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6 Speed Manual Conversion for S85

We’ve all been there. You’re ready to take off at the red light, you lift your foot off the brake, press the gas—and then… nothing.

A red cog! THE red cog of death for these cars. Almost as bad as having your rod bearings grenade your engine.

Don’t get me wrong, there’s absolutely no issue with the 7-speed automatic in terms of driving experience and gear-snapping excitement. The SMG 3 (Sequential Manual Gearbox) was a major part of the M5’s initial launch in 2005, and even today, it still holds its place inside these engineering marvels. But the downside? Reliability issues when pushing these cars into their second and third lives. Rebuilding the internals, rewiring frayed harnesses, and replacing worn components are a must if you’re thinking about the long-term durability of these transmissions. While BMW’s focus was on creating a single-clutch, manual-like but automatic transmission, the durability of the SMG 3 has proven to be a challenge, especially for those who push these cars hard or plan to keep them for the long haul.

BMW revolutionized the driving experience by pushing the boundaries of automated shifting, offering an exhilarating drive with the SMG 3. However, as time went on, reliability concerns began to surface, making it clear that there were trade-offs. So, what can you do if your SMG 3 is starting to show its age?

 

Rebuilding the SMG 3: A Viable Option

 

Before considering other options, it’s important to know that a full rebuild of the SMG 3 transmission is a viable solution for many owners. Restoring the SMG can be an excellent

way to preserve the factory setup and maintain the sought-after driving experience. However, it’s essential to understand that this rebuild can’t be accomplished using only OEM parts. While transmission internals such as the clutch, throw-out bearing, slave cylinder, fork, sleeve, plastic pin, metal clip, and flywheel are available through BMW, key hydraulic components like the hydraulic pump and its internals are not sold individually. Instead, the hydraulic unit—including the electric motor, hydraulic pump, pressure accumulator, clutch valve solenoid, oil reservoir, and pressure and temperature sensors—are sold as a complete assembly new from BMW.

Rebuilding the SMG system is a complex and intricate task that requires expert knowledge of the system. Whether performed in-house or by professionals, the rebuild must be executed with precision to meet BMW’s strict standards.

 

A Light at the End of the Tunnel: 6-Speed Manual

 

Alternatively, there is a light at the end of the tunnel—a true escape from the complexities and potential headaches of an SMG rebuild. Imagine yourself fully in control of your German V10 sedan, rowing through the gears with that raw, mechanical connection between you and the engine. This is the ultimate driving experience. And while the SMG 3 may have been groundbreaking in its time, for many drivers, the pure joy of a 6-speed manual is unmatched.

This is where we come in. We specialize in both repairing the SMG 3 and converting your car to a 6-speed manual—giving you the flexibility to choose the option that best suits your driving desires. We offer both services, and we take pride in making sure that whether you’re restoring your SMG 3 to its original state or switching to a 6-speed manual, you’re getting the highest quality work.

For those who prefer to rebuild their SMG 3, we provide expert services that adhere strictly to BMW’s factory standards, ensuring your transmission is as reliable as the day it was first installed. But if the manual experience calls to you, we can also help convert your car to a full 6-speed manual transmission, delivering that classic, tactile driving experience that only a manual can offer.

Our priority is your satisfaction and the long-term performance of your vehicle. Whether you choose to repair or convert, we ensure that every project is completed with the same precision and care that BMW put into these machines when they first rolled off the production line.

 

The 6-Speed Manual Swap: Journey Starts Now

 

Our journey to convert our M5 E60 from an automated manual transmission (SMG) to a fully functional 6-speed manual transmission starts now. When these cars were first sold, BMW did give first owners the chance to spec their M5 or M6 with stick. However, the choice was relatively rare—allegedly, only about 1 in 10 owners opted for it. While most cars came equipped with the SMG system, every E60, E61, E62, and E63 chassis was designed to accommodate the 6-speed manual.

The transmission we use for this swap is the GS6-53BZ, the same unit that was offered in the manual S65-powered M3 models (E90 and E92). It’s the exact same transmission as what was available in the M5 and M6, but some adjustments are needed to make it fit and function properly in the S85-powered models.

