I dismantled the rear end today and my springs corresponded with the gauge of 0.312" but the length was only 154mm against the Drag listed length of 164mm. So I made up spacers of 12mm thickness. 10mm to get the correct length plus 2mm extra to improve stiffness and keep the tire off the guard. Need more outside temperature to test it.
Ariel 1930 model G special, Ariel SQ4 1957, Norton Commando 750, Norton Mercury, Norton 99, Norton N15CS, Velocette Venom, Velocette Thruxton, Velocette LE x2, Morgan F Super, Calthorpe Ivory 500, Yamaha sr500, Moto Guzzi Falcone