I finally got around to filing my old helicomatic's teeth. Well, actually the chrome plating made it impossible to file all but the largest gear, so I used a grinding wheel for the rest. Before the filing, looking at the gear edge-on reveled a little V shaped valley at the top of every tooth. If I had the derailer positioned just right the chain could walk up and the side of each link would settle in that valley and just slide around instead of driving the wheel. Usually happened standing, under load, just as a car was passing too closely on wet pavement or something. Anyway, I separated the gears and filed all but the smallest so that now the top of the tooth ramps toward the next larger gear. That way once the chain gets pulled up to the tops of the teeth it'll slip down and settle into place. Even when I have the derailer positioned between gears it will actually pull the derailer cage against it's spring just a hair and force it into alignment with the larger gear. Noisy, but makes it impossible to float between gears. No effect on shifting to smaller gears except that I don't overshoot as much. My drive train went from pretty hard to shift with a tendency to auto shift under heavy loads to easy shifting and a habit of reliably snapping into place on each gear. Almost feels like indexed shifting. Figured out a handy trick too. I don't have any chain whips, but I do have a chunk of old chain and a vise. I wrapped the chain around the small sprocket, clamped it in the vise, put on some gloves, and was able to unscrew the locking gear from my hub without damage. Took some cussing, but worked.
I finally got around to filing my old helicomatic's teeth. Well, actually the chrome plating made it impossible to file all but the largest gear, so I used a grinding wheel for the rest. Before the filing, looking at the gear edge-on reveled a little V shaped valley at the top of every tooth. If I had the derailer positioned just right the chain could walk up and the side of each link would settle in that valley and just slide around instead of driving the wheel. Usually happened standing, under load, just as a car was passing too closely on wet pavement or something. Anyway, I separated the gears and filed all but the smallest so that now the top of the tooth ramps toward the next larger gear. That way once the chain gets pulled up to the tops of the teeth it'll slip down and settle into place. Even when I have the derailer positioned between gears it will actually pull the derailer cage against it's spring just a hair and force it into alignment with the larger gear. Noisy, but makes it impossible to float between gears. No effect on shifting to smaller gears except that I don't overshoot as much. My drive train went from pretty hard to shift with a tendency to auto shift under heavy loads to easy shifting and a habit of reliably snapping into place on each gear. Almost feels like indexed shifting. Figured out a handy trick too. I don't have any chain whips, but I do have a chunk of old chain and a vise. I wrapped the chain around the small sprocket, clamped it in the vise, put on some gloves, and was able to unscrew the locking gear from my hub without damage. Took some cussing, but worked.
I'm not quite sure what you mean by "pointing outward." My teeth have the smaller radius toward the wheel, like this:
/ | / | | / | | | / | | | | | |-|-|-|-|
I left the smallest gear flat-toothed because it's joined to the next-smallest and I can't get in between to grind. That one hasn't tried to kill me yet, so I'll leave it. Judging by what I can make out on http://www.yellowjersey.org/NWNBOX.JPG Suntour's teeth were sloped the other way. I didn't do it that way because I thought it might make it harder to shift to larger gears. I guess it's not an issue after all. Actually, I can test it by flipping most of the gears around next time I have it apart.
