When the stock lower motor starts to fail you will notice a sort of disconnect from the engine as it will feel like it is doing its own thing and will start to transmit a TON of vibration through the cabin. BSH has a great option for upgrading this part instead of using the factory part.

Fit these MINI models:
Gen1 MINI:
R50: 2002-2006 Hatchback: Cooper
R52: 2004-2008 Convertible: Cooper and Cooper S
R53: 2002-2006 Hatchback: Cooper S

Gen2 MINI:
R55: 2008-xxxx Clubman: Cooper and Cooper S
R56: 2007-xxxx Hatchback: Cooper and Cooper S
R57: 2009-xxxx Convertible: Cooper and Cooper S
R58: 2011-xxxx Roadster: Cooper and Cooper S
R59: 2011-xxxx Coupe: Cooper and Cooper S