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Track-Proven Torque Control for the Mazda MX-5 ND1 and ND2 Platform
The OS Giken OSGMZ191-HA Super Lock LSD is engineered specifically for the 2016-2023 Mazda MX-5 Miata ND1 and ND2 with the 6-speed manual transmission. Purpose-built for the ND differential housing, it replaces the factory open differential with OS Giken's patented pressure ring, spline-through-side-gear design featuring up to twice the friction plate count of competing units. The result is a progressive, predictable limited-slip that eliminates inside wheel spin on corner exit without sacrificing the MX-5's trademark balance and feel.
Key Features
- OS Giken Super Lock 1.5-way LSD with patented pressure ring design
- Spline-through-side-gear construction for superior load distribution
- Up to 2x more friction plates than competing units for more consistent lockup
- CNC-machined billet differential case for maximum rigidity
- Ramp angles: 25 degrees acceleration / 35 degrees deceleration
- Lock Timing: 224 for smooth, progressive engagement
- Total friction plates: 20 for exceptional torque transfer
- Preload: 10S tuned for spirited street and track use
- Compatible with ND1 (2016-2018) and ND2 (2019-2023) platforms
- 6-speed manual transmission only, automatic not compatible
- Direct bolt-in replacement, no differential housing modification required
- Made in Japan by OS Giken to motorsport-grade tolerances
Fitment
| Year Range | Make | Model | Trim |
|---|---|---|---|
| 2016-2023 | Mazda | MX-5 Miata ND | Sport |
| 2016-2023 | Mazda | MX-5 Miata ND | Club |
| 2016-2023 | Mazda | MX-5 Miata ND | Grand Touring |
| 2016-2023 | Mazda | MX-5 Miata ND RF | Club |
| 2016-2023 | Mazda | MX-5 Miata ND RF | Grand Touring |
Specifications
| Detail | Value |
|---|---|
| Part Number | OSGMZ191-HA |
| Brand | OS Giken |
| LSD Type | Super Lock 1.5-way |
| Ramp Angles | 25 Accel / 35 Decel |
| Lock Timing | 224 |
| Total Friction Plates | 20 |
| Preload Setting | 10S |
| Platform Compatibility | Mazda MX-5 ND1 (2016-2018), ND2 (2019-2023) |
| Transmission Compatibility | 6-speed manual only |
| Material | Billet differential case, hardened friction plates |
| Country of Manufacture | Japan |
| UPC | N/A |
What's Included
- 1x OS Giken OSGMZ191-HA Super Lock LSD unit
- Friction plates and pressure rings pre-assembled
- Installation hardware
About OS Giken
Founded in 1969 in Okayama, Japan, OS Giken has spent over five decades developing precision drivetrain components trusted by professional racing teams at the highest levels of motorsport. Their Super Lock LSD series is engineered to the same exacting tolerances as their competition units, delivering race-derived performance in a streetable package. Every OSGMZ191-HA is manufactured entirely in-house and inspected before shipment.
Frequently Asked Questions
Does the OSGMZ191-HA fit the automatic transmission MX-5 ND?No. The OSGMZ191-HA is designed for the 6-speed manual transmission MX-5 ND only. The automatic transmission version of the ND uses a different differential configuration and is not compatible with this unit.
What is the difference between the ND1 and ND2 MX-5, and does this LSD fit both?The ND1 covers 2016-2018 model years and the ND2 covers 2019-2023 with engine and suspension revisions. The OSGMZ191-HA is compatible with both ND1 and ND2 platforms, as the differential housing and axle configuration remain the same across both generations.
What does a 1.5-way LSD do in a Miata compared to an open differential?An open differential allows the inside wheel to spin freely under acceleration in a corner, limiting traction and causing understeer. The OSGMZ191-HA's 1.5-way design applies lockup under acceleration and partial lockup under deceleration, sending power to the wheel with more grip and dramatically improving corner exit traction and driver confidence.
Will the OS Giken LSD cause any driveline noise or vibration on the street?Properly installed and serviced with the correct gear oil, the OSGMZ191-HA operates quietly on the street. Some minor engagement rattle at very low speeds is normal behavior for a mechanical LSD and is not a defect. Using LSD-suppressing additives is not recommended.
What gear oil should I use with the OSGMZ191-HA?OS Giken recommends 75W-90 GL-4 or GL-5 gear oil without friction modifier additives. Additives that reduce chatter will also reduce the friction plate engagement force, diminishing performance. Change the oil at 500 miles after installation and then follow a standard service interval of 15,000-20,000 miles or annually.
Can I rebuild or retune the OSGMZ191-HA after track use?Yes. OS Giken LSDs are fully rebuildable. Friction plates can be replaced when worn, and ramp angle components can be swapped to alter the engagement characteristics. OS Giken USA offers rebuild kits and technical support for customers who want to service or retune their unit.
Does the OSGMZ191-HA improve lap times at the track?Yes, consistently. Eliminating inside wheel spin on corner exit is one of the most significant performance gains available for the MX-5 platform. The OSGMZ191-HA delivers full-power exits from slower corners without the understeer and loss of rotation that an open differential produces, resulting in measurably faster lap times.
Is professional installation required for the OS Giken OSGMZ191-HA?Professional installation is strongly recommended. While the unit is a direct bolt-in replacement, proper ring and pinion backlash and bearing preload setup requires precision tools and differential experience. Incorrect setup can damage the differential and void any warranty.
Installation Overview
- Safely lift and support the vehicle, drain differential fluid completely
- Remove driveshaft, axle shafts, and differential rear cover
- Remove the OEM open differential unit from the housing
- Transfer the ring gear to the OSGMZ191-HA carrier using factory bolts torqued to specification
- Install the OSGMZ191-HA into the differential housing
- Set ring and pinion backlash and bearing preload per Mazda factory specification
- Reinstall differential cover, axle shafts, and driveshaft
- Fill with fresh 75W-90 GL-4/GL-5 gear oil to the correct level
- Perform a 500-mile break-in with moderate driving before track use
- Change gear oil at 500 miles, then follow standard service intervals
WARNING: This product can expose you to chemicals including lead and phthalates, which are known to the State of California to cause cancer and reproductive harm. For more information go to www.P65Warnings.ca.gov.
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