To add to what I was saying in my previous post, this may be interesting reading for some of you:
http://www.boltscience.com/pages/basics1.htmA bolt should only act as a clamping element in a properly designed joint, and not as a locating element unless the joint is specifically designed that way. In order to use a bolt as a locating element, the bolt should be a shoulder bolt with a precisely dimensioned shank, and the hole has to be precisely drilled to be a tight fit (class 3) or transitional fit (class 4). With a standard drill bit what and regular SAE or metric automotive bolts what you usually have is a clearance hole with a loose fit.
For example:
Say you are using 1/2" grade 8 bolts to hold your suspension arms. You drill a clearance hole with a diameter of 0.500" - 0.505", a small tolerance of 5 thou. A grade 8 bolt has a shank dimension of 0.500" to 0.493". This means you could end up with a clearance of 0.012" between the bolt and the hole. If you are seeing reversing loads (as you do on suspension arms) then you can't rely on that as a locating element because the bolt would be banging back and forth within that hole. While the shear strength of the bolt (~17000 lb) would be enough to withstand suspension loads, the impact forces would eventually destroy the hole. So what's to be done? Use the bolt as a clamping element only. The clamping force of a properly torqued 1/2-20 gr 8 bolt is around 14000 lbs. With a friction coefficient of 0.20 between dry steel parts, your joint would take 2800 lb force before the jointed parts slid on each other an allowed the bolt to see any shear force at all.