Is the Super Lock LSD for E30 M3 cars a direct replacement?

OS Giken USA lists the Super Lock LSD for E30 M3 cars, part number BM091-HA, for the manual E30 M3. It replaces the differential carrier and keeps the factory ring and pinion. Turn 14 also names some E34 automatic cars, which should be confirmed before ordering.

Why replace the original differential on an E30 M3?

The original unit on most cars is now decades old, and worn plates lock inconsistently or not at all. A new clutch-type Super Lock restores strong, repeatable locking and can be rebuilt and retuned by OS Giken in future rather than sourced as a used part.

Is it allowed in historic racing?

That depends on the series. Some historic classes require period-correct parts, while others permit modern limited-slip differentials. Check the regulations before ordering. Where allowed, the Super Lock suits the S14 car, and OS Giken can set it up for the circuit.

Will it change how the car drives on the road?

Very little in normal driving. OS Giken sets the Super Lock with a modest preload, and its Japanese catalogue rates the design among the quietest LSDs in town. The difference shows when the car is driven hard through slow corners.

Can it be retuned for a race car?

Yes. OS Giken retunes Super Lock units in-house. Thicker cone springs raise initial torque, different pressure ring springs change lock timing, and the ramp angles can be altered, so the same unit can be set for a road car or a dedicated racer.

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Description

OS Giken Super Lock LSD for E30 BMW M3 Manual

OS Giken’s Super Lock LSD for E30 BMW M3 Manual gives the homologation-special M3 a rebuildable, retunable clutch-type differential, a sensible step for a car whose original unit is now more than thirty years old. The E30 M3 was built to win touring car races, and owners who still drive theirs on track want a differential that locks consistently session after session. OS Giken’s patented pressure ring locks progressively under power, so the high-revving S14 four puts its drive down through both rear tires out of slow corners. It suits a race-prepared E30 M3 or a road car that sees regular track days.

Design and Performance

The friction plates sit on splines through the side gears, so OS Giken fits up to twice as many as competing designs. That plate area allows a modest preload for road use with full, progressive lock on throttle. Gears are raw-forged and the case is machined from a single billet, and OS Giken can rebuild and retune the unit in-house.

Features

Clutch-type rear differential for the S14-engined E30 M3
Patented pressure ring for consistent, progressive lock
Up to twice the friction plates of competing designs
Rebuildable and retunable by OS Giken
Billet case and raw-forged gears
Suited to historic racing and track days

Applications

BMW M3: E30 | 1988-1991 | 2.3L S14, manual

Notes

The Super Lock LSD for E30 M3 cars is listed by OS Giken USA for the E30 M3; Turn 14 also names E34 525i, 530i and M5 automatic cars, which should be confirmed before ordering
Installation labor is not included

Frequently Asked Questions

Is the Super Lock LSD for E30 M3 cars a direct replacement? OS Giken USA lists the Super Lock LSD for E30 M3 cars, part number BM091-HA, for the manual E30 M3. It replaces the differential carrier and keeps the factory ring and pinion. Turn 14 also names some E34 automatic cars, which should be confirmed before ordering.
Why replace the original differential on an E30 M3? The original unit on most cars is now decades old, and worn plates lock inconsistently or not at all. A new clutch-type Super Lock restores strong, repeatable locking and can be rebuilt and retuned by OS Giken in future rather than sourced as a used part.
Is it allowed in historic racing? That depends on the series. Some historic classes require period-correct parts, while others permit modern limited-slip differentials. Check the regulations before ordering. Where allowed, the Super Lock suits the S14 car, and OS Giken can set it up for the circuit.
Will it change how the car drives on the road? Very little in normal driving. OS Giken sets the Super Lock with a modest preload, and its Japanese catalogue rates the design among the quietest LSDs in town. The difference shows when the car is driven hard through slow corners.
Can it be retuned for a race car? Yes. OS Giken retunes Super Lock units in-house. Thicker cone springs raise initial torque, different pressure ring springs change lock timing, and the ramp angles can be altered, so the same unit can be set for a road car or a dedicated racer.

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 E30 BMW M3 Manual [BM091-HA]

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OS Giken Super Lock LSD for E30 BMW M3 Manual

Design and Performance

Features

Applications

Notes

Frequently Asked Questions

About OS Giken

Reviews