Our N7 was sold in 1994 so this is from memory. We had the standard flat helicals that came on the 83 models. I think they were 1" wide by 1_2 thick flat bar. No internet and no Hyperisation in those days so we had to guess for our selves. We used the thin shims under the helicals purely to get a smooth corner against the helicals to allow material to flow instead of being held by the cage holes adjacent to the helical and ground up or to form slow moving wads which always carries seed out. I would have reservations about a very thick protruding shim as it is almost a repeat of a flat helical with the same material flow trouble. Can you use channel helicals with thin flat protruding shims. The channels give a double bite at getting material to flow. The smooth corner created by the shims helps even more with the flow. Just don't cover too much of the cage holes which allow seed and etc to escape from the material. A very thin, very fast moving and moderately turbulent material flow around the cage allows seed to be centrifuged out through the thin layer of material and then through the cage. Interestingly, nobody seems to have had the courage to try using small section, heavy angle iron with the flat towards the live side, as helicals in the P1 series cages instead of the flat bar helicals. I think it could work very well. Yes, we still have, at times, serious losses out of our R62's rotor in the odd crop but have come a long way using the hyperisation ideas on this site as well as trying some of our own, some of which work and some don't. We are going to thin shim the helicals in our R62 this coming season [ Dec 2005 ] and also shim our rotor bars out 10mm across the entire thresher and seperator. We shimmed out the last seperator and discharge rotor bar section 12mms this season [ A terrible season, rainfall, yield and price wise! ] with excellent results in that section, particularly in some very green tough thistles. Shoe loss has never caused us any problems except when the accelerator rolls are worn or in a couple of very small, light seeded type crops. Our harvesting conditions, which are all small seeded crops, ie. wheat and etc. are probably matched some where in the US. but in general are very different to most of the rest of the world so what works in one place does not necessarily work else where. Good luck and Cheers.
