It will be harder when disasembled. I did mine when it was together I installed a old sprocket and carefully with a cut off wheel cut a grove up against the sprocket . The Oring behind the sprocket coller needs to have some pressure on it for it to not leak so get the grove as close to the sprocket as you can or you will have to shim up the space. Tecates are horrible for leaking at the counter shaft due to thinner after market sprockets I always fight to get them shimmed correctly The nut on your 85 actually worked real good for keeping the leaks down if only they were available new.