E46 M3 SMG resistor mod

A common modification that is often done is the "resistor mod" we are going to break the myth behind this so called "mod"

     What it boils down to is the additional heat is being generated by the electric motor overworking itself and not internal engine temps. there are a few scenarios in which you might reach this threshold

1- Increased loading of smg system, at racetrack etc. in which you are asking the smg system to shift gears back and fort in rapid succession for long periods. this increases the on time of motor and heat associated with it not being able to cool down.

2-Electric motor bearings are dry causing additional strain on electric motor. The seizing bearings cause motor to use more power to overcome additional friction and increases on time of motor as it cannot run at high rpm due to increased resistance.

     What the resistor mod does is reduce the true temperature reading from getting to the control module, the control module does not trip any lights because it has no idea of what i really going on.

yes this is a quick fix and it will most likely get you going for a few months but it is not a conclusive repair. the system does not like running that hot as fluid is not designed for that type of running temp, you will also have more leak-down of pressure and thus more on time of motor. this reduces life of motor even further.

Here is what we suggest

Type 1

Because you most likely are having this problem during track days. adding ducting to get more cool air to pump or physical relocation of pump to an area(trunk/drug bin) in which it has access to cooler ambient temps.

Type 2

You really need a new or rebuilt electric motor, if you are in early stages the resistor mod will give you about 6-12 months of driving after that  you should start crossing your fingers. At minimum review the motor performance it is possible that bearings are seizing up.

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