Originally Posted by oldmanstyle
Bolts designed to resist shear are completely acceptable and standard in the engineering world. You've probably driven over many bridges where the steel girders are spliced together with nothing but bolts in shear. Check the AISC Steel Manual that structural engineers use to design steel structures, they have page after page of tabulated shear resistance values for different types of bolt/bolt groups/eccentric loadings to make connection design easier.
You are definetely not wrong but it is ideal for all fasteners to be in tension. Depending the bridge, the bolts are taking very little of the load and if they are, there are many bolts and they are almost all in shear. On a bridge there are no "Jesus" nut/bolts (helicopter term, sorry), meaning if one bolt fails the whole bridge won't collapse. The m3 diff has a "Jesus" nut/bolt on the top. I personally feel its bad design, but the engineers at BMW have much more experience then me and there is definetely a reason (maybe its for the simple reason that they want it to fail, or cost came into affect). If there was re-enforcement and a second bolt, I strongly feel the diff wouldn't have broken, look at every other IRS car and they have more then 1 bolt on top (4 botls total at a minimum).