While the GS6-53BZ transmission itself is identical across the M3 and M5/M6, with the same bellhousing and bolt patterns, there are key differences in the transmission mounts, clutch, slave cylinder, and even the removal of the oil cooler. These changes ensure that the transmission functions and fits as intended in the M5, with all parts working in harmony.

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The 6-Speed Manual Swap: Preventive Maintenance
 

The process of installing a new 6-speed manual transmission begins by carefully removing the existing transmission and related components to make room for the new setup. This involves disconnecting and removing the exhaust system, driveshaft, flywheel, and the Transmission Control Unit (TCU). Each component is carefully detached to ensure everything is in proper condition for the new transmission, with minimal disruption to the surrounding systems.

With the car disassembled, we take full advantage of this opportunity to perform essential preventive maintenance. If any of the following components are still original, this is the ideal time to replace them to avoid future failures down the road. We begin with the rear main seal, which can wear over time and lead to oil leaks. The crankcase ventilation valves, known to fail with age, should also be replaced to maintain engine efficiency. Exhaust gaskets and bushings which degrade over time, are inspected and replaced as needed.

The rear subframe bushings are a particularly crucial area. Over time, these bushings become prone to drying out and cracking, an issue that can be exacerbated when converting to a manual transmission. The added stress during hard launches can place significant strain on these worn bushings, potentially leading to damage of the subframe’s differential mounting tabs. BMW has updated these bushings over the years, with the newer versions offering improved cushioning and durability. Replacing these bushings and/or reinforcing the subframe may be necessary if significant wear or damage is detected.

We also address driveline components by replacing the center bearing and guibo, as well as servicing the differential oil and replacing both the transmission oil and filter. Fresh fluids in the transmission and differential ensure that all moving parts are lubricated and protected for optimal performance. In addition, we inspect the clutch master and slave cylinders, replacing them as necessary to ensure smooth, reliable engagement with the new manual transmission.

Since the transmission we are installing is new to us, it’s critical to inspect its condition before installation. If a brand-new assembly hasn’t been purchased, we recommend a thorough gearbox housing rebuild. This involves inspecting key components, such as the guide sleeve, shaft seals, and breather tube. These parts are much easier to replace with the transmission out of the car, ensuring the housing is fully sealed and free of any potential issues that could arise once everything is reassembled. Components like the backup light switch, cover lid, and torx screws are also checked and replaced if necessary to ensure everything is in optimal working order.

Once all the components are removed and inspected, we perform a meticulous review of the surrounding systems. This final inspection ensures that all related systems—such as the driveline, suspension, and other critical areas—are in excellent condition. With everything ready, the car is fully prepared for the new transmission installation, ensuring it performs at its best for years to come.

Important Reminder Before Ordering Parts

As you review the part list for your conversion, please keep in mind that sourcing the right components is crucial for achieving a seamless and high-quality manual swap. We recommend getting in touch with us before purchasing any parts, as we have many essential components in stock and are ready to guide you through the process. We’ll help ensure that you get the most effective and cost-efficient approach to successfully complete your conversion. Reach out to us today to discuss your project and let’s make sure your car gets the care and attention it deserves!

The 6 Speed Manual Swap: Interior Modifications
 

When converting your BMW M5 or M6 from the SMG transmission to a 6-speed manual, it’s not just about swapping out the gearbox. The interior also requires modifications to accommodate the new shifter and related components. This process ensures that the car maintains its functional and aesthetic integrity, achieving an OEM+ look while optimizing the driving experience.

 
Center Console Trim
 

One of the most noticeable changes during the manual conversion is the Center Console Trim. The original trim, designed for the SMG setup, must be replaced to accommodate the manual shifter. Whether aluminum or wood, the new trim ensures a clean, snug fit for the manual transmission and integrates seamlessly into the interior.

