Conversion of the BMW SMG Transmission

BMW’s E46 M3 is arguably the best //M car to date.

A high revving straight-six with beautifully tuned individual throttle bodies, boasts an impressive 333hp, with nimble handling, an aggressive stance, and body design that still competes with today’s exotic cars. Unfortunately, and at many owners’ expense, it had one major downfall; The SMG transmission

The BMW SMG transmission is a sequential manual gearbox that was first introduced in the early 2000s. It was offered as an option on many different BMW models and provided drivers with a unique driving experience, however, some drivers found the SMG transmission to be difficult to use, and eventually, it was discontinued.

In this article, we will discuss everything you need to know about the BMW SMG conversion to manual transmission. Also, we will cover everything from the benefits of changing the SMG transmission to Manual to the cost of performing the conversion, including important tips when driving.

Whether you are just curious about this process or you are ready to make the switch, keep reading to learn more!

The Benefits of Converting the BMW SMG to the Manual 6spd Transmission

There are many benefits to converting your BMW SMG transmission to a manual transmission. Perhaps the most obvious benefit is that you will have much more control over your car when driving; We give control back to the driver!

We have extensive experience swapping the SMG transmission to its highly desired, 6-speed counterpart. The best news is, we can use the transmission that’s already in the car, eliminating the cost of buying a new or used transmission.  When BMW built the SMG transmission option they basically bolted on several electronically controlled hydraulics. To prevent overworking or premature failure of the hydraulic components, they removed a few internal shifting parts of the transmission.

Once the driver decides they have had enough of the SMG transmission (usually when the hydraulic pump fails and they are facing a $3k plus repair) they drop the car off for the swap!

The Cost of having the Conversion Completed

The cost of a BMW SMG conversion to manual transmission will vary depending on the specific model and year of your car. However, in general, the cost of the conversion should be about $4000 and will take 5 to 7 days to complete. This may seem like a large expense, but it is important to remember that this is a permanent change. Once you have converted your car to a manual transmission, you will wonder why you waited so long to get it done!

How to go about the BMW SMG Transmission Conversion

To explain the process briefly, We begin by removing the transmission, driveshaft, the old hydraulics, the old shifter, and paddles, including all wiring that will no longer be used.

Next, we install the new parts needed for the manual transmission. We have to cut out the plate that blocks the shift lever hole and weld in the bracket that holds the rear shift lever bushing. Secondly, we install the clutch pedal, shift lever, and return springs. Note: we can install the shift boot and shift knob as chosen by the owner. Next, the clutch pedal switch is wired in. We find the factory knockouts for the clutch hydraulic lines and run the lines to and from the new master cylinder.

We set the transmission up on the bench. Remove the bellhousing portion, disassemble the shift rod holder and clean the housing. We cover the bearing and then drill two holes for the new shift detents. We press a small bearing onto the shift rod holder for the new detents to ride on. Next, install a return spring to center the assembly when the shifter is put into neutral. We have to machine two grooves for the snap rings, then drill one last hole for the spring to rest on and install a specially machined pin.

Now that that’s done, we clean the bellhousing, thoroughly put grease on the new components, and reassemble everything. We take special care to be sure everything is properly lined up and sealed!  With the transmission reassembled, we have to thread the hole at the back of the transmission that holds the new gear recognition switch. This new switch also uses a different detent, spring, and pin. That finalizes the transmission work! Before we reinstall the transmission, we must remove the clutch and determine whether it needs replacement or just to be reset.

Assembly from this point is the same as installing the regular 6-speed transmission. We install a new slave cylinder and line, then hook up the new shifter. We reassemble the driveline exhaust, heat shields, and the rest of the underbody.

When the swap is complete, the drivers, passengers and any other onlookers will have no idea the car was ever equipped with the dreaded SMG transmission

Important Info about the SMG to Manual Conversion:

The swap requires some wiring. The wiring isn’t very straightforward. Different model years with different options require different wiring strategies. Simply comparing wiring diagrams between SMG and 6-speed models lets us know what to do!

The same goes for coding, different years have different requirements, although we know we will always need to re-code the DME (digital motor electronics) and instrument cluster.

During the entire process, we check any related components for failure or wear, such as the transmission mounts or the guibo.

Returning the SMG Parts to the Customer

Once the conversion is complete, we will carefully reassemble the car and return it to you. We will also return all of the SMG parts that were removed from your car. This includes the SMG gearbox, wiring harnesses, oil pressure parts, filters, and hoses.

One Driving Tip for your New Manual Transmission

Important Fact: The break-in period is subject to the driving environment and road conditions.

So, what do you think? Are you interested in converting your BMW SMG transmission to a manual? If so, be sure to consult with our experienced, BMW Service Team here at Eurompire by calling us at (704)777-0006, or email us at We are ready to assist you in getting your SMG shifting problems fixed and your BMW back on the road today!

-The team at Eurompire