OS Giken: OS STR Twin Plate Clutch

[Vaeth]

The OS STR clutch is marketed as being a fully circuit spec-ed twin plate clutch that still retains civility in terms of day to day driving and comfort. It can be bought for around AU$2000 new.

Feel
I have mixed feelings about the feel of the clutch. Don't get me wrong, the clutch provides excellent feed back. There is no doubt as to where the bite point/zone is, and the clutch feels smooth as stock, but what I mildly dislike about this clutch is the weight of the pedal.

This clutch feels lighter than stock. Whilst I needed to rely somewhat on my thigh muscles to work the stock clutch, this clutch can probably be worked with just your calf muscles. It might be simply a matter of getting used to it, but for the moment, I prefer the more hefty feel of the stock clutch.

Noise
From memory, I remembered (obviously incorrectly) that the OS STR was marketed as being a "quiet" twin plate clutch. This is not the case. Anytime the clutch is disengaged (clutch pedal down), there is a clinking/rattling sound. This is probably my biggest gripe about this clutch. I wanted my car to be 'civil', and this clinking sound isn't helping at all.

Drivability
Ok, this is where the OS STR clutch scores full points. I drive this clutch like I do a stock single plate. I slip it at the lights, I slope control with it, I parallel park up/down inclines with it, etc. There is no sudden "bite" that I was expecting with a twin plate clutch. Apart from the clinking noise, I wouldn't know I was driving with a twin plate clutch. I reckon an L-plater could drive this clutch.

Performance
As to whether it holds up when the engine is given a good kick, I don't know yet as I am still breaking in the engine. However, to quote my engine builder who did the first 100km of engine break in for me, "dont let the lightness fool you, it can grab quite well when you ask it to. The lightened fly wheel is very nice too. Rev matching is a breeze, and just generally revving the engine feels noticeably easier/willing now.

Others
OS Giken describes this clutch as being specced for circuit racing and yet comfortable for daily driving. They do not recommend this clutch for drag racing.

Score: 7.5 out of 10

--V

[Wangan_X]

so i take it it doesn't have a high torque capability...

[Vaeth]

I think it's more like it can't take the abuse that drag racing dishes out. It's holding capability is supposed to be at least as good as the OS Giken R2CD. But now I am moving into the realm of speculation and paper specifications.

--V