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

Is it just the verto (sprung centre) plates? Do any of the AP race/Rally organic or metallic plates measure over 180mm diameter?

I'm basically at a point that I can take a whole lot of intertia from my clutch design folowing my analysis over the weekend, if I eliminate the 190mm capability - but don't want to do so if it'll screw things up later on...

Let us know!

Yes there are 2 plates that i know of thar are 190mm,

the C-aht594 rally plate,
and a 4 paddle one.

C-AHT594, C-AHT600 and GCP90832AF

Cheers all.

Looks like I needn't stick to 190mm - diameters are well stated and defined. I was juast concewrned if there was a 'vagueness' on the diameters - like a part number could be 179.8mm or 190.2 depending on what supplier name was on it ffor example...

Cheers!

I reckon the best plate is the C-AHT597 5 finger sintered jobbie. Mine measures 180mm.

With so many 180mm options, why compromise your design.

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."

My thoughts exactly Paul. Now I need to figure out what the effective "ID" of the friction lining(s) on the C-AHT597 is.. Anyone got one to hand and a measurig stick - or maybe MiniSpares Gavin can help?

the c-aht 594 i have here is 134.5mm ID

ooh, you star!

Whilst you're on - is the OD spot on 180 - or is it like 180.5 or maybe 179.2?

As an aside - I've just knocked this up. It puts everything in the one place and should serve as a useful reference.

http://www.davecoxon.co.uk/Mini_180mm_190m...utch_Plates.pdf

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."

Unfortunatly my verniers don't go that big, but using a ruller it looks to be bang on 189mm OD

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."

Cheers guys. This place is like woolies - if you can't find it - just ask!

So looks like if I accept a 182mm max OD, and a 106mm min ID, I'll have a little room for misalignment / clearance and be good to go.

Glad I asked about the ID as I was basing my design on the 132mm (approx) ID of the AP race/rally plate!

Although it is interesting to think that if you machined the C-AHT597 to a 130mm ID, the torque capacity would increase as the effective diameter had increased...

Hmmmmmm......

lol true,

but yu can do it with sums

Yes i moved to the darkside

Instagram @jdm_brett

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."

But how relevant is contact area in a static state (ie clutch locked)? Friction is dimensionless after all. I am convinced it does vary in a dynamic state (ie clutch re-engaging), but don't know how.

BUT - I've just sent an email to my friend in the Eaton Clutch division who will no doubt answer all these questions, so I'll report back with his answers.

Edited by TurboDave16V on 9th Feb, 2009.

Dave mini13 said it was 189mm

Yes he did - but he has got the 190mm unit - which I am going to design out of the equation...

ok cool i missunderstood

Well, it seems that clutch designers don't really do anythign special - unlike the designers of brakes for example... In short, it is all considered static, hence the mean radius is the most important factor - I really didn't learn much I didn't think of already.

Which kind of made me more confused the more I looked at the minispares c-AHT597 plate with its pentagonal ID shape.

Of course, the pentagonal shape is not a true circle therefore - I guess an equivalent internal DIAMETER would be in the region of 113mm...

Even using this number, I can't think if any reason why you wouldn't machine away the pads to a 130mm diameter (or whatever felt right with respect to leaving 'meat' around the rivets), as this will always increase torque capacity by applying the (same) clamping force over a greater effective radius.

A quick calc shows that the difference between 113mm ID and 130mm ID is circa 13Nm increase in capacity?

Someone argue with me - it can't be this simple - can it???

Edited by TurboDave16V on 9th Feb, 2009.

Reduced surface area = greater wear rates ??? (obviously on engagement only)

Friction might be dimensionless, but wear rates aren't.

Schrödinger's cat - so which one am I ???

Very true - but when you're spending your weekend at Avon launching the crap out of your car to win the big one, are you really concerned about wear - or more concerned about being able to get your curlywurlies onto the ashphalt?

You are basing your theory on the assumption that the effective radius times the static pressure is the only criteria. The static pressure being the clamping force divided by the area of the lining.

So if you increase the radius or reduce the lining area you improve the clutch. This assumes a linear relationship.

There must be a area/radius relationship that is optimal, each side of which you do not achieve the torque capacity.

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."

Why should there be any difference? Think about a brake disc for just a moment; a 1mm square pad acting at (say) 100mm radius will create less holding torque than the same area pad at 150mm radius.

The area has remained the same, but the effect of changing the radius is significant.

Changing the area is indeed something I do not know the numbers for in this example, but I do know that a larger area means the same force is being applied over a larger area, which is shared over the area larger, and the area smaller than the true mean.

I can't see how 'moving' (note-not 'removing') the pressure from the smaller radius to instead act over the larger radius can be anything but advantageous?

Edited by TurboDave16V on 9th Feb, 2009.

This is where stiction comes into play.

There must be a torque for a given area/radius at which it will slip.

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."