Third Gear

2013 BMW 128i 2D Convertible, Eng CD N52, Standard TransSECTION Third Gear
WARNING: This page does not describe the selected car, but rather 212 other vehicles, including the 2012 BMW 750i, 2012 BMW 750Li, 2011 BMW M3, 2011 BMW 750i, and 2011 BMW 750Li. However, it is still accessible from the selected car via links, so may be relevant.

Drive torque is applied to the torque converter impeller and transferred to the turbine. See Fig 1. The turbine shaft rotates clockwise (CW). The "A" clutch and the "B" clutch are locked, this causes the rear input ring gear to be locked to the sun gear in the Simpson Gear set. The Simpson gear set is locked in a 1:1 ratio. The "E" clutch is locked which locks the ring gear to the sun gear in the Simpson gear set. The entire transmission planetary system is now locked in a 1:1 ratio. Freewheel "H" is overrun and freewheel "J" is not used. Freewheel "K" continues to be locked.

Fig 1: Power Flow Schematic In Third Gear
G00317048Courtesy of BMW OF NORTH AMERICA, INC.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
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  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.