Clutch: Subaru WRX/Sti clutch FAQ

What is the most transmission friendly clutch? The OEM organic clutch is by far the easiest on your transmission. This is due to the lighter clamp loads of the OEM pressure plate and the organic clutch material. Organic materials, which are bound by resins, will almost always loose friction when they get very hot. This is because the resin melts and becomes almost like a lubricant rather than a bonding agent. Any increase in clamp load or clutch material coefficient of friction will increase the shock load to your gears.

Can I use a 6MT clutch in my 5MT? Yes, but it requires some modification to do so, this link provides detail on how to do so.

Can I use a 5MT clutch in my 6MT? Yes, but you do have to use the 6MT clutch fork.

So this gives me carte blanche to use either clutch willy-nilly then right? It means you CAN use them in either application, it doesn’t mean you SHOULD.

How much torque will the OEM 5MT and 6MT clutches hold? Though no one knows for sure, common knowledge say that the 5MT will hold 300 TQ and the 6 MT will hold 400 TQ.

What clutch will hold the most power? Generally speaking, one that has:
a. Highly sprung pressure plate. The more clamping force the pressure plate exerts, the better it will grip.
b. High coefficient of friction clutch material. The higher the coefficient of friction, the better it will grip.
c. Increase the amount of surfaces. This can be accomplished by going to a twin or triple disc design.

What about a “Stage 1 clutch“? Stage 1, 2, 3, etc. clutches are just a marketing tool like Stage 1, 2, 3, etc. power packages for Subarus. Some manufacturers have them, some don’t. While a staged clutch may suit your application, DO NOT use a staged clutch package as a methodology to purchase your clutch based on your staged Subaru.

Where do I buy a clutch? Well here are some links for various clutches for our Subaru WRX/STi’s.

Competition Clutch 15030-STOCK 04-11 Subaru STI Stock Clutch OEM Kit

Competition Clutch 2004-2011 Subaru STI Stage 2 – Steelback Brass Plus Clutch Kit

Competition Clutch 2004-2011 Subaru STI Stage 3 – Segmented Ceramic Clutch Kit

EXEDY 15803HD Racing Clutch Kit

Competition Clutch 2002-2005 Subaru WRX Stage 2 – Steelback Brass Plus Clutch Kit

How hard is it to install a clutch? Allow around five hours for install time. Professional installation, depending on your area, is around $300. This is one vehicle modification that should be farmed out to a professional unless you have the right tools/equipment and are mechanically skilled.