early body style Plastic Bumper Retrofit
Before you foolishly start on this project, I want you to all know how involving and skillful a conversion this is. It requires in depth fabrication, modification, material forming and some electrical work. This is not something most people can, or should attempt. If you are not sure that you possess the skills to properly pull the conversion off, then leave it to the professionals. No one likes halfass fitted body parts.
First things first. You will have to remove the stock aluminum bumpers on your e30. Along with them the rubber shrouds, bumper shocks, and front nose panel/valance. the front bumper is easiest, there are 2 bolts on each frame rail that secure the bumper shock to the frame, they should be 13mm. Remove them on both sides, and pull the bumper off the car. Disconnect the side marker and turn signal connectors at this time. The front shrouds are all held on by many 8mm screws, locate and remove them all. Now is a good time to remove your headlight and kidney grills. The front valance is held on with a assortment of fasteners, most of which 8mm screws, locate and remove.
Good the front bumper related parts are off the car, move to the rear.
The rear bumper is a bit harder. each shock is mounted to the frame rail with 2 13mm bolts. 3 of which are accessed from under the car, and the final one from in the trunk. In addition to these there are also 1 more 13mm bolt per shock, about 8-10inches down the frame rail. The passenger side bolt is easy to reach, but the drivers side one is up and under the muffler. you *can* reach it without removing the muffler, just be persistent. After all 6 bolts are removed, pull the bumper off the car. Remove all the rubber shrouds at this time, they are held on by a assortment of fasteners, most of which 8mm screws, locate and remove.
Tuck any dangling turn signal or side marker wiring into the holes they come from, you will want those out of the way. All of which you have removed so far is now basically useless, although i would save the bolts etc just in case. It never hurts to have a box of spare hardware.
Now comes the first step of the reconstruction. Take your 88+ front valance and fit it to the front of your e30. This panel is a direct bolt on part, no modification is needed to the valance. However you will need to remove both tow loops on the front of your car. Use a hacksaw, or a cutoff wheel. Whatever works best for you.
Use the hardware you removed to fit this back onto the car. Bolt the front bumper brackets to the side of the valance/fender. It should be fairly simple to figure out where and how given their shape. They mount with 2 10mm screws, with large washers. These brackets securely hold the bumper to the side of the car when you slide it on.
Grab both front bumper shocks (the plastic bumper ones) and bolt them on. Each use 2 13mm bolts. The shock with the threaded hole (for the tow loop) goes on the passenger side of the car.
Ease the bumper onto the bumper shocks, and into the side brackets, slide it in until it is flush. To reduce the gaps at the top, or to even them out you will need to adjust the height of the side brackets, and the shocks. To adjust the side brackets just slightly loosen the mounting screws, with the bumper mounted, then move it as needed, and retighten. Adjust the shocks as needed in the same manner.
Once proper gap alignment is achieved you can wire up the turn signals. Splice the old wires from your harness into the new wiring you got from a donor car. The wire colors *should* be the same so just match them up and crimp them. Wrap this connection on heat shrink tube, or electrical tape for safe keeping. If by chance the wires are different colors, determine which is the turn signal and which is the parking lamp by turning the car on, and signaling in that direction.
If your parking lights, and turn signals now function properly you may tuck the wires back, and bolt up the bumper. Bolt the bumper in place using the 2 10mm allen head bolts. Push the bolts into the hole under the bumper, and wiggle it until it goes all the way up and in. then tighten it.