Combines 820 sickle shaking

I think if i remember rightyou have to change the pully on the wobble box if you go from 1_1_2 to 3" hope this helps.

We have a 1020 flex head that does the same thing although not quite as bad as what your head is. The problem that we had was that the drive shaft that connects the combine to the head had worn as had the shafts (the hex part where the driveshaft slips on). This was whipping carrying the vibration to the knife drive box. Hope this is of some help.

Check underneath the head where the left skid pad (that the wobble box is mounted to) pivot's off the frame, there is a shaft it pivot's on with a plastic bushing on each of the tube it pivot's inside of. Also there is a 3_8" U bolt on each end of that shaft that holds it in place and they both need to be tight. Another place you could be getting a vibration is in the wobble box, with the arm that drives the sickle straight forward clamp the sickle so it can't move and try to turn the wobble box pulley. You shouldn't be able to move the pulley at all without moving the sickle.