Why replace the Variable M Differential Lock?

The factory unit on the E46 and E9X M3 is speed sensing: it only begins to lock once one rear wheel turns faster than the other. On track that means the inside tire spins before the lock arrives. A clutch-type Super Lock LSD for E46 and E9X cars locks with torque from the start.

Does the Super Lock LSD for E46 fit the E9X M3 V8?

Yes. OS Giken USA lists part number BM237-HA for the E46 and E92 M3 and tags the E39 M5. The E9X M3 range includes the E90 sedan, E92 coupe and E93 convertible. Turn 14 also names other BMWs for this part, so confirm fitment for anything outside the listed cars.

Is it suitable for drifting an M3?

Yes. A clutch-type rear differential locks both wheels under power, making slides easier to start and hold than with the speed-sensing factory unit. OS Giken can retune initial torque and lock timing for a more aggressive drift setting. It holds through long sessions.

Will it be harsh on the street?

OS Giken sets the Super Lock with a modest preload that still reaches full lock progressively, and its Japanese catalogue rates the design among the quietest LSDs in town. Some plate engagement may be felt in very tight parking turns, which is normal.

Does the ratio change?

No. The Super Lock replaces the differential carrier and keeps the factory ring and pinion, so the final drive ratio is unchanged. Owners who want a different ratio would change the ring and pinion at the same time, while the differential case is out of the car.

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Description

OS Giken Super Lock LSD for E46 / E9X BMW M3 and E39 M5

OS Giken’s Super Lock LSD for E46 / E9X BMW M3 and E39 M5 replaces the M car’s factory rear differential with a clutch-type unit that locks with torque rather than with wheel speed difference. The E46 and E9X M3 left the factory with BMW’s Variable M Differential Lock, a speed-sensing design that works well on the road but only reacts once the inside rear tire is already turning faster, and on track it lets the S54 or S65 spin a wheel out of slow corners. OS Giken’s patented pressure ring locks progressively as the throttle opens. It suits an M car driven hard on circuits or at drift events.

Design and Performance

The plates run on splines through the side gears, which lets OS Giken fit up to twice the friction plates of competing designs, giving the clamping area for a high-revving straight-six or V8. A modest preload keeps the car civil on the road, with smooth, progressive lock under power. Gears are raw-forged and chemically heat treated.

Features

Clutch-type rear differential for the S54, S65 and S62 M cars
Locks with torque instead of waiting for a speed difference
Patented OS Giken pressure ring for progressive lock
Up to twice the friction plates of competing designs
Billet case and raw-forged gears
Retunable by OS Giken for track or drift

Applications

BMW M3: E46 | 2001-2006 | 3.2L S54
BMW M3: E90 / E92 / E93 | 2008-2013 | 4.0L S65 V8
BMW M5: E39 | 2000-2003 | 5.0L S62 V8

Notes

The Super Lock LSD for E46 and E9X M3 and E39 M5 cars is listed by OS Giken USA for these three models; Turn 14 also names the E60 M5 and M6 and other BMWs, which should be confirmed before ordering
Installation labor is not included

Frequently Asked Questions

Why replace the Variable M Differential Lock? The factory unit on the E46 and E9X M3 is speed sensing: it only begins to lock once one rear wheel turns faster than the other. On track that means the inside tire spins before the lock arrives. A clutch-type Super Lock LSD for E46 and E9X cars locks with torque from the start.
Does the Super Lock LSD for E46 fit the E9X M3 V8? Yes. OS Giken USA lists part number BM237-HA for the E46 and E92 M3 and tags the E39 M5. The E9X M3 range includes the E90 sedan, E92 coupe and E93 convertible. Turn 14 also names other BMWs for this part, so confirm fitment for anything outside the listed cars.
Is it suitable for drifting an M3? Yes. A clutch-type rear differential locks both wheels under power, making slides easier to start and hold than with the speed-sensing factory unit. OS Giken can retune initial torque and lock timing for a more aggressive drift setting. It holds through long sessions.
Will it be harsh on the street? OS Giken sets the Super Lock with a modest preload that still reaches full lock progressively, and its Japanese catalogue rates the design among the quietest LSDs in town. Some plate engagement may be felt in very tight parking turns, which is normal.
Does the ratio change? No. The Super Lock replaces the differential carrier and keeps the factory ring and pinion, so the final drive ratio is unchanged. Owners who want a different ratio would change the ring and pinion at the same time, while the differential case is out of the car.

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 E46 / E9X BMW M3 and E39 M5 [BM237-HA]

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OS Giken Super Lock LSD for E46 / E9X BMW M3 and E39 M5

Design and Performance

Features

Applications

Notes

Frequently Asked Questions

About OS Giken

Reviews