Why is the Super Lock LSD for Fiat 124 different from the MX-5 manual unit?

The Fiat 124 Spider and the automatic MX-5 use a different final drive from the six-speed manual MX-5, so OS Giken lists a separate Super Lock LSD for Fiat 124 and automatic ND cars, part number FT191-HA. The six-speed manual MX-5 takes part number MZ191-HA.

Does it suit the turbocharged Fiat?

Yes. The 1.4-liter MultiAir turbo delivers its torque quickly once boost builds, which is when an inside rear tire tends to spin. A clutch-type differential keeps both tires driving through that surge, so the car accelerates out of corners instead of losing drive.

Will it change how the car drives on the road?

Very little in normal driving. OS Giken sets the Super Lock with a low preload, and its Japanese catalogue describes the design as one of the quietest LSDs in town. The difference shows at the limit of grip, on corner exit.

Is it suitable for autocross?

Yes. Autocross courses are tight and low speed, which is exactly where a light roadster unloads its inside rear. A clutch-type differential keeps both wheels driving, and OS Giken can retune initial torque and lock timing for the course and tires.

Can it be rebuilt later?

Yes. The friction plates wear slowly with use, and OS Giken rebuilds and retunes Super Lock units in-house, changing initial torque, lock timing and ramp angle. That lets the differential follow the car if power, tires or use change over the years.

Description

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Description

OS Giken Super Lock LSD for Fiat 124 Spider and ND Mazda MX-5 Miata Automatic

OS Giken’s Super Lock LSD for Fiat 124 Spider and ND Mazda MX-5 Miata Automatic covers the two ND-platform cars whose final drive differs from the six-speed Miata: the Fiat with its 1.4-liter MultiAir turbo, and the automatic MX-5. Both share the roadster’s light rear end, so an open or torque-sensing differential lets the inside rear spin as soon as the car is loaded in a corner. OS Giken’s patented pressure ring locks progressively instead, which matters most in the turbocharged Fiat, where boost arrives in a rush. It is the right differential for a 124 or automatic MX-5 that sees autocross or track days.

Design and Performance

The Super Lock carries its plates on splines through the side gears, giving up to twice the plate count of competing designs. That plate area lets the unit run a light preload on the road and still reach full lock on throttle. Gears are raw-forged and every component is chemically heat treated in a billet-machined case.

Features

Clutch-type rear differential for the Fiat 124 and automatic ND
Progressive lock from the patented OS Giken pressure ring
Up to twice the friction plates of competing designs
Low preload for daily road use
Billet case and raw-forged gears
Retunable by OS Giken as the car develops

Applications

Fiat 124 Spider: 2017-2020 | 1.4L MultiAir turbo
Mazda MX-5 Miata: ND | 2016-present | 2.0L SKYACTIV-G PE, automatic

Notes

The Super Lock LSD for Fiat 124 and automatic ND cars is a different part from the six-speed MX-5 unit, MZ191-HA
Installation labor is not included

Frequently Asked Questions

Why is the Super Lock LSD for Fiat 124 different from the MX-5 manual unit? The Fiat 124 Spider and the automatic MX-5 use a different final drive from the six-speed manual MX-5, so OS Giken lists a separate Super Lock LSD for Fiat 124 and automatic ND cars, part number FT191-HA. The six-speed manual MX-5 takes part number MZ191-HA.
Does it suit the turbocharged Fiat? Yes. The 1.4-liter MultiAir turbo delivers its torque quickly once boost builds, which is when an inside rear tire tends to spin. A clutch-type differential keeps both tires driving through that surge, so the car accelerates out of corners instead of losing drive.
Will it change how the car drives on the road? Very little in normal driving. OS Giken sets the Super Lock with a low preload, and its Japanese catalogue describes the design as one of the quietest LSDs in town. The difference shows at the limit of grip, on corner exit.
Is it suitable for autocross? Yes. Autocross courses are tight and low speed, which is exactly where a light roadster unloads its inside rear. A clutch-type differential keeps both wheels driving, and OS Giken can retune initial torque and lock timing for the course and tires.
Can it be rebuilt later? Yes. The friction plates wear slowly with use, and OS Giken rebuilds and retunes Super Lock units in-house, changing initial torque, lock timing and ramp angle. That lets the differential follow the car if power, tires or use change over the years.

