So exactly WHICH clutch plates are 190mm dia?
Turbo Mini Forums

I guess the other consideration is that less area will heat up quicker. So on a track you may overheat the plate if it doesn't have enough area.

It does seem odd that you can increase torque by increasing the ID. I understand you are increasing the average radius, but taken to its logical conclusion you end up with very little material. As Paul says there must be a point where the advantages of area verses radius cross.

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

Right here goes.

Say:

R = Effective Radius
A = Area of lining
TF = Tangential Force
CF = Clamping Force
T = Torque
Coef = Friction Coef

T = CF * (A/R) * Coef (lb ft = lb * (ft2/ft))

T = TF * R ( Lb ft = lb * ft)

So for a given torque:

TF * R = CF * (A/R) * Coef

TF = CF * (A/R2) * Coef

Hence for a given clamping force and friction coefficient the tangential force is proportional to the square of the effective radius.

So for a given torque, as you increase the effective radius the tangential force reduces proprtionally, but the stiction force reduces by the inverse of the square of the effective radius.

Does that make sense???

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

i think i should have paid more attention in maths...

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I feel an excel session coming on at work tomorow.... lol


Paul,

in,

TF = CF * (A/R2) * Coef

I take it you mean

TF= CF*(A/(R*R))* Coef?

Edited by Joe C on 9th Feb, 2009.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Paul,
You screwed 1 hour of my life last night trying to establish and undwerstand your thinking - and those equations LOL (I'm laughing now - but was confused as fudge last night).

I think the sectional aspects of ceramic it is more to do with allowable lining pressure, and the amount of material needed to simply 'do the job'. Also consider that a 'full compliment' surface of a metallic compound would be hugely heavy - and expensive.

The allowable pressure is what i find referenced in all the engineering books I found - nothing on area however.

Sorry Dave. Realised my balls-up as I got into bed and lay awake thinking about it for hours - Sad.

The theory that friction is dimensionless and that the contact area is irrellevant was developed by Coulomb in the late 1700s.

When you push the two metals to the limit of the adhesion allowable by the chemical bonding of the two surfaces all sorts of unexplainable things are going on.

Lets just forget about it and design for the full plate area.

Edited by Paul S on 10th Feb, 2009.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

ok, after writing that, I'm now questioning myself...

Is it more to do with the maximum area you can use to keep an 'acceptable' engagement, rather than a snatchy one as the friction goes up?

Imagine it was rubber lined with a co-eff of 1.0 or whatever - there genuinely would be no take-up whatsoever; it'd be simply a switch (assume a very rigid rubber).
Maybe that is more to do with it?

I'll shoot another email off to clutch fellow.

You may be right.

I think that the coorect term is kinetic friction. That is the science of sliding surfaces rather than static.

Under kinetic friction, the coefficient is variable.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Well, it's not purely kinetic is it - it's the transition of kinetic to static. The change between the two is something that I can't find any references to.

You're right that they never get close to the edge like we're eeking out - and trucks are so low geared that kinetic to static transition is not really an issue either.

I bet someday, someone will develop a proven relationship between coefficient, surface area and clamping force. Then there will be a formula to work it out.

The problem we face is static to kinetic. As boost comes on the clutch starts to slip.

It's the stress between the two materials that, as torque increases, causes slip. That stress is due to heat at the surface layers.

Hence, in my opinion the area plays a large factor.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I guess the fact is that with the current clutch set up that most of us run we manage to keep things together. But to the detriment of the thrusts. As I understand it (there is that phrase again) Dave's cluch will provide the same if not more clamping force, with less stress to the thrusts. Therefore most should be ok.

As paul says, just do it and test it with current plates available. I guess if the theory of average radius holds true you could design you own paddle with the same area but having the paddles much thicker at the top and thinner at the bottom, if you see what I mean.

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

Okay so my head is hurting! lol

Would there be any advantage in using a 190mm plate over a 180mm plate?

Im looking at the C-AHT594 190mm plate but not sure if it will be better or worse than the C-AHT596 180mm plate?

https://www.facebook.com/pages/Fusion-Fabri..._homepage_panel

www.fusionfabs.co.uk



1/4mile in 13.2sec @ 111 terminal on 15psi

yes matt ,any increase in dia of the driven plate increaes its torque capability .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

incidentaly i may have a supplier for relining the turbo plate to a .45 coeff lining kevlar/organic . if it works out ill see who wants one .looks like somewhere around 80 quid +pp running that through the equ gives a fiar bit more torque capacity for any type of clutch .
off you go joe .....excel !

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

I think we are now fast approaching another limit, grip! Testing soon with some new slicks, not the softest around, but some that will last 20 odd laps.

Team www.sheepspeed.com Racing

Cheers Robert, thought that was the case. So do both those plates have the same lining, because im sure most people use the 180mm plate? Could be wrong though?

Jim, the lack of grip was the reason I didn't know my clutch was slipping until I got it onto the rollers! The wheels spun way before clutch slip.

https://www.facebook.com/pages/Fusion-Fabri..._homepage_panel

www.fusionfabs.co.uk



1/4mile in 13.2sec @ 111 terminal on 15psi

The 190mm plates can't be used as a direct replacement on a pre-verto setup unless you modify the backplate i think.

I looked at the Jokespeed flywheel with a 190mm injection plate. The sprung center fitted snugly in the center of the pressure plate, a little too snug for my liking, and the friction surface overhung by a little on the outer radius on the flywheel but not he back plate.

It would fit without machining, but I cannot comment on one of the real ultralight flywheels from MED, Swiftune or Minispares.

So could be worthwhile to get a little extra out of the Pre-verto setup, with a bit of tweaking to the back plate!

https://www.facebook.com/pages/Fusion-Fabri..._homepage_panel

www.fusionfabs.co.uk



1/4mile in 13.2sec @ 111 terminal on 15psi