Wavetrac Differential For F20 & F21 M140i With 2.81 final Drive Axle

Most BMW axles from 07 onwards were manufactured with a friction welded ring gear and open differential. This can cause some headaches for installation concerning vehicle downtime while the factory differential/ring gear is separated by precisely machining the parts away.

Wavetrac Europe has now solved this for the M140i equipped with the 33107603760 2.81 215 axles. Have a 3.08 Final Drive? We also stock an axle for this too!

Please provide your VIN and transmission type at the checkout during ordering or prior to a member of staff by email or phone so we can verify which axle and ratio are correct for you so we supply the correct axle. 

Each exchange axle comes complete with the following:

1. Wavetrac ATB LSD
2. OE BMW ring gear bolts
3. New, Genuine BMW Axle Seals
4. Backlash Setup to OE Tolerances
5. Precisely Machined Ring Gear

You will need to spec oil, for this application we advise for Motul Competiton 75w140.

The exchange process is a simple 2 step process you can find below, we also offer a drive-in, drive-out service at our Southampton facility.

1. Pay for the product + the exchange deposit and we will send out to you a 30.309.172WKFM1/M140i
2. We will then refund the exchange deposit if a complete, usable (in good working order) axle is received within 10 working days. Axles which require maintenance/repair to be put into service or are not in working order will not be refunded.

 1' F20 LCI, M140i, 5 doors, B58, EUR, (1S91)

Applicable Models with 2.81 Final Drive 

33107603760 Axle: 

*Please provide VIN & Transmission Type before purchase or at checkout so we can verify the Final Drive of your vehicle. If the incorrect final drive axle is installed speed errors will be produced. 

• 1' F20 LCI, M140i, 5 doors, B58, EUR, (1S92) 
• 1' F21 LCI, M140i, 3 doors, B58, EUR, (1W91) 
• 1' F21 LCI, M140i, 3 doors, B58, EUR, (1W92) 
• 2' F22, M240i, Coupe, B58, EUR, (2G11) 
• 2' F22, M240i, Coupe, B58, EUR, (2G12) 
• 2' F23 LCI, M240i, Convertible, B58, EUR, (2N11) 
• 2' F23 LCI, M240i, Convertible, B58, EUR, (2N11) 
• 2' F23 LCI, M240i, Convertible, B58, EUR, (2N12) 
• 2' F23 LCI, M240i, Convertible, B58, EUR, (2N12) 
• 2' F23 LCI, M240i, Convertible, B58, USA, (2N13) 
• 2' F23 LCI, M240i, Convertible, B58, USA, (2N13) 
• 3' F30, 325d, Sedan, N47S1, EUR, (3D71) 
• 3' F30, 325d, Sedan, N47S1, EUR, (3D71) 
• 3' F30, 325d, Sedan, N47S1, EUR, (3D72) 
• 3' F30, 325d, Sedan, N47S1, EUR, (3D72)
• 3' F30 LCI, 325d, Sedan, B47, EUR, (8D31) 
• 3' F30 LCI, 325d, Sedan, B47, EUR, (8D31) 
• 3' F30 LCI, 325d, Sedan, B47, EUR, (8D32) 
• 3' F30 LCI, 325d, Sedan, B47, EUR, (8D32) 
• 3' F30 LCI, 325d, Sedan, N47S1, EUR, (8F11) 
• 3' F30 LCI, 325d, Sedan, N47S1, EUR, (8F12) 
• 3' F30 LCI, 340i, Sedan, B58, EUR, (8B31) 
• 3' F30 LCI, 340i, Sedan, B58, EUR, (8B31) 
• 3' F30 LCI, 340i, Sedan, B58, EUR, (8B32) 
• 3' F30 LCI, 340i, Sedan, B58, EUR, (8B32) 
• 3' F30 LCI, 340i, Sedan, B58, USA, (8B33) 
• 3' F30 LCI, 340i, Sedan, B58, USA, (8B33) 
• 3' F30 LCI, 340i, Sedan, B58, EUR, (8B35) 
• 3' F30 LCI, 340i, Sedan, B58, EUR, (8B35) 
• 3' F30 LCI, 340i, Sedan, B58, EUR, (8B36) 
• 3' F30 LCI, 340i, Sedan, B58, EUR, (8B36) 
• 3' F30 LCI, 340i, Sedan, B58, USA, (8B37) 
• 3' F30 LCI, 340i, Sedan, B58, USA, (8B37) 
• 3' F30 LCI, 340iX, Sedan, B58, EUR, (8B71) 
• 3' F30 LCI, 340iX, Sedan, B58, EUR, (8B71) 

1. Noise / Engagement Sounds Misinterpreted as Faults

Many owners across various cars with Wavetrac LSDs report audible noises on acceleration/deceleration that are often mistaken for mechanical faults, such as:

• Clicking or light “clunk” sounds when applying or releasing torque

• Sound during low‑load transitions that some interpret as gear or bearing issues

2. Installation Challenges & Fitment Issues

Because BMW rear axles from this era are single‑piece with a friction‑welded ring gear, fitting a Wavetrac requires:

• Separating and machining the factory ring gear and housing

• Backlash/preload setup to precise tolerances

3. Perceived “One‑Wheel Peel” Under No Load

Some owners testing their LSD on lifted wheels report that one wheel still spins freely — which people sometimes think means the diff isn’t working. However, helical LSDs like Wavetrac require torque/load on both wheels to bias torque effectively; unloaded bench tests aren’t a reliable measure of functionality.

4. Uncertainty Around Effectiveness After Track/Extended Use

There are a few anecdotal threads (not massive data) on BMW forums where long‑term or track‑used Wavetrac units seemed less effective over time (e.g., perceived reduction in torque biasing). This isn’t a documented product recall, but owners in other BMW contexts have discussed it: if the differential isn’t engaging as before after heavy use, it can be due to fluid breakdown, internal wear, or install‑related backlash shift.