Actually, Lemforder is one of the few aftermarket suppliers that I've used and have never had any issues with. Infact, they are an OEM supplier to BMW and MBZ (probably others as well). I'm not sure if Lemforder makes flex discs but if they do, I'd be comfortable using that.
When it comes to other brands, however, I won't skimp on critical or safety-related parts.
One time, in a pinch, I used an Üro flex disc because the BMW part was going to be special order and I needed to cinch the drive train up that weekend. The disc started developing small cracks after about 15-20K and after about 50-60K had completely disintegrated- like nothing except a few nylon cords remaining. If it weren't for the fact that I used OEM BMW hardware, that could have been catastrophic. (and I'm not especially hard on my vehicles). __________________ 
1995 318ti Base - Cosmosschwarz/Sandgrau R.I.P.
1997 318ti Active - Alpinweiß III/Sandgrau
2013 328i Coupe - Le Mans Blau |