Superior Shifting?
SUPERIOR SHIFTING?
AT DUCATI's WINTER TEST sessions in Valencia, Spain, and Kyalami, South Africa, the factory 996Rs ridden by Troy Bayliss, Ben Bostrom and Ruben Xaus were mules for ideas perhaps soon to be seen in Grand Prix racing. The bikes carried Marelli's Selespeed automated clutching and shifting system developed from those used on Formula One cars, and now appearing on certain Alfa Romeo, Aston Martin and Ferrari production mod els. This is exciting because it will reduce operator workload, setting free mental attention to be better applied to engaging the enemy more closely.
Why not just go straight to automatic transmissions or CVTs? Other companies tried them (Honda CB750A) and the public rejected their Dynaflow engine moan. Existing clutches and gearboxes are proven components, and for racing, a multispeed gear transmission is lighter and more power efficient. It also allows rapid tailoring of internal ratios to specific circuits. People who have driven production cars equipped with the system say it is wonderful-except when you hand the car to a parking jockey.
How does it work? In the automotive version, shifting is performed hydraulically, and the clutch is operated by a very sensitive electronically controlled proportional servovalve. There is also a throttle positioner.
There are two modes of operation: auto and manual. To drive away in auto mode, you step on the throttle and the system launches the car-no bogging ever.
The more you
you open the throttle, the harder it launches. The revs at upshift rise with throttle opening, taking the engine to redline at WOT. When you brake, the system downshifts appropriately.
In manual mode, gear changes are triggered using the much publicized “paddles” seen on F-l car steering wheels-one for upshifts, one for downshifts. Alternatively, a “rowing stick” can control shifting. Push it one way for upshifts, the other for downshifts. Hydraulic power for the system comes from a pump, driven either electrically or from the car’s engine, then stored at high pressure in an accumulator.
In the motorcycle system tested by Ducati, the shift sector is reportedly actuated by two electrical solenoids because room for hydraulics is lacking. An up/down shift control is located on the left handlebar. Selespeed is said to add about 11 pounds of weight.
Much simpler shift aids-shifter switches-have been used for about 10 years in motorcycle roadracing. These allow upshifts to be made without rolling off the throttle. The shift-lever-actuated switch, acting through a delay box, cuts off the engine’s ignition, unloading the gearbox just long enough to allow the shift to go through. It has been claimed that shifter switches can save as much as 2/ioths of a second per lap.
This is small potatoes compared with full computer-controlled clutching and shifting, and it remains to be seen what effect Marelli’s system may have on lap times. Toyota has a similar system on at least one domestic car model, so it’s natural to wonder how soon we may see a similar setup on a production motorcycle.
Kevin Cameron
