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Discussion Starter #1 (Edited)
I've noticed that someone must have inspected this friction plate and marked these cracks, I did not at first noticed them. Can someone please tell me if I can still install this or junk it. I am sitting idling and cant make up my mind if to buy a new one - my budget is long time spend allready.

also can someone maybe explain the 'Q' mark made on the other side - is this usefull at all? - can't make out what was written there???
 

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Discussion Starter #2
Yea-or-Nea

:)go or no go?:mad:
 

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do you really need a 4 puck clutch disk? the stock one take quite a bit of abuse befroe it gives up.. the cars here at sears point raceway use stock clutch disk for there racing, no problems..
 

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Discussion Starter #5
No preference really - I bought the whole racing clutch flywheel with this 4 puck clutch. I really just need to get my car on the track now. I'll see how this one goes and then make up my mind how I like it or not
 

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i was thinking there is more ' area' on a reg. friction disk.. perhaps a stronger pressure plate would work better with a stock disk..
 

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poor construction

We have our own clutch discs manufactured in USA. Lots of foreign stuff out there. The redest flag on your disc is that the rectangtular windows for the springs have no stress relief holes drilled at the corners. A few years ago, this happened and we replaced a number of discs when the windows cracked and the springs came popping out. We have a four puck race sprung disc and two full faced discs suitable for street or race, one organic and one kevlar material.
Since our BB ads for November are not up for some reason,please look on spruellmotorsport.com. Best regards, Paul
 

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Richard Jemison
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Race disk

i was thinking there is more ' area' on a reg. friction disk.. perhaps a stronger pressure plate would work better with a stock disk..
__________________
Torque capability is a function of clamping force and the friction materials coefficient of friction.
If the clamping force is full circle and the friction material is full circle, then you are dependant on nothing but the materials slip resistance in transfering torque. Using smaller 4 puck clutches concentrate clamping force to a reduced area which puts greater pressure per sq inch on that material. Hence more tq capability if the material is not too slipery...
Common organic clutch material has the best grip, better than metalics and much better than kevlar, or carbon fiber..
However the issue with materials is also one of weight. Metalic 4 puck pads are much heavier than organic material, this is a drawback for race clutches. Additionally the "torque" spring center type of (stock) driven disk are very heavy. The driven disk is the largest issue for the syncros to deal with. The lighter the clutch disk the easier for the syncros to do their job. As well the wafer springs in stock type disk that allow compression of the lining material for smooth engagement (for women drivers) are detrimental to syncros particularly in race applications where shifting is hurried.
The best disk for racing are solid center (no springs) with common organic material (lighter than metalic pucs) bonded directly to the center material with no give under pressure or release for crisp release of the disk..Commercially they are available with steel centers.

Thats why I was building solid 7075 alloy aluminum center disk for my racer buddies. See pic below. These are 1/3 the weight of a stock alfa 81/2" inch disk
 

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As well the wafer springs in stock type disk that allow compression of the lining material for smooth engagement (for women drivers) are detrimental to syncros particularly in race applications where shifting is hurried.
I have one of Richard's plain friction discs in my Spider and my wife has no problems with it.
 

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Sachs makes a pressure plate and disc for the Porche 911 that fits and is plenty strong for racing use. Used this approach for a few decades....

Robert
 

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The Porsche PP works but the Porsche disc has different spines. We have these pressure plates and a selection of discs. This has become the 215mm clutch set up of choice for our customers.
 

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Thanks Paul. I knew the PP was correct, but forgot about the disc. It's been a while; the set I have came from John Shankle! This has been a favorite race set-up since the 2L's arrived in the 70's. Slightly elevated foot pressure to release, but release and engagement are very clean and sharp. Foot pressure is a little heavy for 1600 converted bell housing with cable release, but still streetable. Especially nice with a lightened flywheel.


Robert
 

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I have one of the alum 911 pressure plates; was used in a 115 Alfa but has straight fingers on the diaphragm with non-raised curved part at the center for the Alfa TO bearing to strike properly, so the TO bearing hit about a half inch upward. Doesn't look like it hurt it though.
Happy to sell if someone wants it. I'm told you can alter the Alfa TO bearing to strike the straight fingers properly.
Andrew
 
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