Yes, the 4th bar is an option on the Massey rotors, as well, and will improve the operation somewhat. I will say, however, that in most conditions it hasn't been necessary and mostly used in edible beans where vines are usually very tough or if very dry, have a tendency to break into small pieces. It might be an improvement in safflower if you're in a very dry situation where heads and stalks are breaking up badly, or in rotten straw. In an axial flow machine, badly broken up trash has to build up in a pile before the strippers can carry it up to the vanes. The extra spiral of bars carries this stuff on to the vanes without allowing it to pack. In IH machines, at least, this appears to have eliminated fires which start in the rotor cage. The wear on your sweeps sounds about normal for OEM. When we mod a rotor, we hardface these, and we don't for sure know how long this lasts, because nobody has been able to wear out a set. Wear on grates -- mainly look for roundness on the leading edge of the crossbars -- if roundness is about halfway across the top of the crossbar, they need attention. Same applies to the threshing concaves.
