I would like to suggest that every one consider replacing the 4 swing arm pivot bolt with 6" X 5/8" bolts and tighten them very tight so that the caps on the end and the spacer become one with frame so that the bearings in the swing arm and bearings pivot on the spacer and not the spacer on the bolt. You may also want to put a zerk in the middle of each mounting bracket. The 6" bolt assures there is enough shank to pass through both mounting tabs. You will need some washers also.
6" X 5/8" bolts are readily available and much less expensive that M16 bolts that probably don't have the 100mm (min) shank.
At a minimum. go tighten the bolts you have, very tight!!!!! Add some grease too.
Jeff
Photos later, maybe