The Ultimate Guide to Manual Conversion on a BMW E46: Parts You Need, Recommended Upgrades, and Wiring

The Ultimate Guide to Manual Conversion on a BMW E46: Parts You Need and Recommended Upgrades

Converting your BMW E46 from automatic to manual is one of the most rewarding upgrades you can make. Not only does it enhance the driving experience, but it also increases the value of your vehicle. This guide will outline all the essential parts you need for the conversion and recommend some upgrades to consider while you're at it.

Essential Parts for the Manual Conversion

1. Manual Transmission (Getrag or ZF)

   • Ensure it's compatible with your specific E46 model.

2. Manual Transmission Crossmember

   • Different from the automatic version, so make sure you have the correct one.

3. Manual Driveshaft

   • The length varies between different models, so get one that fits your E46.

4. Flywheel

   • Dual-mass or single-mass flywheel; single-mass is often preferred for performance.

5. Clutch Kit

   • Includes the clutch disc, pressure plate, and release bearing.

6. Clutch Pedal Assembly

   • Complete pedal set with brackets and hardware.

7. Clutch Master Cylinder

   • Necessary for the hydraulic system.

8. Clutch Slave Cylinder

   • Works in conjunction with the master cylinder.

9. Clutch Line

   • Connects the master cylinder to the slave cylinder.

10. Manual Transmission Mounts

    • Ensure they are in good condition or replace with upgraded mounts.

11. Shift Linkage and Selector Rod

    • Manual-specific linkage for proper gear selection.

12. Shift Knob and Boot

    • For the complete manual feel.

13. Brake Pedal (Manual)

    • Shorter than the automatic version.

14. Transmission Fluid

    • Ensure you have the correct type and quantity.

15. ECU or DME (Manual)

    • You may need a reflash or a manual-specific ECU.

16. Rear Differential

    • Ratios may differ; upgrading to a manual-compatible differential is recommended.

Recommended Upgrades During the Conversion

1. Lightweight Flywheel

   • Improves engine response and acceleration.

2. Performance Clutch Kit

   • For better handling of increased power and spirited driving.

3. Short Shifter Kit

   • Reduces shift throw for a sportier feel.

4. Dual Shear Selector Rod (DSSR)

   • Eliminates play in the shifter, providing more precise shifts.

5. Upgraded Transmission Mounts

   • Polyurethane or solid mounts for improved stability.

6. Stainless Steel Clutch Line

   • More durable and provides a better clutch feel.

7. Upgraded Differential Bushings

   • Polyurethane bushings reduce flex and improve power transfer.

8. Guibo (Flex Disc)

   • Upgrading to a stronger guibo can handle increased torque and reduce drivetrain slack.

9. Center Support Bearing (CSB)

   • Replacing this bearing ensures smoother power delivery and reduces vibrations.

10. New Seals and Gaskets

• Replace transmission seals, rear main seal, and any other gaskets to prevent leaks.

Wiring Instructions

One of the more challenging aspects of a manual conversion is handling the wiring. Here’s a step-by-step guide to help you navigate this part of the project.

1. Neutral Safety Switch Bypass

   • The automatic transmission has a neutral safety switch that prevents the car from starting unless it's in Park or Neutral. For a manual conversion, you need to bypass this switch.

   • Locate the automatic transmission wiring harness. Find the two wires connected to the neutral safety switch (usually black or black/white). Connect these wires together to bypass the switch.

2. Reverse Light Wiring

   • The manual transmission has a reverse light switch that you need to wire into your existing harness.

   • Locate the reverse light wiring on the manual transmission. Typically, this involves two wires (often blue and green).

   • Splice these wires into the existing reverse light wiring from your automatic harness. Ensure the connections are secure and insulated.

3. Clutch Switch Installation

   • The clutch switch ensures the car starts only when the clutch is depressed.

   • Mount the clutch switch on the clutch pedal assembly. Connect the switch to the wiring harness using the appropriate connectors (refer to your E46 manual for the specific wiring colors).

4. Reprogramming or Reflashing the ECU

   • The ECU from an automatic car needs to be reprogrammed to function correctly with a manual transmission.

   • This can be done through specialised software or by sending the ECU to a professional for reprogramming. Ensure it’s set to recognise the manual gearbox.

5. OBDII Coding

   • Use OBDII coding tools to update the car’s configuration. This step is essential to clear any error codes and ensure the car's systems recognise the manual transmission.

Installation Tips

• Consult a Professional: If you're not confident in your mechanical skills, it's best to consult or hire a professional for the conversion.

• Gather All Parts First: Ensure you have every part before starting the conversion to avoid delays.

• Follow a Detailed Guide: Use a step-by-step guide specific to the E46 for reference.

• Inspect and Replace Worn Components: While you have access, inspect and replace any worn or damaged components.

• Test Thoroughly: After the conversion, test the vehicle thoroughly to ensure everything functions correctly.

Conclusion

Converting your BMW E46 to a manual transmission is a significant project that can greatly enhance your driving pleasure. By gathering all the essential parts and considering the recommended upgrades, you can ensure a smooth and successful conversion. Remember, this guide is a starting point—always do your research and consult with professionals if needed. Happy driving!

Ready to transform your E46? Contact us at Garage46 for expert advice and top-quality parts. Let's make your driving dreams a reality!