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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
4.0 ★★★★★
Based on 19 reviews
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Product Reviews
★★★★★ 5
Surprisingly great for my wide feet and high instep!
Size: 10.5, Color: Velvet Tan/Gum 2
So thrilled I took a chance on these. Finding boots is impossible for me. I have wide feet, a super high instep, a bunion on one foot, and I wear a hard to find size (10.5). I ordered the 10.5 and 11 in these expecting I might need to size up for width (if I could even get them on). It was a struggle getting the 10.5s on the first time, and once I did they were somewhat uncomfortable on the top of my left foot. But I read that they would relax so decided to give it a go because I need waterproof boots for an upcoming trip and the 11s felt too long. After two days of light wear, they are already breaking in and I have no more discomfort. Getting them on is already easier and they are plenty wide enough and very comfortable to walk in. These are true to size. Super happy and worth a day of mild discomfort to break them in!
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Reviewed in the United States on March 7, 2026
★★★★★ 5
Comfortable, sturdy, waterproof
Size: 9.5, Color: Black/Black
Loce, love, love these boots. Have walked ten miles with no foot pain around NYC. They go with everything and and are so comfortable. As they are waterproof/resistant, they get a little warm in high temps, but perfect three-season boots.
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Reviewed in the United States on May 17, 2026
★★★★★ 5
Super cute, comfortable, practical, love that they are slip on
Size: 10.5, Color: Tobacco/Black
I have worn these 2-3 times already. The first day was a school/work day so I was on my feet 9 hours and the only issue I had was with the side of the boot rubbing against my ankle. I just make sure I wear socks high enough to cover my ankles or jeans that go into the boots now for long wear days.
Absolutely love them! They keep my feet dry in this snow( we live in Michigan). I had been looking for a pair like this for awhile now and was getting super frustrated that I couldn't find my size in any that I liked. I saw that they had these available in a 10.5 and I wear 11. I looked at the Sorel website reviews (since the amazon ones weren't super helpful on sizing) and they said that the boots ran big so I took a chance on the 10.5 fitting me. They fit perfect. I have long narrow feet but I could see where they would be tight or uncomfortable on someone with wider feet. I've been trying to find a pair for my mom now since she has boot envy.
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Reviewed in the United States on January 27, 2026
★★★★★ 5
Worth it.
Size: 8.5, Color: Crushed Clay/Gum 2
Love all my Sorels. These were really cute, good color, comfortable, warm, fit well, good quality and sturdy. I would order again.
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Reviewed in the United States on March 26, 2026
★★★★★ 5
Fantastic Boots!
Size: 8.5, Color: Redwood/Gum 10
Completely satisfied with these boots. True to size, well made, comfortable from the get-go; not break in needed. Waterproof- really. The Red Suede has withstood a nasty winter season & still looks great. Good traction. I like the ankle height which looks good with long, mid length pants & leggings. I love the easy slip on/off aspect..made getting ready for dog walking easy. I 100%recommend!
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Reviewed in the United States on April 11, 2026