The subject bolt is used to pinch the two washers to the spacer tube. It's very likely the washers and spacer tube are "softer" than the bolt. Unless you are using harden washers and spacer tube you will likely deform them trying to achieve bolt stretch. If the bolt is like new (threads) and you use a NEW nylon locking nut and it's assembled clean and dry it will stay together with modest tightening assuming no heat issues. I don't know if the factory used nylon locking nuts but I strongly suggest that you do.