Please do this at your own risk. I am not responsible if you break anything. End legal mumbo jumbo.
Okay, to begin, this was performed on a 1993 318is, two doors, E36 with a Motorsport suspension from the factory, M42, automatic tranny, black on black, build date 01/1993. Your car may differ from mine. If it does, figure it out.
This DIY was also only performed with Bilstein Sport Struts, using the springs that are in place. Other Bilstein models may be different, and if you want to change the springs, simply switch them out when you assemble the new strut and spring.
Okay, on with the DIY!!!
You are going to need spring compressors for this job. I rented mine from AutoZone for a deposit of $40. They have safety locks on them, which made me feel much better about doing this for the first time.
First off, jack up the front of the car. Put the car on jack stands. Remove the wheels. Open the hood.
In the engine bay, find the strut tower. It looks like the picture below. In the pic, the 13mm nuts are marked with red and the strut bearing/ top bolt is marked in blue.
The top bolt is covered by a cap. Remove it like so: