21-09-2018, 11:09 AM
Several people have now contacted me to say they have seen similar wear when the flywheel is sitting too far back, I will investigate this.
Also received the following:
“I’m more inclined to think that the witness marks are due to wear and chatter and not any sort of manufacturing mark. First off, they look too fresh and bright to be the remnants of the original manufacturing process. Secondly, I don’t think the splines would have been ground as suggested. The tolerance build up indexing from one spline to the next would, I believe, cause a problem and maintaining the accurate shape and size on the grind wheels difficult. Given the large numbers produced I’d expect that the splines would have been finished to size by broaching, possibly using a matched set in a sequence similar to first, second and plug taps. Broaching would be far quicker than grinding each individual spline allowing high production rates and would give good consistent accuracy. This may also explain the mystery of the master spline – it’s included to ensure that each broach (in my imagined matched set sequence) is placed on the shaft in the same angular position as the previous broach in the set.
Ready to be shot down in flames but I’m not sure that you can hob splines on a shaft and leave a master spline?
So if it is wear, what’s causing it? There’s not much of gap once the gearbox is fitted so if the flywheel is sitting slightly too far back the plate could be chattering on the gearbox input shaft female splines. Possible causes, I don’t know, how about the front bearing flange having been repaired positioning the crank slightly too far back, new crankshaft fitted and flywheel ending up slightly backwards, badly worn gearbox bearings, problems with the rear roller main.”
Also received the following:
“I’m more inclined to think that the witness marks are due to wear and chatter and not any sort of manufacturing mark. First off, they look too fresh and bright to be the remnants of the original manufacturing process. Secondly, I don’t think the splines would have been ground as suggested. The tolerance build up indexing from one spline to the next would, I believe, cause a problem and maintaining the accurate shape and size on the grind wheels difficult. Given the large numbers produced I’d expect that the splines would have been finished to size by broaching, possibly using a matched set in a sequence similar to first, second and plug taps. Broaching would be far quicker than grinding each individual spline allowing high production rates and would give good consistent accuracy. This may also explain the mystery of the master spline – it’s included to ensure that each broach (in my imagined matched set sequence) is placed on the shaft in the same angular position as the previous broach in the set.
Ready to be shot down in flames but I’m not sure that you can hob splines on a shaft and leave a master spline?
So if it is wear, what’s causing it? There’s not much of gap once the gearbox is fitted so if the flywheel is sitting slightly too far back the plate could be chattering on the gearbox input shaft female splines. Possible causes, I don’t know, how about the front bearing flange having been repaired positioning the crank slightly too far back, new crankshaft fitted and flywheel ending up slightly backwards, badly worn gearbox bearings, problems with the rear roller main.”