OS Giken BMW Differential and Gearing Upgrades for BMW 5 Series E34 (1987-1995)

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Upgrading various parts of the differential can have tremendous benefits in your car's performance. It's easy to forget that the differential is a source for making your car faster and handle better so it's often overlooked. The engine is not the only place to make the car faster. Our differential options vary from gearing upgrades to limited slip conversions. You can purchase the ring & pinion gear sets on their own (professional installation required) or have us build a diff around your own specifcations. The options are almost endless! Every custom-built diff is fully rebuilt with seals and bearings. We also design and supply bushing options to reduce driveline wind-up, finned differential covers for better cooling, and more!

Ratio Changes - Changing the differential gearing is one of the best and most-effective upgrades you can make on any BMW (old or new). By using a shorter (numerically higher) final drive ratio you are increasing your RPM relative to road speed - this puts you in a more powerful RPM range than before! Since you're in a 'meatier' part of the power band you're now putting down more power/torque to the ground. If you can trade outright top speed for faster acceleration at daily speeds then this is the perfect upgrade for you.

Limited Slip Upgrades - Sadly, many BMWs today are not equipped with a limited slip (posi-traction) differential. BMW has tried to compensate by using traction control that cuts power at the engine or applies the brakes to retard wheel spin (or a combination of both). But nothing beats the function and feel of a a true LSD which may be why BMW continues to use them in M cars. Our LSD upgrades can be done a number of different ways - a factory-type limited slip unit with either 2 or 3 clutch packs, helical type, OS Giken unit, or something truly custom. We can also vary ramp angles and setup to change the limited-slip behavior under acceleration, deceleration, and cornering. Need a custom diff? Call or e-mail to have a quote.
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E46 M3, E9X M3, E34 M5, E39 M5, Z4 M OS Giken Super Lock Limited Slip...
affirm Starting At 0% APR - Subject To Eligibility. See Lending Terms
OS Giken - Corporate Logo
T#:1387
Part#: BM237-HA
Special Order: No Guaranteed ETA
$ 1,950.00 USD
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$ 1,950.00 USD
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The M Dynamic limited slip unit on the M3 is designed to be a pure street car differential. It's simply not up to the rigors of professional or amateur racing. The OS Giken Super Lock LSD is giant step up in from a stock M3 lsd unit. It's ready for the extreme conditions of racing, offers 100% progressive locking capability, and is able to do this while operating smoothly and quietly. It's use of advanced technologies that make it perfect for both street cars AND pro race cars... and everything in between. We're excited to be carrying the OS Giken LSD unit in our performance catalog, as we've been using them in our own Championship winning M3 race cars.

OS Giken incorporated revolutionary new ideas when developing the their own limited slip diff, utilizing their accumulated racing knowledge and experience and over 4 years of development. Their design uses an unprecedented number of friction plates (up to 28 total!) for better locking force, better engagement/disengagement, and less generated heat. The end result of their efforts is the OS Giken's OS Super Lock LSD which offers incredible durability and reliability on street and track driven BMWs. The use of highest quality materials, precise machining, forged gears and sound engineering makes this LSD durable and reliable enough for road racing performance (which we can personally vouch for!). This is such a great design, in that it can be used in any situation -- whether it's for a street car, or a 100% Professional race car. Zero break-in required. Super smooth and quiet engagement, and 100% progressive locking capability. Professional installation is recommended.

This Limited Slip Differential Unit fits the following BMWs:
2001-2006 E46 M3 coupe & convertible
2008-2013 E9X M3 coupe & convertible
1991-1995 E34 M5 sedan
1999-2003 E39 M5 sedan
2006-2008 E85 Z4M Z4 M Coupe, Z4 M Roadster
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Differential And LSD Tune
affirm Starting At 0% APR - Subject To Eligibility. See Lending Terms
OS Giken - Corporate Logo
T#:34382136
Part#: BM237HAKT
Ships on Jul 17, 2026
$ 2,100.00 USD
Free Shipping on orders $49 and up
Upgrade to a better performing LSD, includes tune.
LSD Tune For OS Giken Differential
affirm Starting At 0% APR - Subject To Eligibility. See Lending Terms
OS Giken - Corporate Logo
T#:34382134
Part#: LSD-TUNE
Special Order: No Guaranteed ETA
$ 150.00 USD
Free Shipping
$ 150.00 USD
Free Shipping