About OS Giken

OS Giken was founded in Okayama, Japan in 1973 by Masaharu Okazaki. It built the TC16 and TC24-B1 DOHC cylinder heads for Nissan L-series engines, began making multi-plate racing clutches in 1982 and started supplying OEM limited-slip differentials in 1983. Development of the Super Lock LSD began in 1997, and of the OS-88 sequential gearbox for the Skyline GT-R in 1998.

Additional Information

The Bulletproof Automotive website contains many thousands of products purchased in multiple different currencies. All of the prices are entered manually and accurately at the time of entry. Due to the consistently fluctuating international exchange rates, at times prices may not be able to be honored at their original intended rate. We apologize for any inconvenience this may cause, unfortunately our website is unable to compensate dynamically for what can at times be volatile changes in the cost of items due to currency values fluctuating, changes in prices from suppliers, changes in shipping and import duties, and other factors. Rest assured that any order you place on line will be at zero risk to you in this area. If in the event your order cannot be fulfilled at the original intended website price we will offer you a 100% refund, no questions asked. We will continue to do our best to maintain updated prices and we will always continue to offer our price match guarantees as well to ensure our prices are always the best for you. In short, prices may change without notice. It is always advised to give us a call prior to placing your order online to confirm availability and to confirm current pricing.

Shipping Policy

Items that are in stock in the US, either at Bulletproof’s warehouse or at a supplier’s warehouse, are generally delivered within 7-10 days. Special order items from overseas take considerably longer. As a courtesy Bulletproof offers delivery estimates to our customers which take into consideration manufacturer availability and shipping schedule. These estimates represent our best guess based on previous orders from the manufacturer and do not in any way imply a guaranteed delivery window. Many manufacturers work in a “just in time” inventory system and often take 2-20+ weeks to produce an item once an order is submitted. All deliverable items are then sent to our Japanese warehouse. Bulletproof ships a minimum of one full ocean freight container every month from Japan, oftentimes more than one a month. Ocean freight takes an average of 4 weeks. Typically it breaks down to one week in Japan for paperwork and customs, two weeks by boat and one week in US customs/clearance. Due to the wide number of variables between manufacturer and shipping schedules, delivery estimates are simply just that – estimates. We attempt to estimate conservatively and we usually deliver faster than our estimates suggest. It is not Bulletproof’s policy to guarantee delivery time of any special order item, this is impossible for us to do. By ordering you acknowledge that there is no required delivery ETA and an order may not be canceled or altered due to manufacturing or shipping delays, all ETA’s are provided as a best guess only. Please review the full Terms & Conditions here.

BP Pricing Difference

We do pricing a little differently on our JDM brands and we believe in making things simple and clear. No hidden fees or surcharges. Every price you see includes the shipping cost to our office in Los Angeles, California and all the associated taxes/duties/fees for bringing the products into the US. The only shipping you ever pay is from our facility in the US to your location. Be wary of resellers that don’t include the cost of international shipping in their pricing on JDM parts. While we believe we’ll always have the lowest all-in price on JDM products, we offer a price match guarantee for all authentic parts purchased from authorized dealers as well. For many international customers, it’s much more affordable to ship from the USA than from Japan directly, as the air freight and ocean freight costs are typically much less. However, for customers looking to ship directly from Japan outside of North America, or domestically in Japan, we can provide pricing specifically for that scenario. Please do not hesitate to contact us with any pricing questions or concerns. Please email us at sales@bulletproofautomotive.com with any inquiries.

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OS Giken Super Lock LSD for Fiat 124 Spider and ND Mazda MX-5 Miata Automatic [FT191-HA]

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OS Giken Super Lock LSD for Fiat 124 Spider and ND Mazda MX-5 Miata Automatic

Design and Performance

Features

Applications

Notes

Frequently Asked Questions

About OS Giken

Reviews