Spring Spacers are available for John Deere 60, 90 and ProSeries openers, including the 750a, 1560, 1860, 1590, 1690, 1890, 1990 and 1895. They are 1/2″ thick and easily install in the spring assembly to increase the opener down-pressure by 75-90 lb.
They are required in the openers behind the tractor wheel tracks and/or air-cart wheel tracks, to increase the down pressure in these lower/compacted areas (relative to all other rows), to maintain a more consistent seeding depth.
Most drills and air-seeders require around 3 spring spacers per tire on 7.5″ spacing and around 2 per tire on 10″ spacing, but measure the width of the tires (relative to the row unit locations) to be sure.