Did you ever wonder
why a 50cc motocrosser has beefier transmission
gears than a typical 450F? Why does a typical
seven year-old break more chains in a year than
a seasoned pro? Do you feel that you spend more
time and money on items such as clutch baskets
and primary gears than you think you should? Well,
at Cobra we have asked the same questions, and
with our patent pending Cobra Friction Drive (CFD),
we’ve done something about it!
The Cobra Friction Drive is one of the most
innovative pieces of technology to come
around in 50cc racing since Cobra first
introduced the modern 3-shoe clutch a
decade ago. Its operating principal is
simple: The CFD adds some ‘give’
to the driveline system. Unlike any other
type of motorcycle transmission, when
a centrifugal clutch (used on all 50cc
motocrossers) is locked up, the entire
powertrain…everything from the rear
wheel to the crankshaft…is also
locked. Now imagine landing off a big
jump with the throttle pinned. The engine
is spinning at close to 15,000rpm, and
then SLAM, the rear wheel comes to almost
a dead stop as it hits the ground. With
very little give in the system, this results
in brutal wear and tear on many components
such as the crankshaft, clutch basket,
clutch shoes, transmission gears, transmission
bearings, chain, sprockets, and rear wheel.
It’s no coincidence that many of
the items that you replace and repair
often are on the aforementioned list.
So how does the CFD
work? It’s very simple, actually.
The primary gear, instead of being one
solid part, has been replaced by a clutch
that is set to disengage at a pre-determined
torque level. This break-away torque is
several times the maximum engine torque
(so it never slips when the engine is
driving it), however, when it receives
a high load in the other direction it
spins providing a cushioning effect on
many expensive engine and driveline components.
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