Defects in 1999-2005 BMW 3 series
It seems that lately there are a lot of claims concerning defects in BMW 3 series vehicles manufactured between 1999 and 2005. It looks like the BMW 3 Series vehicles manufactured during this time period may contain a manufacturing and/or design defect that severely compromises the safety, durability, and performance of the vehicle.
The manufacturing and design defect includes a weak or insufficient floor panel in the unibody of the vehicle that causes, among other things, cracking in the floor pan and misalignment, cracking or the complete or partial failure of the rear subframe of the vehicle.
The rear mounting points for the subframe rip out from their spots in the sheet metal because the rear differential transmits the torsional load from the engine through the subframe, then into the chassis. The constant loading and unloading weakens the insufficient sheet metal, causing it to fatigue and separate from the chassis.
This problems first occured in the E36 vehicles and a correction was made in the E46 by placing a cross member on the front two mounting points of the subframe. Although the cross member keeps the front mounting points from having problems by placing the bushing and the stud in double-sheer, thus reducing the twisting action on the sheet metal, the cross member creates an unfortunate side effect in that the load from the front of the subframe is transmitted to the left rear of the subframe, causing failures of the chassis, which then affects the safety of the vehicle.
The cross member is defective in that it experiences movement, which then causes damage to other parts of the vehicle, including the floor plan. The cracks may initially develop during the warranty period, but not become visible to the naked eye until the warranty period has already expired.