Helical cut gearbox.
The new generation of BMW models.
The latest generation of BMW models are characterised by smooth, precision shifting and a highly reliable gearbox. The gearwheels of the 6-speed gearbox are helically cut, as with the current opposed-twin engine models, which ensures even smoother, more precise shifting and significantly fewer running noises when compared to conventional gearboxes.
The compact housing is recessed between the engine and the secondary drive (swinging arm with integrated cardan shaft). The entire gearbox weighs a mere 13 kilogrammes.
The high-strength helical cut splines principle ensures gentler intermeshing, both for quieter running of gear wheels and for precision interlocking of the individual gears. This precision can be felt clearly during shifting. Unlike with conventional motorcycle gearboxes where shifting takes place by the gear wheels moving on the shafts, in helical cut BMW Motorrad gearboxes the gear is changed via a claw shift with three sliding sleeves so that the toothed gears constantly intermesh and are actuated indirectly. The sliding sleeves have the benefit that they are lighter and smaller than shifted toothed gears, which enables them to move more smoothly over the shifting forks on the relevant shafts. This makes for very short yet concise shift travel. The selector drum has a hollow design and is borne on ball bearings to optimise weight and for easier shifting.
The free gearwheels are installed on low-friction needle bearings, while the shafts in turn run on ball bearings. These are known as clean bearings and prevent any ingress from floating particles, ensuring inspection intervals are longer so that transmission oil changes are only required every 40,000 kilometres.
The shifting shaft protrudes on the left of the housing, making guidance of the shift linkage to the gearshift lever on the footrest easier.
Optimal gear shifting with a driving-active 6th gear and short transmission ratio ensures highly impressive traction values. The gearbox is equipped with a potentiometer for display of the individual gears on the multifunction display as standard. This can be replaced while the gearbox is still installed, reducing the time and effort required for maintenance.
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