On July 20 event of the 2009 Mobil 1 Solo Sprint Series, I ran into some unforeseen problems. Only having ran 10 minutes into the warm-up session, my car suddenly became very difficult to shift and soon after, became impossible to shift while the vehicle was on. My first instinct was that my friction disk broke allowing the clutch spring to pop out and jam between the pressure plate.

Upon pulling the transmission, I noticed that my assumption was correct. I needed a new clutch and fast seeing as I had a 2-day event coming up in just 2 weeks. OS Giken was able to provide me with support and rush shipping to get my car put together in time for my next event. I was assured that despite the clutch being a twin plate and unsprung, it would be fairly easy to drive while capable of holding much more power than I currently make on my K24A2 motor. I thought this would be a good route to take considering that if I decide to add forced induction; at least I would not have to worry about upgrading my clutch in the future. Of course, I was hesitant about using the clutch since my car happens to be my daily driver as well as my track car.

After the OS Giken twin plate clutch was installed on my car I took it out for a drive to break in the clutch and ensure everything was working properly. During the test drive, I was shocked. The pedal feel was only a little bit firmer than stock although having a much higher clamping ability. Also, unlike every other twin disk unsprung clutch Ive driven, the clutch was easy to drive, easy to feather and had virtually no clutch chatter whatsoever. Here was a clutch that I could live with driving through rush hour traffic and capable of tolerating track abuse. The best part is now I dont have to risk popping out the clutch spring and ruining another track day. I would highly recommend anybody shopping for a performance clutch in any build stage for their car because the OS Giken clutch is both street-able and capable for the track.

When racing with the OS Giken twin plate clutch, it is very easy to rev-match and perform a smooth downshift. This is due to the characteristic of the clutch providing a positive feel and allowing the driver to feather the clutch resulting in smoother shifts to prevent unsettling the cars balance in a competition situation.

Quick facts: On a regular bathroom scale, the OS Giken TS2A clutch for DC5 weighs 22lbs for the whole assembly. The OEM Type S Clutch with an ACT ProLite flywheel weighs 18lbs. The OEM Clutch with OEM flywheel weighs about 26lbs. A lighter-weight flywheel for the twin plate clutch can be special ordered.

Where do I start? I set a new personal best at Stratotech Park by 1.2 seconds. My old personal best set back in July 5 was 1:08.9 and my new personal best on August 3 was 1:07.7. The same timing system was used and for those who are curious, we used transponders with each driver having their own assigned transponder number.

To be perfectly fair and honest, several things was been changed since my previous personal best which was set 2 months ago. I recently got bigger tires (255/40-17 Dunlop Direzza Sport Z1 Star Specs) instead of my (245/40-17 Bridgestone RE-01R). The weather during the event was also cooler by 10 degrees Celsius and I had a slight change in alignment to make my car more stable. I ran the Star Specs with nearly full tread depth (9/32) and when I ran on my RE-01Rs, they were at about 4/32 tread depth.

Now the fun begins, how much time was gained with the OS Giken Super Lock LSD? Assuming that having tires 1 size larger, a cooler track day and a small change in alignment resulted in a 1 second difference in time, there is still a 0.2 second improvement. I dont know what other people think the recent changes account for in time, but I for one personally think the gains of changing to the OS Giken Super Lock LSD to be closer to 0.5 seconds.

When I was running on this differential, just like the clutch, I was very impressed and surprised at the same time. The OS Giken clutch-type LSD has one of the most clutch plates in the LSD on the market. The clutch operates smoothly and quietly just like OS Gikens clutch and the limit is easy to feel. One of the best characteristics of the Super Lock LSD, other than the quiet operation and smooth engagement, is under normal driving conditions and upon entering corners during competition, the LSD feels like the original OEM open-differential and does not cause the car to push upon corner entry.

The OS Giken LSD replaced my Quaife LSD and the gains are almost as significant as my Quaife LSD over the OEM open differential. One thing I noticed for sure was improved grip levels when Im rolling onto the gas past neutral throttle. I was able to apply power sooner and harder and use the Super Lock LSD to help me hold my desired line while I unwind the wheel for corner exit. Another thing I noticed with the OS Giken LSD is it gives me the choice of running slightly different lines as the car would not push out as much under power. For certain corners, if I wanted the car to hold a tighter line, the LSD would allow me to do so. Although the OS Giken LSD costs more than my Quaife, the gains are well worth it and Im glad I made the jump to upgrade to an OS Giken Super Lock LSD.