Originally Posted by
jtrmx250
All I know is that my RX8 shoes used to dust no matter what I did...why?...who cares?
I've got a serpent now and the clutch is worry free.
I'm enjoying this tread but reading it makes me aware of my limited knowledge of most things RC.....so much to learn
Hey Brian, have you ever seen Tim drilling holes in his throws to lighten them? So if the forces on the clutch plate are too harsh because the flyweights are too heavy and the shoe too soft, the "moment it engages" there won't be slip at all and a sudden gripping of the bell may graze the surface of the shoe. This is the whole point of this thread. The get a better understanding of the variables involved in engaging a clutch correctly.
Sure many factors will apply, as mentioned the engine tune, power band, engagement point and type of track. At a smaller track with tight corners, the inertia required to move the weight of the car on a stop start track may be too harsh.
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Back to the task at hand...
I think I've come to the conclusion that the weight of the throw and the hardness of the spring or tension applied with preload has more to do with the acceleration of the clutch shoe than the amount of gap. The amount of gap as RBakker said has to do with the forces being applied by the spring to cause slippage. How to measure the differences in forces applied and tension in the spring is my next quest and I'll likely need more help from those of you who like the physics as much as the performance.
This is because the radius change in the throw is negligable and even a 1mm gap will only change the distance on a 30mm clutch (hence velocity) from 94.25 mm per revolution, to 97.38mm per revolution an that's only a change of around 3%. So while the forces do change slightly, they arent significant.
So here goes, I need you keeping check on this RBakker!!
1g throw, 30mm clutch, 10k rpm engage (for one throw only)
At 10k/rpm the velocity of the throws are prior to engagement:
94.25mm * 10,000 / 60 = 15707.96 mm/s or 15.7 m/s
97.38mm * 10,000 / 60 = 16231.56 mm/s or 16.2 m/s
Centrifugal force calcs
15.7^2/.015 * 1g = 16432.6
16.2^2/.0155 * 1g = 16931.6
Again a 3% increase in force.
Increasing centrifugal force.
A Grub screw, a large one may weigh .2 grams. this is a significant factor of up to 20% more force!