Along with the new center console trim, the Oddments tray below the console is also updated. Originally, this tray featured a retractable cover that exposed only the ashtray and lighter outlet, with no other buttons inside. With the manual setup, the retractable cover is replaced by a new, fixed plastic storage tray. This new tray retains the lighter outlet and now features a holder for the EDC Button. This change removes the only ashtray from the front center console.

PRE-LCI Manual M5/M6 E6X Center Console Trim Assembly Part Number:  51168037228

Includes: PRE-LCI Manual M5/M6 E6X Oddments Tray Part Number:  51168037213

Quantity: 1

Alternatively, if you choose the LCI Manual Setup option discussed later, the ashtray is relocated to a new drawer beneath the radio. In this case, a different Oddments tray without the lighter outlet is required, as the outlet will now be present in the newly located drawer. It’s important to keep this in mind when planning your conversion, as this choice affects both the functional layout and the overall appearance of the center console.

LCI Manual M5/M6 E6X Center Console Trim Assembly Part Number:  51167903537

Includes: LCI Manual M5/M6 E6X Oddments Tray Part Number:  51168045434

Quantity: 1

 
SZM Switch Module
 

A crucial part of the manual conversion involves updating the SZM (SteuerZentrale Modul) switch setup. The SZM controls multiple interior functions, including seat heating, ventilation, and driving modes like MDM (M Dynamic Mode) and DTC (Dynamic Traction Control). During the conversion, we’ll relocate the MDM/DTC button from the original SMG 3 Shifter Surround Trim to the new SZM switch setup, ensuring that these controls remain easily accessible and functional.

The SZM is also responsible for managing seat functions, so we must source the right module based on your car’s specific configuration. All M5 and M6 models come with heated seats as standard, and most also feature ventilated seats. If your car has them, we’ll ensure the new SZM supports this function. For vehicles with only heated seats, we’ll opt for an SZM without ventilation controls.

Additionally, all M5 models come equipped with cornering bolsters as part of the seat setup. We’ll source the appropriate SZM from a Manual M variant to ensure full compatibility with this feature, which is essential for proper seat function.

By sourcing and installing the correct SZM, we’ll make sure that all seat functions, including MDM/DTC button relocation.

As many of the components for this swap are no longer in production, sourcing parts from a Manual S85 (used market) can be crucial for achieving the right look. Finding the right buttons, switches, and connectors ensures a factory-like finish while making sure your M5 or M6 operates exactly as BMW intended. This is an important step to maintain the car’s original functionality and preserve that OEM+ aesthetic.

PRE-LCI Manual M5/M6 E6X SZM Switch Module Part Number:  N/A

Quantity: 1

 
LCI Manual Setup
 

When undertaking a manual conversion, the choice between an LCI and non-LCI setup may seem straightforward at first. However, in our latest conversion, we found ourselves pivoting toward LCI components—not out of personal preference, but due to the significant challenges we encountered in sourcing the necessary parts. This wasn’t the case in previous conversions, where non-LCI parts were more readily available. As availability continues to shift, what was true before may not always apply now. If you’re considering a manual swap, it’s important to get in touch with us beforehand so we can guide you based on the current parts landscape and help you make an informed decision before moving forward.

Faced with these challenges, we pivoted to an LCI manual conversion, which proved to be the more feasible option. While the updated trim did provide a fresh aesthetic, the main reason for this shift was the increased availability of LCI parts. Components like the ECU Switch (Electronic control unit) and its 32-pin connector (X16919), along with the left and right Switch Block Buttons and their respective 3 pin connectors (X17257 for left, X17259 for right), were significantly easier to source. This allowed us to maintain the vehicle’s functionality while completing the swap within a shorter timeframe.

That said, transitioning to LCI components comes with its own set of unique challenges. The shift isn’t just about sourcing parts—it also requires rewiring and modifying components to ensure everything fits properly. One of the major changes is the replacement of the CCC (Car Communication Computer) from the pre-LCI system with the newer CIC (Car Information Computer) in the LCI models. This swap involves updating holders and other parts such as the menu button and its wiring.

Furthermore, the MDM/DTC button functionality, needs to be relocated as part of the shift to the new Switch Block Buttons setup, adding complexity to the rewiring process.

