We have tried large and small wire concaves in our 9870's and every sieve, chaffer,setting concave clearance rotor speed combination we can think of. 85 bu winter wheat trying to keep our losses to 1% or less. Sample looks acceptable but capacity is not. 750 bu. / hr is all we can squeeze out of them right now. We were expecting more like 1000 - 1200 bu / hr in easy threshing standing winter wheat. I see some of you rate a combine in acres / day this type of rating means nothing to me. It's all about productivity / hr. At this point the 9870 sts is not turning our world upside down. I would invite anyone with any suggestions to please help me. We are long long time Deere customers but we are starting to look over the fence from a combine standpoint. Very disappointedOur feeling is that this rifled bullet threshing system may be pushing the material through too fast to allow the grain to fall to the shoe.