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The moment a clutch begins to engage...

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Old 03-05-2015, 08:59 AM
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There is a huge difference to feel with a tailing or leading mount of the fly weights. With leading the clutch will be more agressive. A clutch wil also be more agressive when a strong spring is mounted and a a larger gap is used.
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Old 03-08-2015, 06:56 AM
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Originally Posted by Geezatec View Post
Maybe a factor. Centex style clutches just have to think of centrifugal force. The lighter of weight of clutch shoes the earlier it engages and strength it engages. You can physically see it on test bench when breaking in your engine. Average folks 1/3 of throttle is start to engage. I like to see it engage as soon as possible when you crack the throttle. The more rpm, the aggressive it is. All come down the style of driving. Everyone is different. Diagnosis of wear parts tell you, dust, glazing, cracks(lack of friction), should tell you whats happening.
Just got back from an interstate event will compose my thoughts and compile the additions in the morning. Cheers to all those contributing to the discussion.
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Old 03-09-2015, 04:04 PM
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Originally Posted by Roelof View Post
There is a huge difference to feel with a tailing or leading mount of the fly weights. With leading the clutch will be more agressive. A clutch wil also be more agressive when a strong spring is mounted and a a larger gap is used.
Roelof, so I've heard springs are linear, so the larger the gap I'm assuming the shoe accelerates faster and hits the bell harder at the point of engagement?
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Old 03-09-2015, 04:15 PM
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Originally Posted by Geezatec View Post
Maybe a factor. Centex style clutches just have to think of centrifugal force. The lighter of weight of clutch shoes the earlier it engages and strength it engages. You can physically see it on test bench when breaking in your engine. Average folks 1/3 of throttle is start to engage. I like to see it engage as soon as possible when you crack the throttle. The more rpm, the aggressive it is. All come down the style of driving. Everyone is different. Diagnosis of wear parts tell you, dust, glazing, cracks(lack of friction), should tell you whats happening.
Please confirm this for me geezatec. The light the shoe? or the lighter the fly weights/throws? If THROWS are lighter it takes more RPM to throw the shoe, so Im a confused by how this would throw the shoe earlier.

I also check the stretching of the shoe holes, I assume they bite too hard at too high RPM and deform them. Would like to know what you think causes the glazing versus the dusting. Im assuming, that glazing would be caused by slip and dusting by too high RPM engagement and aggressive throw on a softer shoe.
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Old 03-10-2015, 01:46 AM
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I've found that my friends clutch settings slip for me, he runs exactly the same clutch as me but I run 0.3mm less preload on the spring, if I run as much preload as he does I will dust the shoe, I think driving style has a lot to do with clutch setup.
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Old 03-10-2015, 02:24 AM
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Originally Posted by JamesHealey View Post
I've found that my friends clutch settings slip for me, he runs exactly the same clutch as me but I run 0.3mm less preload on the spring, if I run as much preload as he does I will dust the shoe, I think driving style has a lot to do with clutch setup.
This is where it all goes blurry for me too. Factoring in the engine tune, the age and retention of the spring and the amount of shoe wear.

Do you think that the extra preload slips the clutch into dusting or the engine enters more of a power band that is too aggressive for the shoe and setup?
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Old 03-10-2015, 02:49 AM
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Originally Posted by blis View Post
Roelof, so I've heard springs are linear, so the larger the gap I'm assuming the shoe accelerates faster and hits the bell harder at the point of engagement?
the flyweights are further out then, so they have more force to push the clutch shoe against the clutch bell.
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Old 03-10-2015, 02:50 AM
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Originally Posted by JamesHealey View Post
I've found that my friends clutch settings slip for me, he runs exactly the same clutch as me but I run 0.3mm less preload on the spring, if I run as much preload as he does I will dust the shoe, I think driving style has a lot to do with clutch setup.
You drive also electric cars, and your friend doesn't?
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Old 03-10-2015, 04:03 AM
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Originally Posted by M7H View Post
the flyweights are further out then, so they have more force to push the clutch shoe against the clutch bell.
Interesting hypothesis...



So to keep it simple, V = 4 and r = 2

a = 16 / 2

Then if we maintain same velocity... V = 4 and increase radius to 3

a = 16 / 3

Where Mass x Acceleration = force, the acceleration decreased as the radius grew.

Thanks for the food for thought, but I am confused by this hypothesis... the mass of the throws do not change either and assuming the ramp is the same.

http://en.wikipedia.org/wiki/Centrifugal_force

What is good about this finding is that the velocity must increase as the gap is larger, hence the engine is revving higher in order to compress the spring. The spring is a linear force which means the shoe actually slows down but the acceleration of the free engine increases the velocity of the throws to overcome it. So engine tune, pipe, manifold and power band have a great deal to do with the setup of a clutch. And they say I think too much, in fact I'm ignorant and thanks again for the food for thought!


PLEASE correct if I am wrong.

h

Last edited by blis; 03-10-2015 at 04:23 AM.
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Old 03-10-2015, 05:20 AM
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Originally Posted by blis View Post
Interesting hypothesis...



So to keep it simple, V = 4 and r = 2

a = 16 / 2

Then if we maintain same velocity... V = 4 and increase radius to 3

a = 16 / 3

Where Mass x Acceleration = force, the acceleration decreased as the radius grew.

PLEASE correct if I am wrong.
Yep, you are wrong.
You are forgetting, that the speed "v" doesn't stay constant, but also increases.
And the radius "r" can not increase anymore, once the shoe hits the bell.
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Old 03-10-2015, 07:00 AM
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I still don't understand. The formula states that the tighter the radius, the greater the force because it's mass times acceleration. So the force of the throws reduce the further out of radius is, this is governed by the gap. The force depends on the weight of the throw and the radius. So the forces are stronger on the throws the shorter the radius. The velocity is also governed by the spring, not the gap. Can you clarify where I am incorrect before adding this to the first post.
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Old 03-10-2015, 09:58 AM
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This formula is only for centrifugal forces. But we are talking also about axial forces, so you can not use this formula for that I believe.
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Old 03-10-2015, 04:33 PM
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Now the track/forum hero`s stay quiet, right Martin..?.lol..

You guys are on the right track, the formula can be used, it`s simple mechanics/dynamics.

In the formula for centripetal acceleration, we need to use the opposite reaction acceleration called the centrifugal acceleration. Multiply with the mass and we have a centrifugal force, seen in the picture in red arrow.

The speed in the formula is the tangential speed shown with v in the picture, so if we have a bigger radius of rotation of a infinte small piece of mass, we automaticly have a higher tangential speed of this piece of mass.

If we place the picture on the clutch we can understand the parameters

So, a higher centrifugal force.

This force is converted by the angle in the flywheel to a axial clutch force, in the clutch the radius and speed are related, a bigger gap means a hogher axial force, means a shorter slip time.

The spring works against the axial force and is used to control slip time.

Thats it..
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Last edited by rbakker; 03-10-2015 at 04:47 PM.
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Old 03-10-2015, 04:39 PM
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Originally Posted by M7H View Post
You think to much.....
You need to think a little bit more....lol...

Tomorrow we drink a beer at 18.00 Martin..!!
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Old 03-10-2015, 04:51 PM
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Originally Posted by rbakker View Post
You need to think a little bit more....lol...

Tomorrow we drink a beer at 18.00 Martin..!!
Yes we will!
That's to much for me Roy.
Beer. That i can understand!

Don't forget, i only finished elementary school!
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