Today I replaced my former ACT Street clutch (it begun to slip at 7000 miles - but it was used for drag racing) with a Sachs Performance 4-puck sintered clutch disc and cover. This clutch is rated at 670Nm (500lb-ft) at the flywheel but I ordered the further reinforced clutch plate (more pedal pressure) which upgrades the rating to 770-800Nm (570-590lb-ft) at the flywheel. I managed to get the clutch kit at reseller price (430EUR excluding VAT). I also used a new OEM flywheel, but my former flywheel was in good shape.
I realized that using an organic clutch for hard driving and especially drag racing is a nonsense. Especially with the ACT Street, it seems that the pressure plate springs cannot cope with repeated extreme heat and the pedal becomes a bit soft after 5-6 launches in a row (it hardens again after the clutch cools down), which is a sign that the pressure plate spring metal soften with heat. The organic disc looked quite worn too.
From my research I concluded that 4-puck cluches are almost undriveable in traffic, yet most of the Sachs 4-puck reviews stated that the clutch drives quite well. I am sure the clutch material is very important in driveability, and I imagined that if someone would make a good puck clutch material, that would have to be Sachs.
You cannot imagine how nervous I was installing a 4-puck clutch. I like to drive my car around town and on holidays, I sometimes daily drive it so I was secretly hoping that the clutch would not be undriveable in stop and go traffic.
To my huge surprise, this clutch DRIVES ALMOST LIKE STOCK. I think I need to make a video for you to believe this
It doesn't even shudder when you engage the first gear, except in the first 2-3 kilometers after I left the service shop, where it had a very faint shudder, almost imperceptible when starting in 1st gear. I can go in reverse with no shudder whatsoever, I can park the car without any problem. Pedal effort is lower than ACT (but higher than stock), I really have to ask (the 3rd time) the vendor if they did reinforce my clutch plate. I guess I didn't notice that the ACT pedal was quite stiff (I do bodybuilding). The engagement point is higher, stock-like (I think that I can reinstall my clutch stop now). Now I really think that the majority of driveability problems with puck clutches come from the use of lightweight, single-mass flywheels. Or maybe there are many people who talk about puck clutches and few actually using them ?
Not sure.
I cannot tell you how happy I am that the driveability of the car was not altered by the clutch. How well it holds it remains to be seen, but I think it can't last shorter than the ACT. 20000 miles would be great. Before spending a huge amount of money on a HPF clutch or a ClutchMasters twin-disc, you may want to consider this one.
Posted are some pictures of the worn parts and the new clutch.