If you get the ARC adaptor, you will have to make a suitable length drawbar with the Clarkson threads, there is no other way around this. A length of 12mm studding with nuts at the top and the lower end turned down to the Clarkson thread would be the easiest way. The middle part of the studding might have to be reduced in diameter to clear the spindle bore, as the standard bore for 7/16 UNF might be tight.
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Edited By old mart on 28/05/2020 14:01:00