Basic Gearbox Problems Rare

Gearbox problems are very rare nowadays, but normally only affect first-to-second upshift. The reason for this is that gearbox ratios are not evenly spaced but are widest apart at the bottom and become closer at the top. As a result, the speed difference and the shift impact are greatest on the first-to-second upshift.

That's why quick shifters normally work better from third upwards. This engagement impact from first to second gear is also transmitted through the gear teeth and then through the gear itself to the shaft. You can imagine what forces act on these gears when you are playing rough with 200 horsepower at the rear wheel. To make the gearboxes last and survive the high tooth-to-tooth pressure, gear surfaces are hardened by a nitride coating.
The rest of the gear must not be hardened because that would make it too brittle, so just the face. It is therefore heat-treated for strength and toughness. Yamaha has had very few failures worldwide and the current problem with the Yamaha YZF-R1 gearbox is a first…

All riders know that if an engine seizes, pulling the clutch frees the rear wheel, allowing a safe, normal stop to be made. But if a gear breaks, dislodging a chunk of metal that becomes jammed in a mesh, the gearbox itself can lock up, and pulling the clutch does not release the rear wheel. Complete loss of control follows.

In other countries where Yamaha sold the YZF-R1, Yamaha replace the transmission free of charge at its dealersships.Tag: Gearbox Recall Yamaha Quick-Shifters Problems Maintenance YZF-R1 Horsepower Gear
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