I would like to add another link to my drive chain to bring the rear axle back as far as I can. The problem is, the bolts that extends out to push the rear axle backward won't extend far enough. The size is M8-50 (grade 11). I found the size that will fit (M8-60), but its only a grade 8 bolt. Why does this boly have to be grade 11? Why couldn't it be a lower grade bolt? Does it really see that much stress? If this isn't good enough, where can I find a M8-60 in a higher grade?