Combines 7720 Shake Shake Shake

I am having the same problem on our 66T2 w_915 flex. If I disconnect the connecting chain on the left side of the head which drives the sickle, the shaking stops. But I have looked at EVERYTHING under that head and on the sickle, and can't seem to find anything. It is quite a mystery as the shaking is very inconsistent--sometimes it wants to bounce you out of the cab, but most of the time the whole thing runs as smooth as you could ever expect.

You may be onto something here. I have noticed that the frequency and motion that is involved matches that of the sickle. We had this head on a Massey 750 last year and it was fine but this year the whole flex cutterbar will shake side to side along with the sickle. As I said it matches the shake in the cab. I may have to pull that chain and see if it stops. But what doesnt make sense is that the shake is inconsistent but the motion of the cutterbar is constant. Ill have to see if I can track down the source of the cutterbar moving since it shouldnt be. I think there is a stablizer underneath that may be loose or broke. Ill let you know what I come up with.

I had a similar problem on a 24foot header. Changed the pulley size that drives the wobble box and the shakes disappeared.

shot in the dark here guys but we had a 7720 with a 215 which use do to do the same now it was mentioned about changeing the pulley which drive the sickle..which this means speedeing or slowing up the head...u will find that ur sickle may be running to fast which will cause the vibration this was our case we manually slowed down our sickle by using the variable speed drive belt on the left hand side of the machine....i think from memeory we had to adjust the tension pulley in some way u can do it automaticly but i thing u use the hose from the varible speed to run ur reel lift hope u can follow this it worked for us..hi speeded sickle vibrates when wobble box gets on throw overcauseing a thump so to speak will go away if the knife slows cheers hope ithelps