Beware that many of the 5/8" dia bolts sold as such are not suitable since they are threaded too far down the bolt, meaning that the lower fork of the radius rod is bearing on the thread and not on the smooth shank. Result - accelerated wear on the lower fork.
Bertie Dunlop kindly made me a suitable bolt by cutting down a 7" bolt and cutting the thread a bit. Here's the result, Dunlop bolt upper and incorrect bolt lower:
Dimensions for the Dunlop bolt are length of plain shank from under head 4.1/2", total length of bolt 5.1/2", with 5/8" UNF thread extending 1".
Fits perfectly.
