The spec twin is best twin clutch for your needs. It got bad rap form some over critical enthusiasts. I drove RYUEVOIX car when he was bad mouthing the clutch. The clutch drove as near to stock as you will get for a twin. very smooth very quiet. Chris was only upset cause he couldnt grab the high RPM shifts like exedy he took out. Spec promised the clutch would shift great or they would refund him. Well that never happen. I can assure you the clutch is awesome. its built like a tank. TedB has one in his car and loves it. Its perfect for fast spooling setups that dont need to rev to the moon to make power.

 

Strapped center plate will be quiet. But it does create another problem. The plate does not float. So it will usually drag on one of the plates. This means that one plate will wear faster than the other. Also means it may not shift great if dragging gets severe enough. I had a custom twin in my mirage when it was first built. It had a strapped center plate. It had the above mentioned problems.

 

http://www.tamparacing.com/forums/mi...ce-clutch.html

picture 10 shows the mid plate is a floater design. but since the PP legs are aluminum the floater is very quiet. the aluminum absorbs most the rattle. the PP is strapped. which is not any kind of disengagement issue. the strapped center plate like the fidanza in post one is what is a problem. the center plate needs to be centered between the plates during disengagement. The straps hold the plate in one spot. When clutch is new it will be in correct spot. But as plates wear it will drag on one plate more than the other. the thinner the plates get the worse the dragging gets.

 

The issue I saw on the Spec clutch was input shaft wear, lending me to believe that the discs that ride the splines weren't machined to a tight enough tolerance. That's why I was leaning away from the Spec.

Other than those couple people though, everyone else seems to love them, including Ted B, as you mentioned. That was the clutch for me until I saw a couple of those threads pop up with the shaft wear.

Edit: Here's the Spec thread that I was talking about.

 

In your custom clutch, was the strap also a spring like strap...where the floater would be pushed away a bit when not under load? I understand what you're saying about the chance of one plate to wear faster, but if there is separation when the cluth pedal is depressed (from the springed strap), wouldnt' that resolve that issue...or are you saying the issue still remains even with the springed strap?

 

This sort of goes with my question above...if the strap is a sping also, it's not really holding the floater in one spot...it moves when the clutch is disengaged.

I can't really tell from those pics what's what. Maybe my inexperience with twins. It looks like 3 clutch discs...I don't see a floater? Isn't picture #6 in the thread I linked to above the floater plate? And I'm not sure why they are strapping the PP other than a smoother engagement?

 

SPEC is complete garbage... I've got plenty of first hand experience in that department.

https://www.evolutionm.net/forums/se...ec-clutch.html

They do have a strapped floater but the clutch is poorly designed. It literally ate 2 brand spanking new input shafts. If you enjoy doing rebuilds then go with spec. My Exedy is actually very quiet... but this isn't the case for everyone. I have only seen one car in person with the OS Giken and it was as quiet as stock.

My .02

 

pic 6 is the floater plate.

the metal straps that hold a floater plate are not a good idea. these straps are very stiff. they act like springs went they are side loaded. meaning if you push the floater plate side to side the spring straps will center it back up. with pretty good force. ideally the plate needs to be perfectly centered between the two clutch disc during clutch disengagement. there is only about .020 air gap available and maybe less when the pp is pushed. this leaves about .010 on both sides of the center plate. for the clutch plates to float freely (required for good shifting)

when clutch is new it will be centered very nicely. but when clutch plates are used. it only takes .005 wear of each plate before the pp is now positioned .010 from its original new position. so when the clutch is now depressed. there will be .010 on both sides of one disc. the second will have none. it will be dragging slightly on the floater. the spring straps have no way to compensate for disc wear. when the discs wear another .010. the second disc will now have the drag of the spring pressure of the straps depressed that same .010.

a picture would be very helpful here. but i think my text makes it clear.