When buying or refurbishing E30 seats there are many spots to look out for: Seat top mounting tabs: The seat top is held together to the seat bottom by way of two mounting ears, and these fatigue and break.   E30 Seat Hinge Interchangeability (2/4 Door/Comfort/Sport) and Failure Point (Broken Seat Back Mounting Bracket) Seat Frame Base: There are multiple area to look out for where the sheet metal breaks.   Rear mounting bar:   Side of the frame: Seat Base Side Bolster Bars: These are normally welded only on one side, and so welding them on both sides increases strength. Seat gas spring shocks Each front seat uses 4 seat shocks to assist lifting you and provides for seat back assist (every time you use a side lever, are you feeling any assisting force?).   Eight New E30 seat gas spring shocks (E23, E24,E28) + Tool BMW 52101965645 Seat rail mounting arms: Causes seat rocking forward and backwards. Fixing rocking issue in E30 sport seats (folding)