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08-10-2011, 08:52am
I think the key indicator is the fact that the shift fork shafts are not bent; they're not in the least bit damaged.
Something to do with gear position wasn't aligned; given that the forks are okay I'm guessing that one causal factor was that the shift fork shafts flexed.
Another may be, as Fineline alluded to, mainshaft flex. This particular engine was hooked up to a R180 Nissan diff via a propshaft with CV joints. The CV closest to the Busa mainshaft (where the sprocket normally sits) is not supported by a bearing. It could be that harmonic dissonance was created in the prop shaft, leading to a whipping effect on the main shaft.
So as short and tough as the main shaft is, there may have been sufficient flex to allow two gears to try and mesh simultaneously when a gear change was attempted. This high torque effect on the cojoined 3-4 drive gears twisted the countershaft.
Actually, the more I think about it, the more the harmonic dissonance theory makes sense. The brinelling (fretting) is more pronounced on the Mainshaft output bearing side than on the clutch side of the countershaft. The engine wasn't running long enough after the incident for that amount of brinelling to occur from the bent countershaft.
Another factor supporting the theory is the state of the shift forks. A logitudinal shunt from a twisted mainshaft would cause the shift fork shafts to flex without necessarily damaging the forks. If anything, the flexible shift fork shafts may have prevented further damage. Is their inclusion an acknowledgement by the Hayabusa engineers that this flex in the main and countershafts exists and that further flexibility, (rather than reinforcement) is a preferred option?
There is no doubting the incredible strength of the Hayabusa gearbox. The torque load on the gears shown above would have shattered a lesser gearbox. Or at the very least stripped a lot of teeth. For teeth to twist and not break like these is testimony to the Hayabusa's toughness.
And as for Pete calling me a flea carrier; you've got a hide you old dog!
I'm actually over your way next week. I'll give you a call.
Camel
Something to do with gear position wasn't aligned; given that the forks are okay I'm guessing that one causal factor was that the shift fork shafts flexed.
Another may be, as Fineline alluded to, mainshaft flex. This particular engine was hooked up to a R180 Nissan diff via a propshaft with CV joints. The CV closest to the Busa mainshaft (where the sprocket normally sits) is not supported by a bearing. It could be that harmonic dissonance was created in the prop shaft, leading to a whipping effect on the main shaft.
So as short and tough as the main shaft is, there may have been sufficient flex to allow two gears to try and mesh simultaneously when a gear change was attempted. This high torque effect on the cojoined 3-4 drive gears twisted the countershaft.
Actually, the more I think about it, the more the harmonic dissonance theory makes sense. The brinelling (fretting) is more pronounced on the Mainshaft output bearing side than on the clutch side of the countershaft. The engine wasn't running long enough after the incident for that amount of brinelling to occur from the bent countershaft.
Another factor supporting the theory is the state of the shift forks. A logitudinal shunt from a twisted mainshaft would cause the shift fork shafts to flex without necessarily damaging the forks. If anything, the flexible shift fork shafts may have prevented further damage. Is their inclusion an acknowledgement by the Hayabusa engineers that this flex in the main and countershafts exists and that further flexibility, (rather than reinforcement) is a preferred option?
There is no doubting the incredible strength of the Hayabusa gearbox. The torque load on the gears shown above would have shattered a lesser gearbox. Or at the very least stripped a lot of teeth. For teeth to twist and not break like these is testimony to the Hayabusa's toughness.
And as for Pete calling me a flea carrier; you've got a hide you old dog!
I'm actually over your way next week. I'll give you a call.
Camel