For more details on the LCI conversion process, including the changes to the CIC, menu button, and other components, please refer to our M Service : Center Console Retrofit for S85 page: [Link coming soon].

LCI Manual M5/M6 E6X ECU Switch (Electronic control unit) Part Number:  61319183228

Does not include required connector: X16919 (32 PIN)

Quantity: 1

LCI Manual M5/M6 E6X Switch Block Buttons S839 (Left) Part Number:  N/A

Does not include required connector: X17257 (3 PIN)

Quantity: 1

LCI Manual M5/M6 E6X Switch Block Buttons S840 (Right) Part Number:  N/A

Does not include required connector: X17259 (3 PIN)

Quantity: 1

 
The Final Touches
 

At this stage of the manual conversion, the manual transmission and essential functions are fully operational. However, it’s important to note that the center console retrofit for the S85 isn’t entirely complete yet. While the interior now accommodates the manual setup, further work, such as integrating the updated infotainment system, is still required. To fully finalize the retrofit, additional steps, including rewiring the CIC system and relocating controls, need to be completed. This ensures the car’s functionality and aesthetic are fully in line with modern standards.

If you’re ready to take your BMW M5 or M6 to the next level with a manual transmission conversion or any additional interior modifications, we’re here to help. Reach out to us today to get started and make your car truly your own.

Comparison of SMG 3 / Pre-LCI Manual / LCI Manual Setups
E60 SMG 3 PRE-LCI
E60 MANUAL PRE-LCI W/ E6X SHIFTER
E60 MANUAL LCI W/ F1X SHIFTER
Steering Wheel

As part of the manual transmission conversion, the steering wheel requires an upgrade. The shift paddles, which were originally mounted to the SMG steering wheel, must be removed, leaving holes in the wheel itself. This means a replacement steering wheel is necessary to ensure a clean, functional finish.

BMW offered two steering wheel options for manual M vehicles: one with heating capability and one without. Both options are listed below:

1. Manual M5/M6 E6X Steering Wheel (Non-Heated) Part Number: 32342283933

1. Manual M5/M6 E6X Steering Wheel (Heated) Part Number: 32342283937

Quantity: 1

 

If your current steering wheel lacks heating but you would like to add this feature, the retrofit involves more than just the wheel replacement. In addition to the new steering wheel, a new Switch Unit Steering Column, Coil Spring Cartridge, and custom wiring are required.

We can assist with this retrofit to integrate the heated steering wheel seamlessly into your M5 or M6.

For more details, visit our M Service: Heated Steering Retrofit for S85 page: [Link coming soon].

 

Manual part list:

Shifter Carrier
1. Shifter Arm

Manual M5/M6 E6X Part Number: 25112283195

Quantity: 1

2. Bushing

Manual M5/M6 E6X Part Number: 25117507695

Quantity: 2

3. Bearing Bolt (Right)

Manual M5/M6 E6X Part Number: 25117529078

Quantity: 1

4. Bearing Bolt (Left)

Manual M5/M6 E6X Part Number: 25117529079

Quantity: 1

5. Shifter Arm Bushing

Manual M5/M6 E6X Part Number: 25111222015

Quantity: 1

6. Shift Lever

Manual M5/M6 E6X Part Number: 25117527262

“Shorter” 545i/645i E6X Part Number: 25117546373

Quantity: 1

7. Shift Lever Bearing

Manual M5/M6 E6X Part Number: 25111220600

Quantity: 1

8. Rubber Booth

Manual M5/M6 E6X Part Number: 25117519775

Quantity: 1

9. Selector Rod

Manual M5/M6 E6X Part Number: 25112283217

Quantity: 1

10. Securing Clip

Manual M5/M6 E6X Part Number: 25117571899

Quantity: 2

11. Gearshift Rod Joint

Manual M5/M6 E6X Part Number: 25117526415

Quantity: 1

12. Lock Ring

Manual M5/M6 E6X Part Number: 25111222451

Quantity: 1

13. Dowel Pin

Manual M5/M6 E6X Part Number: 23411466134

Quantity: 1

Shifter Carrier Assembly Reference
Clutch Hardware
1. Clutch Kit

Manual M5/M6 E6X Part Number: 21212283648

Includes clutch, pressure plate, throw out bearinng, pilot bearing, alignment tool.

