My own TY's WB SPL Upgrade Version(E)

[Wheelz_In_Motion]

I just want to share with you guys what I found after a couple months of doing research through Nissan OEM parts and other interchangeable Nissan parts.

Later last year I visited my friend, who has several RB20, RB25 and RB26 engines in his shop and did some research that lead me to gather the following setup.

I learned that all RB20DET engines and early RB25DET engines share the same flywheel, consisting of a 240mm surface area. The flywheel of the early RB26DETT is a little bit different in thickness, but still is interchangeable between all of the above mentioned engines and also uses the exact same pressure plate as the 20 & 25 DETs, which happens to be the same as the one found in the 1982-1983 280ZX Turbo L28ET and 1984-1986 300ZX Turbo VG30ET. Then I compared the stock KA24DE flywheel to them, and they are completely interchangeable between all the aforementioned engines. Everything aligns perfectly, the starter to ring spacing is also perfect, and even the pilot hole aligns perfectly to the crankshaft.

Then I decided to do a search on lightweight billet chromoly flywheels and found that Gordon Duax sells these flywheels for the RB20DET engine, so I decided to purchase one, exactly like this one http://cgi.ebay.com/ebaymotors/ws/eB...m=190004506512. The construction of the flywheel is outstanding. It is made in Japan from a single piece of billet chromoly, and it is a lot lighter compared to the stock flywheel. There are other companies that sell those flywheels, but without any doubts, the best deal around is offered by Gordon.

During the time of deciding which 240mm pressure plate brand I should buy (ACT, Nismo, Cusco, Exedy, etc.) another friend bought, for his SR engine, a JWT flywheel and clutch system who uses a 250mm pressure plate from a 350Z/G35 and ask him to lend me his 250mm pressure plate, so I could compare it to the RB bolt pattern. To my surprise the bolt pattern is identical to the RB, and for an even greater surprise, the flywheel that I have has the exact same contact surface to accommodate the 250mm friction area with no problems. Knowing all this I decide to purchase an ACT pressure plate for the 350Z/G35 and use a 6 puck sprung carbotic disc for the 350Z/G35.

As a side note, I also have several friends running 350Zs with the Greddy TT setup, and they are already producing over 500 ft/lbs of torque using that same ACT pressure plate, with no problems. The carbotic material has a higher coefficient of friction compared to the organic and even to the "common" metallic material aka bronze. Due to the higher coefficient of friction the engagement is quick and sharp. Then I proceeded to install the setup using a set of RB26DETT flywheel to crank bolts, which are a little bit longer with a new 350Z/G35 release bearing.

A few weeks ago I talked to Gordon and told him about my findings and took the opportunity to ask him about his stock of RB flywheels. Right now he has a few left on hand, including a Tomei and another one from an unknown brand. My guess is that these flywheels are going to start selling fast as Gordon has included in another of his auctions the KA24 application.

Basically, the ingredients to build what I think is the ultimate single disc clutch system for the KA24DE engine are the following:

- Flywheel from a RB20DET engines or early RB25DET or early RB26DETT or better still use an aftermarket flywheel from the previously mentioned engines (like the one pictured below and like the ones that Gordon sells) that don't have the defined groove between the friction surface and pressure plate area. If your flywheel has that groove then the disc will not use all the contact area.

- Use a pressure plate, disc and throw out bearing from a Nissan 350Z/G35. Depending of what your goal is, you must decide which route to go. Whether you need a stock setup or a racing setup, is up to your goals and expectations. A stock OEM setup is good to around 350 ft/lbs of torque. Wanting more than that then you should start thinking better pressure plate and better disc material. Like always, the "trade off" is increased pedal pressure and crisper engagement.

- Preferably use the flywheel to crank bolts from a Skyline GTR, as they are about 3mm longer, which compensates for the flywheel thickness.

Below are some pics of the process and final results. Enjoy...


This is the actual weight of the stock clutch system at 33.88 lbs


This is the actual weight of the aftermarket clutch system at 28.88 lbs. Lightweight chromemoly flywheel from an RB20DET engine and 250mm ACT clutch from the 350Z/G35. I was able to reduce mass for a total of exactly 5 lbs.
















Our old trick for tightening the flywheel.

[Voltron]

Rad. How is the 6 puck feeling with the lighter flywheel? Drive in traffic much?

[Wheelz_In_Motion]

Voltron, the clutch bites hard and chirps 4th gear very easily. I haven't tried to chirp 5th gear yet, but I wouldn't be surprised if it did too. For my personal taste is a bit too aggressive, and when running with traffic is a little uncomfortable, because when engaging it vibrates enough for me... I knew the clutch was going to bite hard, as I have driven a few other 240’s with traditional 6 puck sprung metallic “bronze” clutches, but the carbotic seems to bite even harder than that. For that reason I will soon change the disc for the new ACT "Performance Street Disc" with P/N 3000409 and evaluate how it performs. We all know for sure that it will not hold as much torque as the carbotic, but still want to try how it behaves. Even though I only use my car a few times a month, I always want to try to keep the "stock like" feel whenever possible. For that reason I also installed a Nismo slave cylinder, and it did help alleviate the pedal pressure.

For now the street disc should be good enough, before I move my project to higher boost.

I'll keep you posted with the results as soon as I install the new street disc.