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Posted by Dan Shockley on Monday, May 18, 2009 at 23:42:23 :
In Reply to: I think I found the problem posted by Will (in IL) on Monday, May 18, 2009 at 22:59:59 :
Will,
I think that the advise from Pirate, coupled with your latest findings provide the full story.
The Pirate discussion cautioned about excessive gap. If you think about the shape of the ring - if there is a gap, and the bolts are torqued down, the ring will deform into a conical shape (more gap at the bead, less at the inner edge). Therefore the load on the bolt head will be highest on the "outside" (largest diameter of the ring) and lowest on the "inside". Such loading will fatigue the bolts as you have experienced.
If there is no gap, then the bolts would all pull down straight. The ring would be pulled level, again. And, the stress on the bolts will be axial. I think that you could accomplish the same thing with spacers.
Grade 8 bolts are actually much less appropriate when there is torsional loading than the Grade 5 bolts. If there is no gap and the load on the bolt is purely axial, then the Grade 8 bolts would be better suited.
I wonder if the bead on the tires you are using is significantly thicker than the bed on Roger and Kevin's tires.
Just my thoughts,
Dan