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Description
bmw gear ratios BMW Differential Gear ratio Swap set - Essential for smooth gear ratio changeBMW Gear Ratio Swap Set Complete Installation Kit (168 188 210 mm) Thinking of changing the gear ratio of your BMW differential? The RacingDiffs Gear Ratio Swap Set includes all essential components to complete a precise, reliable swap and unlock better acceleration, drivability, and overall performance. Key Features Complete kit: Everything required for a seamless gear ratio change with factory level precision. Performance gains: Tailor acceleration,
BMW Gear Ratio Swap Set — Complete Installation Kit (168 / 188 / 210 mm)
Thinking of changing the gear ratio of your BMW differential? The RacingDiffs Gear Ratio Swap Set includes all essential components to complete a precise, reliable swap and unlock better acceleration, drivability, and overall performance.
Key Features
- Complete kit: Everything required for a seamless gear ratio change with factory-level precision.
- Performance gains: Tailor acceleration, top speed and gear spacing to your driving style and tracks.
- OEM-grade quality: Components meet or exceed OEM specs for durability and long service life.
What’s in the Box
- Adjustment Shim Set / C-Clip Set — ensures proper alignment and backlash adjustment.
- Pinion Oil Seal — maintains lubrication and prevents leaks.
- Large Pinion Bearing — to press onto the new pinion gear.
- Crush Sleeve Shim — for setting correct pinion preload.
- Pinion Depth Shim Set (3.3–3.7 mm) — precise pinion depth positioning.
Performance Benefits
- Stronger acceleration with shorter final drives; or reduced cruising RPM with taller ratios.
- Improved drivability by matching ratio to engine power band and tire diameter.
- Long-term reliability when preload/backlash are set correctly during assembly.
- Expert support — guides and resources to help you complete the swap confidently.
Fitment Confirmation
- Use the BMWFans.info database: Follow this guide video to identify your differential type and parts: How to check diff type.
- VIN check: Send us the last 7 digits of your VIN and we’ll confirm the correct set for your car: Contact RacingDiffs.
Works with common BMW differential sizes: 168 mm, 188 mm, and 210 mm. Verify exact application before ordering.
Technical Specs / Installation Tips
| Pinion depth | Set using the Pinion Depth Shim Set (3.3–3.7 mm). Verify with contact pattern. |
| Pinion preload | Establish with the Crush Sleeve Shim per BMW specs (feel for smooth rotation, no end play). |
| Backlash | Adjust via Adjustment Shim / C-Clip Set until within spec; measure at ring gear with a dial indicator. |
| Sealing | Install the new Pinion Oil Seal; lightly oil lips; inspect yoke surface for grooves. |
| Fasteners | Clean threads, apply medium-strength threadlocker to ring-gear bolts, torque in a star pattern to BMW spec. |
Re-check preload and backlash after the first heat cycle or track session.
OEM Cross-References (Backlash Adjustment Shims)
| Diff Size | OEM Part Numbers |
|---|---|
| 168 mm | 33139065731 / 33-13-9-065-731 / 33 13 9 065 731 / 33.13.9.065.731 33139065732 / 33-13-9-065-732 / 33 13 9 065 732 / 33.13.9.065.732 33139065733 / 33-13-9-065-733 / 33 13 9 065 733 / 33.13.9.065.733 |
| 188 mm | 33139065734 / 33-13-9-065-734 / 33 13 9 065 734 / 33.13.9.065.734 33139065735 / 33-13-9-065-735 / 33 13 9 065 735 / 33.13.9.065.735 |
| 210 mm | 33139065736 / 33-13-9-065-736 / 33 13 9 065 736 / 33.13.9.065.736 33139065737 / 33-13-9-065-737 / 33 13 9 065 737 / 33.13.9.065.737 |
If you’re unsure about compatibility, send us the last 7 digits of your VIN and we’ll confirm the correct set for your build.
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy