BMW Z3 rear subframe cracking
Why does the Z3 rear subframe crack?
Worn large rubber bushings let the subframe move, so the load goes to the rear mounting lug and the spot welds. The floor panel can come loose or the spot welds can tear. The risk depends on driving style and is higher with big engines.
How do you check the condition of the Z3 rear subframe welds?
1. Remove the boot carpet and the rear panel. 2. On the Coupe, the front panel comes off with two Phillips screws, which reveals the floor panel. 3. The spot welds are under bitumen and foam mat. Check on the left, next to the upper left corner of the battery box, where the rear mounting lug is.
How can subframe cracking be prevented?
Worn front bushings should be replaced so that the rear axle moves less. Keep the rear rubber bushing original, because a hard bushing puts more strain on the lug. Reinforcements are available for the edges of the beam; installing them requires welding and rustproofing.