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Description
diff gear ratio BMW M Gear Ratio Swap Set | M3, M5, M6, Z4M Differential UpgradeBMW M Gear Ratio Swap Set Complete Installation Kit Enhance the performance and driving experience of your BMW M3, M5, M6, and Z4 M with the RacingDiffs Gear Ratio Swap Set. The kit includes all essential components to change your differentials gear ratio with factory level precision and reliability. Key Features Complete kit: All parts required for a precise, repeatable gear ratio swapno guesswork. Performance gains: Tailor acceleration and
BMW M Gear Ratio Swap Set — Complete Installation Kit
Enhance the performance and driving experience of your BMW M3, M5, M6, and Z4 M with the RacingDiffs Gear Ratio Swap Set. The kit includes all essential components to change your differential’s gear ratio with factory-level precision and reliability.
Key Features
- Complete kit: All parts required for a precise, repeatable gear-ratio swap—no guesswork.
- Performance gains: Tailor acceleration and drivability to your use case (street, track, time attack).
- OEM-level precision: Components manufactured to meet or exceed OEM specifications.
- Guided install: Step-by-step tutorial + video walkthrough linked below.
What’s in the Box
- Adjustment Shim Set — aligns and positions internal components correctly.
- Pinion Oil Seal — prevents leaks and maintains optimal lubrication.
- Large Pinion Bearing — required to install onto the new pinion from your new gear set.
- Crush Sleeve Shim — sets the correct pinion bearing preload.
- Pinion Position Shim Set (2.5–3.5 mm) — precise pinion depth adjustment.
Performance Benefits
- Stronger acceleration with the right final drive for your build and tracks.
- Optimized top-end and gear spacing for your engine’s power band.
- Long-term reliability when backlash and preload are set correctly.
- Expert support from RacingDiffs if you need guidance selecting shims or ratios.
Technical Specs / Installation Tips
| Use case | Gear ratio change on BMW M differentials (see fitment variants below). |
| Pinion setup | Set pinion depth using the Pinion Position Shim Set (2.5–3.5 mm) and establish correct preload with the Crush Sleeve Shim. |
| Backlash | Adjust with the Adjustment Shim Set until backlash is within spec; verify gear contact pattern with marking compound. |
| Sealing | Install the new Pinion Oil Seal; lightly oil lips; ensure no nicks on yoke surface. |
| Torque notes | Clean threads; apply medium-strength threadlocker on ring-gear bolts; torque in a star pattern per BMW spec. |
| OEM references | Backlash adjustment shims: 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) |
Tip: Always re-check preload/backlash after first heat cycle or track day.
Fitment (Variants)
Variant 1 (V1):
- E36 M3 (3.2 S52)
- E46 M3
- E28 M5, M535
- E34 M5
- E39 M5
- E24 M6
- E60 M5
- E63 / E64 M6
- Z4 M
Variant 2 (V2):
- E90 / E92 / E93 M3
If you’re unsure about compatibility, send us the last 7 digits of your VIN and we’ll confirm the right set for your car.
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
4.9 ★★★★★
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Product Reviews
★★★★★ 5
Treats and plenty of ball throwing with these doggie toy
Size: Medium (2.5"), Style: Fetch Pack 1
I have actually purchased these twice already. I love the one that glows in the dark but it still got lost in my yard lol. My dog is a big breed half pitt/Labrador so she did chew through one of them already. I play ball with her every single day but I DO have to take them away from her because she will destroy them. They are great to add in treats as well, that was one of the my favorite things about them as well. They do last just if you have an over zealous chewer do not let them keep them for long periods of time. They are a good value for the price. Buy them your dog will love it!
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Reviewed in the United States on August 2, 2025
★★★★★ 5
My Female GSD loves
Size: Medium (2.5"), Style: Fetch Pack 1, Size: Medium (2.5"), Style: Fetch Pack 1
Shasta is my smallest. Six in December (2025) along with her brother. She’s 100 lbs and outside, completely ball driven see last picture. Don’t let the size (2.5”) of these Chuck-It balls deter you. If your larger Breed dog has any orthopedic issues, has already torn their ACL etc, one has arthritis but wants to play. This size is perfect!
Shazzy was born with several ortho issues. I don’t throw balls distance but right to her. This size and lighter weight assure even when Shazzy is spazzy w excitement, she’ll catch the ball mid air.
The green balls are softer, and glow in the dark. In summer we can play well past dusk and I can see them!
Her personality shows in the pictures. Playing ball is part of her. These balls are just perfect for her situation. Somehow they disappear, she loves making baskets, puts them in my tractor bucket, or my gardening bucket..then get put in burn pile, trash etc. I keep replacing them because she’d look day and night if we actually ran out!! 🙏✝️👍🏼👍🏼
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Reviewed in the United States on September 3, 2025
★★★★★ 5
SHORT-game Ball Launcher … love it!
Yes, this is a smaller ball launcher … It is for her SHORT Game! Love it AND the squeaky baseball that came with it is A-HIT!! Our black golden doodle, Josie, carried that around for hours … batting it around, jumping on it, resting with it right-next-to-her. For your pup’s LONG game, purchase the longer launcher. GAME-on!
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Reviewed in the United States on May 23, 2026
★★★★★ 5
Works great with tennis balls
I have a pretty large yard, and this thrower is great for my little Jack Russel puppy. It even picks up ball without having to touch all the spit.
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Reviewed in the United States on April 14, 2026
★★★★★ 5
Its awesome
Perfect 👌
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Reviewed in the United States on April 7, 2026