Quantity: 1

2. Release Bearing

Manual M5/M6 E6X Part Number: 21517548396

Included in 1. Clutch Kit

Quantity: 1

3. Clutch Bolt

Manual M5/M6 E6X Part Number: 21207548052 (M8X18)

Replacement not required.

Quantity: 6

Manual M5/M6 E6X Part Number: 07129905539 (M6X50)

Quantity: 9

4. Fork Lever

Manual M5/M6 E6X & M3 E9X Part Number: 21511204229

Replacement not required.

Quantity: 1

5. Spring Clip

Manual M5/M6 E6X & M3 E9X Part Number: 21517570284

Replacement not required.

Quantity: 1

6. Ball Pin

Manual M5/M6 E6X Part Number: 21511223328

“Improved” AGA Part Number: AGACPP223328

Quantity: 1

Clutch Hardware Reference
Gearbox Mounting
1. Gearbox Support

Manual M5/M6 E6X Part Number: 22312282027

Replacement not required use the Gearbox Support from your SMG 3.

Quantity: 1

2. Mount Bushing

Manual M5/M6 E6X Part Number: 22312283285

Quantity: 2

3. Hex Nut

Manual M5/M6 E6X Part Number: 07129904862

Replacement not required.

Quantity: 2

4. Hex Nut

Manual M5/M6 E6X Part Number: 22316760944

Replacement not required.

Quantity: 2

5. Hex Bolt

Manual M5/M6 E6X Part Number: 22326760945

Replacement not required.

Quantity: 6

6. Supporting Bracket

Manual M5/M6 E6X Part Number: 22316776524

Replacement not required use the Supporting Bracket from the GS6-53BZ.

Quantity: 1

7. ASA-Bolt

Manual M5/M6 E6X Part Number: 07129905738

Replacement not required.

Quantity: 4

 

Gearbox Mounting Reference
Gearbox Housing (not required)
1. Guide Sleeve

Manual M5/M6 E6X Part Number: 23117537909

Replacement not required.

Quantity: 1

2. Torx Screw

Manual M5/M6 E6X Part Number: 23117531355

Replacement not required.

Quantity: 4

3. Shaft Seal

Manual M5/M6 E6X Part Number: 23127501712

Replacement not required.

Quantity: 1

4. Cover Lid

Manual M5/M6 E6X Part Number: 23117537911

Replacement not required.

Quantity: 1

6. Screw Plug Gasket

Manual M5/M6 E6X Part Number: 23117531356

Replacement not required.

Quantity: 2

7. Shaft Seal

Manual M5/M6 E6X Part Number: 23121282458

Replacement not required.

Quantity: 1

8. Breather Tube

Manual M5/M6 E6X Part Number: 23117537913

Replacement not required.

Quantity: 1

9. Shaft Seal

Manual M5/M6 E6X Part Number: 23128677736

Replacement not required.

Quantity: 1

10. Backup Light Switch

Manual M5/M6 E6X Part Number: 23147524811

Replacement not required.

Quantity: 1

Gearbox Housing Reference
Clutch Control:
1. Input Cylinder

Manual M5/M6 E6X Part Number: 21526777344

Quantity: 1

3. Grommet

Manual M5/M6 E6X Part Number: 21526771100

Quantity: 1

4. Hose

Manual M5/M6 E6X Part Number: 21521163714

Brake hose, sold by the meter.

