OS Giken's STR series racing clutch provides both race-ready performance as well as everyd
Clutch
In the case of the NSX, ponying up for a high-quality aftermarket clutch is a good idea because the stock twin plate clutch kit for the 5-speed transmission-which includes flywheel, pressure plate and friction discs-costs more than $1,600. Even if you bought it in separate parts, the pressure plate only comes in the entire kit. Our clutch was fried and looked like it was the original unit when the car was built.
We also went to OS Giken for its twin plate metallic disk STR clutch kit. The hardware is a direct bolt-on for the 5-speed transmission and reduces the overall rotating mass by about 10 lbs. Furthermore, the Giken STR clutch kit includes a new clutch slave cylinder and throw out fork to change the stock pull-type configuration to a push-type clutch, which is easier to service and less prone to wear. The clutch is rated for a higher clamping force, which isn't really necessary in our case but does engage much faster and have a metallic rattle when the clutch pedal is engaged due to the friction plates moving about.
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OS Giken's twin plate STR clutch kits comes with the entire clutch assembly already mounte
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With the new slave cylinder installed, we tried both leverage points available on the thro
With much help from Mark at MD Automotive, we managed to reassemble the transmission to the engine, drop it back into the rear subframe and finally drop the car back onto it. Once again, much easier said than done. The next debacle was over what gear oil to run since both the differential and the gears share the same oil. Honda's MT transmission oil is essentially 10W30 motor oil and is extremely thin for gear oil, which means Honda transmissions are built to relatively tighter clearances. OS suggests its own specially formulated full synthetic OS-250R differential oil for the Super Lock LSD. This would give the exact amount of friction in the differential for the locking plates to operate optimally. Unfortunately, it only comes in a very heavy 80W250 weight, which might cause havoc on our pristine new synchros. We finally settled on breaking in the new transmission and seating all the gears and synchros with standard Honda manual transmission fluid for the first couple hundred miles. Hopefully, all the gears would be happy by then and we would switch over and see if the transmission liked the OS gear oil.
While the Super Lock LSD worked reasonably well with the Honda MTF, there was a bit of clunking and popping from the diff during tight maneuvers due to the low weight gear oil. Even so, the Super Lock LSD is much more quiet than any other clutch-type LSD we've ever used. We didn't bother with the typical tight figure-8 break in, but did manage to beat on the diff a little prior to changing fluids. We saw little to no debris when it was drained, which was a good sign that everything was put together right. Although we had reservations about putting the heavy weight OS gear oil into our very expensively rebuilt transmission, we did want to try it for the sake of the LSD. As it turned out, the heavy Synthetic OS gear oil was just as smooth to shift under summer conditions and got rid of much of the excess popping from the diff. To really test the new gears out, we headed off to California Speedway to repeat our quarter-mile and figure-8 tests to see what we gained.