Wavetrac ATB Helical LSD (215K) - BMW 335i E9x E90 E92 E93 3 Series - 2.81:1 Final Drive, Bolted OEM Ring Gear/Crownwheel - Torque-Biasing Torsen-Style Gear-Driven Rear Differential Upgrade Diff Centre

Part number: 215K — premium helical limited-slip centre for BMW 3 Series E9x 335i differentials using a bolted OEM crownwheel and 2.81:1 final drive. This gear-driven upgrade transforms traction, stability and corner-exit pace on fast road, track day and drag applications while retaining civilised road manners.

Why this helical limited-slip is the upgrade your BMW 335i needs

When one rear wheel gets light over kerbs, cambers or slick surfaces, open and conventional gear-type units can let drive fade away. This unit’s patented wave-cam mechanism generates internal load so torque is still directed to the tyre with grip. The result is consistent power delivery through bends, sharper throttle response and improved confidence on wet roads and circuit kerbs alike.

• Keeps driving the loaded wheel when an axle goes light over bumps or kerbs
• Smoother, more predictable power application near the limit for faster exits
• No clutch packs to wear, no chatter, minimal maintenance
• Excellent road manners and compatibility with factory stability and ABS systems
• Ideal for fast road, track day, sprint, hillclimb and drag use

Engineering highlights

• Patented wave-cam device maintains bias when one side sees near-zero load
• Carbon-composite bias plates deliver consistent performance over time
• ARP high-strength hardware throughout for durability
• 9310 alloy gearset inside a robust steel housing for long service life
• Designed and manufactured in the USA

Fitment details

• Vehicle: BMW 335i on the E9x platform (E90 E92 E93)
• Final drive ratio: 2.81:1
• Ring gear style: OEM bolted crownwheel
• Part number: 215K

For units with a bolted ring gear only. If you are unsure whether your rear axle uses a bolted or welded crownwheel, contact us before ordering.

Real-world results

We run these units on customer builds and our own development cars. The feedback is the same every time: stronger traction out of hairpins, calmer behaviour over kerbs, and confident throttle application in poor weather. It is a genuine step up for a fast road 335i that sees regular circuit use.

Who is it for

Drivers seeking a rear differential upgrade for BMW 335i E90 E92 E93 who want maximum traction without the drawbacks of plate-type diffs. Perfect as a helical LSD upgrade, torque-biasing differential solution or gear-driven rear diff for road and track.

Installation and support

Professional fitting recommended. We can supply and install at MJ Modifications in Warwickshire. For a fitting quote or advice on compatibility, email info@mjmodifications.co.uk.

Why buy from us

• Specialists in BMW drivetrain upgrades and performance parts
• Tried-and-tested on UK roads and circuits
• Friendly setup advice and aftercare

Search-friendly terms customers use

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