Quantity: 1

6. Clutch Line Repair Kit

Manual M5/M6 E6X Part Number: 21521165451

Quantity: 1

7. Clutch Hardline

Manual M5/M6 E6X Part Number: 21526760828

Quantity: 1

8. Clutch Softline

Manual M5/M6 E6X Part Number: 21526774226

Quantity: 1

9. Bracket Clutch Softline

Manual M5/M6 E6X Part Number: 21526774228

Quantity: 1

10. Grommet

Manual M5/M6 E6X Part Number: 21521164603

Quantity: 1

11. Pipe

Manual M5/M6 E6X Part Number: 21527839306

Quantity: 1

12. Lockvalve

Manual M5/M6 E6X Part Number: 21521165343

Quantity: 1

13. Slave Cylinder

Manual M5/M6 E6X Part Number: 21526775924

Quantity: 1

14. Hex Nut Locking

Manual M5/M6 E6X Part Number: 07129904002 or 07129906196

Quantity: 2

15. Knurled Bolt

Manual M5/M6 E6X Part Number: 21511203012

Quantity: 2

16. Clutch Switch

Manual M5/M6 E6X Part Number: 35426876898

Quantity: 1

17. Grommet

Manual M5/M6 E6X Part Number: 21521163894

Quantity: 1

Clutch Control Reference
Pedal Assembly:
7. Fuse Clip

Manual M5/M6 E6X Part Number: 07129904567

Quantity: 1

9. Pedal

Manual M5/M6 E6X Part Number:  35311161586

Quantity: 1

10. Bushing

Manual M5/M6 E6X Part Number: 35211158290

Quantity: 2

11. Pin

Manual M5/M6 E6X Part Number: 35306759942

Quantity: 1

12. Pin Master Cylinder

Manual M5/M6 E6X Part Number: 21526759940

Quantity: 2
13. Metal Pin Master Cylinder

Manual M5/M6 E6X Part Number: 21521161729

Quantity: 1

14. Return Spring

Manual M5/M6 E6X Part Number: 35311165749

Quantity: 1

15. Rubber Pad

Manual M5/M6 E6X Part Number: 35211108634

Quantity: 1

16. Compression Spring

Manual M5/M6 E6X Part Number: 35311165566

Quantity: 1

18. Bracket Compression Spring

Manual M5/M6 E6X Part Number: 35301164381

Quantity: 1

19. Pin

Manual M5/M6 E6X Part Number: 35311161721

Quantity: 1

20. Circlip

Manual M5/M6 E6X Part Number: 07119905695

Quantity: 1

21. Bracket Compression Spring

Manual M5/M6 E6X Part Number: 35311161719

Quantity: 1

22. Pin

Manual M5/M6 E6X Part Number: 35306759929

Quantity: 1

23. Stop Buffer

Manual M5/M6 E6X Part Number: 35306759939

Quantity: 1

21. Bracket Compression Spring

Manual M5/M6 E6X Part Number: 35311161719

Quantity: 1

Pedal Assembly Reference
Other Parts
9. Wiring Harness

Manual M5/M6 E6X Part Number:  23017840637

Quantity: 1

10. Clip

Manual M5/M6 E6X Part Number: 12521437136

Quantity: 3

 

Wiring Harness Reference
1. Flywheel

Manual M5/M6 E6X Part Number: 21212283060

“Lighter”  Manual M3 E9X Part Number: 21212283820

Quantity: 1

2. Ball Bearing

Manual M5/M6 E6X Part Number: 11211720310

Quantity: 1

3. Dowel Pin

Manual M5/M6 E6X Part Number: 11211736881

Quantity: 1

Flywheel Reference
1. Drive Shaft

Manual M5/M6 E6X Part Number: 26112283210

SMG 3 L=1526MM / Manual L=1557MM

Custom made to order in metal or carbon fiber.

Quantity: 1

Drive Shaft Reference
1. Shift Knob (Illuminated)

Manual M5/M6 E6X Part Number: 25112283015 or 25112283080

“Newer” Manual M5/M6 F1X Part Number: 25112284205 and requires: 25117565871

Quantity: 1

2. Foam Insert

Manual M5/M6 E6X Part Number: 25117521447

Quantity: 1

3. Connector

Manual M5/M6 E6X Part Number: N/A

Custom made to order wiring with OEM connectors.

Quantity: 1

Shift Knob Reference