The BMW E36 Z3 1996-2002 (I have the 1998 1.9) are prone to having a separation of the Rear subframe from the differential causing the drivetrain to hang off the vehicle and/or rip out of the trunk's weak aluminum sheet subframe. BMW Germany has acknowledged the problem for a few individuals over the past decade and a half and kept it on the low for them to not spread it further. BMW North America fails to acknowledge the design flaw during their manufacturing process in the North American Plant during the late 90s. The Spot Welds' quality is subpar and worrisome as this catastrophic failure of the subframe to driveline structure has various ways of presenting it self which chiefly includes popped spot welds in the truck which comes hand in hand with a cracked differential ear bracket. * To simply understand why this happens: The issue is that the metal of the trunkfloor is too thin and not adequete at holding up to the forces of the differential tugging at it. There have been documented cases of similarly "repaired" Z3's that end up basically pulling out and/or deforming the entire trunkfloor panel. The metal panel the diff crossmember is structurally tied to (and the trunkfloor itself which is above it) is simply too weak for the forces being applied through it. Adding more welds simply changes where the failure occurs - from pulling out spotwelds, to deforming the trunk floor/crossmember itself if there are too many welds for them to be able to be pulled out. There are a few kits going around that other owners have addressed to their vehicles for a few thousand dollars which includes welding and a re-fabrication of the trunk floor's structure to the subframe/chasis. It has two "caps" that sit on the framerails at either side and a "crossmember" piece which is a strong piece of metal that spans between the two frame rails and sits on top of the "caps". When installed, the differential ends up tugging at the crossmember, which then distributes the forces.....

- Reseda, CA, USA

I have a 1998 Z3 M roadster and the trunk welds holding the subframe is failing. This is a commonly documented issues. BMW dealers acknowledge the issue but BMW North America will not fix it. This is a welding/manufacturing defect that can lead to the differential and suspension components in the rear to completely separate.

- Sacramento, CA, USA

At 86K miles on my 1998 BMW Z3, the thin sheet metal bracket holding the rear differential up in place welded to the chassis split in half causing the rear end to hang. This is the second time it has happened, also at 93,500 miles, just 8 months later. The clutch is still original and the car has never been abused, or raced. I always baby the car because gas is so expensive, and this seems to be a problem with alot of other Z3's that I have seen online. This is clearly a manufacturing flaw. BMW claims the car must have had some rear end impact, even though this is clearly not the case. I would like to see them replace this part with thicker, or stronger metal as it can be a very serious problem if the differential falls out at high speeds.

- Nanuet, NY, USA

I purchased a used 1998 BMW Z3 with the 1.9 liter engine on 10/14/2010 with 90564 miles. In mid November I took the car to a mechanic for a check engine light which was serviced. The mechanic informs me there is a problem with Z3's along with other model BMW's with the way the rear differential is attached. The problem seems to be flexing in the sheet metal where the differential is attached causing failure of the spot welds holding the whole assembly together. He showed me in my trunk where two of the six spot welds had broken. I have researched this on the different BMW forums and BMW is claiming this failure is due to performance modifications or cars that have been taken to a track or autocross. I do not know the previous history of my car but it appeared to have been taken care of. On 6/30/2011 I had the car in the shop again for service work and my mechanic found two more broken welds and some separation in the rear chassis. This car is pretty much un-drivable now due to this condition. I understand there is a couple of companies that make a repair kit for this that will strengthen the trunk area and prevent this from happening again.

- Victorville , CA, USA

Z3 subframe problem. Possible detachment of differential from car.

- Brewster, NY, USA