The brief
Mr Xavier brings his M5 in for its full maintenance servicing on a regular basis, and this time he mentioned he'd been feeling some vibration whenever the gear engaged. That's exactly the kind of thing the multi-point inspection catches. The gearbox sits on a rubber mount that carries its weight and absorbs the shake, keeping it out of the cabin. As the rubber ages it sags and cracks, and once it does the gearbox moves around more than it's meant to, so the vibration comes straight through, worst at the moment a gear takes up the drive and the load shifts. On a car with an M5's torque the mounts work hard, and a worn one only gets worse, so it needs changing for a fresh genuine part.
The diagnosis
The multi-point inspection and a comprehensive safety check went through everything, and on the lift the gearbox mount got a pry-test, the rubber cracked and the mount sunk with play under load, which is exactly what makes that vibration when the gear engages. The engine mounts and the rest of the drivetrain checked out at this point. That's a gearbox mount replacement, you renew the worn mount with the genuine part, so the call was a new genuine BMW transmission mount.
The work
The gearbox was taken onto a transmission jack to take its weight, the worn mount removed, and a new genuine BMW transmission mount fitted, every fastener torqued to the manual figures, with the gearbox checked sitting square before it was let down to load onto the fresh mount. A road test confirmed the vibration on gear engagement was gone, the drivetrain smooth and settled.
The outcome
Smooth gear engagement with no vibration, the drivetrain settled, and the M5 back to feeling the way it should. The car went home with the gearbox properly supported again. A worn transmission mount only sags further and feeds the shake straight into the cabin, so renewing it with the genuine part reset it, exactly the kind of thing a regular inspection is for.
