ACT HD pressureplate, Prolite Flywheel and Performance Street Disc review

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Review ACT prototype HD pressureplate, Prolite Flywheel, and Performance Street Disc

Before I start with my write-up, I want to thank the ACT team, and Chad for giving me the opportunity to be part of their product development. ACT has treated me in a world class professional manner which also translate to the excellent product and services they provide.


Background June 2012,


The story begins when I have become one of the lucky one who took delivery of the 2013 BRZ on Memorial Day 2012. Soon after, I began contacting local performance parts manufacture listed in Lonewolf’s thread, and ACT was one of them. Prior to contacting ACT, I know very little about aftermarket clutch options and even less with regards to the capability and limitation of each selection. Soon after I contacted ACT, I have received an e-mail from Chad, ACT’s design engineer to discuss the development effort in detail. First we discuss the logistic, and then He educates me on the different products, their strength and weakness. By the end of our conversation, we have selected a date for drop-off. Throughout the time where my car was at ACT, chad has been giving me frequent updates, as well as his finding. He has made this development processes transparent which allow me to have full confidence with regard to the wellbeing of my car. Two weeks later, the project is done and I came home with the ACT clutch kit prototype. During pickup, Chad has also given me a tour of the ACT factory (which is right behind the office). During the tour, he has shown me that everything ACT build is either in house or from OEM blanks.

ACT have installed 3 products on my car, I will explain what they do and how they perform below.

HD Pressure plate: http://www.advancedclutch.com/sb017

This pressure plate weights 10.6 lb and it have 70% increases in clamping load. At the moment, this is the only offering from ACT for our car. The reason why ACT didn’t offer any other pressure plate is that since our car is consider relatively light, the 70% increase in clamping load would be sufficient to hold any force induction application w/o adding additional stress to the drive shaft bearing.
During the initial discussion I had with ACT, I had let them know that the ambiguity in the clutch grab was a big concern, where many drivers’ feels disconnected with the clutch engagement. In addition, the OEM clutch can feel plushy under some harsh driving condition.
With the HD pressure plate install, I was able to notice a slight increase in the firmness of the clutch pedal w/o being stiff (think of an old car without clutch boost). The grab/slip points of the clutch actuation have also become more distinct and linear. Because of the HD pressure plate installation, I was able to accurately feel the friction zone in a repeatable manner. In addition, the initial engagement of the clutch after the friction zone feels solid. I now can apply throttle immediately without any slippage.

Performance Street Disc: http://www.advancedclutch.com/3000504
This is the entry level default clutch disc (3.3lb) that blends streetability and performance. ACT also offers their 4 pad and 6 pad versions which are both lighter while sacrificing steetability.
With this street disc, I’ve notice the friction zone is decrease from OEM setting but the engagement is more linear and positive. In addition, during performance driving, the OEM clutch tends to get even plushier due to heat while the Performance Street Disc retains the same firm engagement feedback.
The down side to a lighter clutch disc is that it lacks the vibration dampening of the OEM setup. As a result, in idle when engine is warmed up, I will hear the gears teeth raddling while in natural. More over at certain RPM (around 2500 to 3000) I have also experience high frequency vibration coming from that RPM zone.

XACT Prolite Flywheel http://www.advancedclutch.com/600700
ACT is currently offer two version of the flywheel. Mine is the 10.5 lb which is more suitable for racing application while the other is 11.5 lb which maintain drivability.
With the prolite flywheel, the engine is noticeably more responsive or “rev happy”. The car really comes alive during harsh acceleration. In addition, the 3-4 K torque dead zone almost disappear. However, due to the light flywheel, the engine will not be able to store as much energy as the OEM setup. As a result, the RPM drops down just as fast as it goes up, which means if I am not careful, I would stall frequently during stop and go traffic. This gets better with more practice.

Summary:

Pros:
1. The entire ACT clutch assembly is 24.4 lbs vs 38lb. that’s a wooping 13.4 lbs difference.
2. A noticeable increase in Engine response.
3. A noticeable increase in firmness and linear response of the clutching experience.
4. When driving under harsh acceleration and deceleration, the clutch feedback retains its firmness.
5. The total shifting time is also quicker because of the more positive feedback, quicker grab, and more solid torque delivery.
6. Possible HP / Torque increase due to less drivetrain mass.
7. Everything is made in USA . Unlike other internet speculation.

Cons:

1. Due to lower mass, the vibration damping of the clutch system is reducing. Though you won’t feel any vibration coming though the transmission, you can hear it. Personally, I can live with it knowing the tradeoff.
2. Decrease steetability. I now frequently stall during takeoff due to the fact that the engine RPM now drops at an accelerated rate in addition to a shorter friction zone.
3. Possible aggravated idling issue when combine with other bolt on modification.


Note:

Concerns about CEL:

During the initial installation, I did not encounter a CEL. However, I did have experience some idle fluctuation. Upon researching, someone has suggested me to disconnect the battery so the ECU will reset itself. This method worked and the idle fluctuation was stabilized.
The correction procedure is as follow:
1. Disconnect the battery.
2. Leave the battery off for 3 min. this allows the ECU to discharge and erase information store in the RAM.
3. Reconnect the battery.
4. Turn on the car and let the car idle for 2-3 min.
5. Drive 3-5 miles in mild street driving condition.


Concerns about lite flywheel & light pulley:

During the initial installation, I have encountered both CEL and idle fluctuation. However, both CEL and idle fluctuation was clear after I perform the correction procedure listed above. The CEL and idle fluctuation did not comeback.