DIY centrifugal clutch for a Lada
centrifugal clutch F1 technical net
A sprag (clutch) is a 'one way' clutch that only allows drive in one rotational direction and freewheels in the other.
In Borg Warner automatic gearboxes you can easily instal the 'sprag' the wrong way round and lock the entire unit.
If the sprag is between the engine and the gearbox there would be no over run braking but changing manual gears would be easy if the throttle is lifted.
The unit pictured by flynfrog certainly looks like it has two clutches, one cetrifugal and one multi plated.
What unit is it?
What would happen if you connected a centrifugal clutch to a freewheel in the order:
engine -> centrifugal clutch -> freewheel -> gears and wheels?
This would eliminate the need for a second manual clutch, since breaking the connection between the engine and the gears could be done at the freewheel instead of the centrifugal clutch.
Changing into higher gears would need you to let the revs drop a long way before changing (engaging the freewheel at the same time as engaging gears could be messy?) But changing down would just require a bit less gas before the freewheel did its job?
Have I got this right? Has anyone actually done this?
EDIT: Just looked what a sprag is.. In the diagram, and according to what Flynfrog said, this works completely opposite to what I described.. It's an unfreewheel...
In Borg Warner automatic gearboxes you can easily instal the 'sprag' the wrong way round and lock the entire unit.
If the sprag is between the engine and the gearbox there would be no over run braking but changing manual gears would be easy if the throttle is lifted.
The unit pictured by flynfrog certainly looks like it has two clutches, one cetrifugal and one multi plated.
What unit is it?
What would happen if you connected a centrifugal clutch to a freewheel in the order:
engine -> centrifugal clutch -> freewheel -> gears and wheels?
This would eliminate the need for a second manual clutch, since breaking the connection between the engine and the gears could be done at the freewheel instead of the centrifugal clutch.
Changing into higher gears would need you to let the revs drop a long way before changing (engaging the freewheel at the same time as engaging gears could be messy?) But changing down would just require a bit less gas before the freewheel did its job?
Have I got this right? Has anyone actually done this?
EDIT: Just looked what a sprag is.. In the diagram, and according to what Flynfrog said, this works completely opposite to what I described.. It's an unfreewheel...
When you pull the shift lever it activates the plate clutch allowing you to change gears.
They are usually on less performance models where the rider is likely to be less experienced and doesn't want to use the hand clutch
They are usually on less performance models where the rider is likely to be less experienced and doesn't want to use the hand clutch
An unusual feature of the Saab drivetrain was a 'freewheel' (overrunning clutch). This allowed the transmission to run faster than the engine, such as when decelerating, or descending a long hill. Although such freewheels had been provided in other cars before as an economy measure,[8] they were required in the Saab because of the limited lubrication in the two-stroke engine. A petroil-lubricated two-stroke requires lubrication according to its speed, but provides this lubrication according to the amount of its throttle opening. Where the engine operates at high RPM and low throttle (such as when coasting down a long hill), the lubrication provided may be inadequate. With the freewheel, a coasting engine could reduce its speed to idling, thus requiring only the small lubrication available from the closed, coasting, throttle. In certain higher-performance models and in later two-stroke models, direct injection of oil into the engine from a separate reservoir allowed lubrication to be a function of engine RPM and rendered mixing of oil with gasoline unnecessary.[9]
Freewheeling was retained in the four-stroke variant, until the end of production and in the Saab 99 with the 1709 cc Triumph engine. A minor drawback to the freewheel, particularly for drivers unfamiliar with the Saab, is that it makes engine braking unavailable although it could be manually engaged or disengaged by a control in the foot-well. Fixed wheel engagement, using the foot, could be difficult, as it involved pulling a 'T handle' intended for manual operation
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