In order to finish first, you must first finish the race." This is a motto Okazaki-san of OS Giken has built his successful company around. Back in the 1970s preparing your car for racing in Japan was close to impossible because quality parts were so hard to find. People thought that extracting more power from their engines was synonymous with success, but failures to drivetrain components-not driver skill-were the determining factor in deciding who would win and who would lose the race. Okazaki-san saw an opportunity and took it, dedicating his life to developing and producing some of the most sought-after components in Japan. To find out more about OS Giken, we met up with Okazaki-san and his staff at the company's HQ outside Okayama City in the south of Japan.
Talking to the brains behind such a respected name in the automotive world is always intimidating, but this meeting with the Shacho (boss) couldn't have been better. As soon as we arrived, we got down to business, and it was obvious that even after so many years in the game Okazaki-san still has an outstanding passion for the products he creates. He talks with an assertiveness that commands respect from the people around him, but at the same time manages to create a family-type atmosphere within his workforce, something that is rarely seen within the extremely formal (most of the time) setting of a Japanese company.
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A closer look at the clutches inside OS Giken's limited-slip differentials.
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OS Giken manufacturers its clutches in-house with proven components and materials. You can
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These metal slugs will soon turn into custom-made gears for OS Giken's sequential transmis
The enthusiasm as he explains the general theories behind components like limited-slip differentials and sequential gearboxes is awe-inspiring, and I'm convinced that given enough time he would go on all day long. OS Giken values reliability as a top priority when creating its products, and some of the things we were first shown were the internal parts of a clutch and LSD that had been tested for more than 100,000 miles. Comparing them to equivalent products from other manufacturers also subjected to the same test, it was obvious that OS Giken parts were superior, showing a fraction of the wear and tear as their competition. Okazaki-san is especially proud of the Super Lock LSD (developed in three specific specs), the top-of-the-line item being impressively smooth and silent during operation thanks to specially grooved and drilled plates that provide optimal lubrication. He runs one in his Nissan Fuga (Infiniti M45) and even takes us out to feel for ourselves just how quiet it is!
Okazaki-san is always open to new challenges, which is why the company dedicates a lot of its time to one-off custom projects. These span from motorsport teams requiring tough components to deal with the rigors of racing, all the way to private customers trying to improve their import cars. One of the last custom LSDs the company created was for a Mercedes Benz C63 AMG.

Much like every shop in Japan, space is at a premium, so it's common to have a workshop an
Next up was a tour of the factory where some OS Giken components are built. On one side of the main factory floor, components arrive from the foundry ready to be machined like the forged ring billets, which will be turned into precise cogs for its gearbox kits. We were shown the full R33 Skyline GT-R close-ratio transmission upgrade, as well as the lightweight clutch fork for a JZA80 gearbox.
Most of the downstairs of the building houses the vast parts warehouse, where everything from replacement clutch plates and gear sets to camshafts and pistons are organized by car type on the tightly stacked shelves. We were taken to the special projects workshop where an R34 GT-R sequential transmission had just been put together ready to be dropped into the OS Giken branded aluminum housing.
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The many different types of flywheels that will soon be mated to twin- or triple-disc clut
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An OS Giken bellhousing complete with heavy-duty clutch fork. This isn't your average OEM-
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An OS Giken transmission housing is being machined here.
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