Combines I balanced my chopper it still has vibes

So lemme get this straight, if say a brand new 9660 sts has cracks on the tailboard around the top supports it is most likely due to a chopper imbalanceIJ

We put in new knives and had our rotor balanced on our 9500. With it running wide open I could still feel some vibration. Seemed about like it did before. This was about 700-800hrs ago. I check pretty regularly and I haven't seen the first crack. I assume that some vibration is normal. FWIW Billy

let me straighten you out: the chopper in question is on a 9500. The vibration is pretty small, but it is there. I just want to keep the rear hood from cracking out. GS

what style of chopper do you haveIJ the one where each hammer bolts on or the solid rod across for all the hammers in that rowIJ

Probably hard to say out of season, but I always figure if the tail board is clean your chopper needs balanced. If chaff will pile up on it, it is okay. I have one now that is in deperate need of a balance job. You probably know that on the 9XXX combines the rotor could get loose on the shaft on the left end. You can take a 2x4 and pry up on it to check for play. Since you just had it balanced I would think that this has already been checked. I have had one fixed before and later found that they just put 3 set screws in on the left end of the rotor and centered the shaft, then welded it all up. Didn't last anytime! I have had the best luck with Precision Balance. If the rotor is loose, he will rebuild yours or exchange it.

well i figured it was on an older model, i was just curious if the same applies to new models.

My shaft is from a 97, which is a solid end unlike the earlier ones which can work loose. I don't know if the chaff would stay on the diffuser, it does vibrate just enough you can see it. Thanks for your help, all experience is worthwhile. GS

Well, they all have a set of knives_hammers or whatever you want to call them. They all spin fast enough you wouldn't want to be holding on to it if it was out of balance. I lost a hammer once on my old 6620 and it was obvious that no more forward motion was warranted till the thing was fixed. GS

It has the three sets of solid rods going through all the hammers. I may run it, but I sure would like it better if it was perfectly smooth. GS

that design with the three rods to hold on the hammers is very bad for going out of balance. If you get any amount of straw_chaff inside those hoops that the rods pass through then the rotor goes out of balance. Doesn't take much on a chopper going as fast as they do. You can have it perfectly balanced and then run it for a day and it will be out. If it is reasonably smooth you will have to just live with it. One of my nieghbours has a chopper like yours and he put some bolts through the slides to try to make it more solid on the rear hood. With rocks, sections, retracting fingers, pieces of guards hitting the chopper hammers they don't stay perfect anyway!