I wanted share some info here for Legacy GT and Spec B owners. I have been doing lots of research into the clutch that will be going into my 2008 LGT Spec B (450/wtq or 380/wtq on E85) depending on which Mustang dyno and how it is calibrated.
Also, i'm looking at future power enhancement when I need to replace/rebuild/renew the block, so the clutch will need to be able take the increase if necessary, as I may change the turbo too.
I originally was looking at Exedy Twin Plate HD, and was almost ready to get one, then heard about the RPS Max Street clutch, but then trying to find one was another issue, then I kept going back and forth between this and the Exedy Twin-Plate (pricewise, RPS is cheaper and holds just a much drivability is smooth, etc.). So I decided to wait and keep researching.
I am looking for a clutch that can hold and deliver the power, feel close to stock pressure, yet still retain daily drivability, PP and friction material needs to last and take abuse of the occassional track/strip hard launches and FFS, should be able to rebuild it if necessary, and finally, be affordable, and competitively priced from a reputable company. I know, it's a lot to ask...
I believe I have found that clutch that meets the requirements, but I want to talk about what I found out. I was looking at the Carbonetic (ATS/Across) carbon blade, but it seems that the only rebuilding part is the disc itself, and there is not carbon friction material on the PP or FW which is what carbon needs to react to limit the wear on the carbon disc. So, the Carbonetic carbon blade is not a true carbon/carbon clutch.
I looked into the RPS clutch and this seems to meet all the requirements. I contacted turboclutch.com (RPS), spoke to RJ Smith (son of the company) and he told me that they are now making and marketing the RPS single and dual carbon/carbon clutches under a different name. Some may have heard, but this was news to me.
When I inquired about the RPS Max Street, he mentioned the single carbon/carbon clutch.
"Another option that we have is a Single disc Carbon-Carbon clutch with a steel flywheel. This unit has a total weight of 32 lbs vs the 36 lbs of the factory unit. With the 32 lbs you will not have a miss fire code and the gear noise will be minimal vs other steel flywheel options. This clutch is rated for 600 ft/lbs and still has a stock like pedal feel. The nature of Carbon-Carbon is very smooth like the factory clutch. This clutch lists for $1,495.00..."
So, I asked for some additional info. and got it:
"Our Single carbon is built around the factory stamped PP. We replace the diaphragm spring with our Patented Heat Treated(HT) one and replace the cast steel pressure plate ring with a Billet Aluminum one. This ups the clamp load and removes 3-4 lbs from the pressure plate. Even with the HT diaphragm we still only have a 10% pedal increase. As Carbon-Carbon has to rub against itself we have it in the pressure plate and the flywheel. Both are screwed in making it easy to rebuild by you, the customer, if need be. We offer both a Alum flywheel or Steel flywheel option. The Steel flywheel is recommended for all street cars with factory ECU's as it weighs 32 lbs, which will not throw a miss fire code.
These clutches are being sold under the name SpeedSport Clutches. Our website is www.SpeedSportClutches.com
and it is still having all the content updated."
As I found out, looks like they have offered this clutch for other popular vehicle/engines too, such as, WRX, BRZ/FRS, Mazdas, EVO, and Nissan 350Zs, SR20 and KA24DE.
Clutch cover for BRZ/FRS showing the carbon riveted to the aluminum billet PP face.
Flywheel side for the STi 6 speed.
5/22 - Update. Received the carbon-carbon single disc clutch kit for a 6-speed (Spec.B or STi).
Removed the cover to expose the rest of the clutch. Weight with the fully assembled clutch with T.O. bearing is a shade over 33 lbs.