Do the M3 and ZA for share the same gearbox? below was interesting reading............
The E46 M3 uses "exactly" that same gearbox as the manual cars. The only difference is a hydraulic selector unit mounted on top of the gearbox where the manual car's gearstick would normally enter. There can be issues with the hydraulic pump unit, these tend to be the only things that will go with the SMG cars and are not cheap! To buy one, it's almost £1000!!! I have replaced one myself so don't know how much a garage would charge to supply and fit? It is important that the software is updated annually, if not at each service. The SMG software measures clutch wear by determining where it finds the biting point. If this is not updated as the clutch wears, then the car thinks the clutch biting point is where it was, at for instance, new. This then causes the car to be a bit jerky and can affect how the car drives at it changes gear. Differentials also took a beating on the SMG cars if they were driven, shall we say, enthusiastically!!! If the car is driven on track, or even on the road in S6 mode, traction off, the quickness of the gearchange and the torque transfered creates a large bang, as some of you will know, which causes premature wear on the differential. Also if the launch control has been used a few times it does take it's toll on the clutch. I am sure this information is stored on the ECU and a dealer, or someone with the appropriate diagnostic equipment, can tell how many times it's been used.
