Help a newbie understand: The difference's in clutches

Koenigturbo

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Oct 4, 2006
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Help me understand why a puck clutch is better than conventional clutch.
I would think the more clutch to flywheel contact would be better. Rather than a puck style that has less contact area. :1zhelp:

I'm running a Center Force clutch the kind with the centrifical wieght's

I'm not asking which clutch I should use.
 

Supracentral

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Mar 30, 2005
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Puck clutches are typically solid hubs because strength is the primary concern and smooth clutch engagement is not a factor. They are designed for racing use, remember that. They tend to clamp faster and harder due to the design. On the street they typically have lower lifespan and act like an on/off switch and are hard (nearly impossible) to slip. They tend to chatter as well. I drove an unsprung puck clutch on my old T66 MKIV - there were times where it was a real pain in the ass. However on the road course, the faster shifts and harder engagement makes for lower lap times.

Full face clutches are typically sprung hub (i.e. - the clutch uses springs in the center splined hub and a marcel spring between the plates to help make clutch engagement smoother.) On the street they typically have longer lifespans, are easy to slip and are more forgiving to being overheated. A sprung hub clutch with a full face disc will give the smoothest clutch engagement and will provide easy driveability. The only risk is that at high horsepower levels with aggressive shifting, you may break a spring, which is why puck clutches don't have them.

It's generally a trade off - the less streetable it is, the more power it will hold.

The exception is the RPS Carbon-Carbon Triple Disc - it drives like a stock clutch, will hold 1,200 RWHP and will last for a very long time. The reason is the triple carbon discs triple the friction surface area. This has the effect of tripling the torque rating with the same clamp load. This clutch feels like a 400 RWHP clutch but holds 1,200.

But there's a tradeoff with this clutch too - when I bought mine it was well over $3000...

Does that answer what you were wanting to know?
 

Poodles

I play with fire
Jul 22, 2006
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Puck clutches work because they increase the PSI on the friction material. Same force from the pressure plate, but less surface area = more pounds per square inch so it grips better.

Sprung hubs reduce the shock loads to the drivetrain. Marcel springs are what smooth engadgement (it's between the front and back layer of the clutch material, I have yet to see a puck clutch have these).
 

Koenigturbo

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Oct 4, 2006
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Well, that answers my qeustion,.. many thanks guys!!

From what I learned just now: the springs that are on the hub controls or dampens torsional force and the Marcel springs control engagement. Also now, understand about the "increased P.S.I. on the friction material".
Yeah, that's what I tought, that the puck style is for Racing, The puck style seems to be the choice here on S.M.,that's why I was confused I thought there was a street style puck clutch, that I wasn't aware of. Now I'm learning...:icon_bigg
 

Keros

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Mar 16, 2007
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Thanks Mike for posting that up.

Since we're asking n00b questions; I have seen several people talk about clutch straps, and breaking them.

What is a clutch strap?
Why did they break them? (and was it the driver's fault or the clutch's fault)?
If they break, why bother having them?
Do all clutches have them?
What advanteges do they have over the alternatives?
 

Supracentral

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Mar 30, 2005
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Koenigturbo;1424376 said:
Well, that answers my qeustion,.. many thanks guys!!

Glad to help.

Koenigturbo;1424376 said:
From what I learned just now: the springs that are on the hub controls or dampens torsional force and the Marcel springs control engagement. Also now, understand about the "increased P.S.I. on the friction material".

You've got it.

Koenigturbo;1424376 said:
Yeah, that's what I tought, that the puck style is for Racing, The puck style seems to be the choice here on S.M.,that's why I was confused I thought there was a street style puck clutch, that I wasn't aware of. Now I'm learning...:icon_bigg

There are a lot of people who use racing clutches on the street. If you're making really big horsepower, sometimes it's the only option. But your driveablity suffers greatly unless you go down the very expensive clutch route.

Keros;1424384 said:
Since we're asking n00b questions; I have seen several people talk about clutch straps, and breaking them.

What is a clutch strap?

I believe they are talking about the pieces that hold the clutch cover and pressure plate together so that they rotate together.

Keros;1424384 said:
Why did they break them? (and was it the driver's fault or the clutch's fault)?

No way to really tell. Usually it's via bad driver technique. i.e. - abuse (popping the clutch)

One other oddball possibly is not running a harmonic balancer.

I had a customer who kept destroying OS Giken triple disc clutches (a ludicrously expensive clutch) in his MKIV - they all failed the same, the cover separated from the pressure plate. OS Giken warrantied two of them, then told us that it had to be something on our end.

In the end we diagnosed it down to the fact he was running a lightweight flywheel and no harmonic balancer - it was literally shaking the clutch apart. (Damned thing revved like a Formula One motor however...) The car was seriously built, and had an insanely high redline.

Keros;1424384 said:
If they break, why bother having them? Do all clutches have them? What advantages do they have over the alternatives?

If it's the parts I'm thinking of, it's a required part of the clutch design that you really can't do without.
 

Poodles

I play with fire
Jul 22, 2006
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There is the clutch cover, the diaphram spring, and the friction surface. The friction surface is floating and moves in and out with pressure from the diaphram spring. The clutch straps are what allow it to float without binding. A sliding shaft would work, but it would bind from the loads more than likely, which is probably why it's not used.
 

Supracentral

Active Member
Mar 30, 2005
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Cz.;1424691 said:
ACT makes a 6-puck clutch that is sprung, FYI.

That's why I said "typically". You lose a lot of the benefits of a true race clutch by adding a sprung hub.