If you have an 84-88 BMW E30, chances are good you have the big US-Spec aluminum bumpers, affectionately referred to as “diving boards”. Now while we would almost all like to have the later style plastic bumpers, sometimes it just isn’t possible. They are expensive, and if you have an 84-87 body, the rear bumper requires a lot of modification to fit. But there is hope! In about an hour, you can push in or “tuck” your aluminum bumpers.
The method described here was done on a 1988 E30 with the shorter-style aluminum bumpers, but it should be pretty much the same procedure on and diving board equipped car. This method will also involve removing the front bumper from the car, which makes things much easier. Most people will tell you that you can do it with them on the car but you risk spraying oil all over your car, and in order to compress the shocks, you would have to drive your car up against a wall and push them in. While you will be doing this for the rear bumper, who wants to do it twice?
A big thanks to Jordan Sarette, who did most of the work during this procedure!
After finding a dry spot with plenty of room to move around and make a mess, prepare your tools and materials. You will need:
- 10mm allen wrench (88-on shorter bumpers)
- 19mm socket (84-88 longer bumpers)
- 1 big piece of cardboard (broken down fridge or large appliance box)
- 10mm socket
- Socket wrench
- Power drill and several small size bits
- 2 small screws (1/2 to 1 inch long should do – optional)
- Bench mounted C-clamp
- 1 can of PB Blaster (available at most hardware stores)
- Clothes you don’t mind getting dirty
- Protective goggles
1.)  Get on your back under the front bumper of the car. Look straight up and there will be a hole on the underside of the metal part of the bumper about six inches in from each side. In these holes are the 2 large bolts that hold the bumper on the car. These are most likely going to be stuck on pretty well, having never been touched in 12 years. Get your can of PB Blaster, and spray them down, being sure to coat the entire head of the bolt where it meets the hole. You probably want to let this stuff sit for at least a few hours. We left it overnight.
2.)  Get your 10mm allen wrench or 19mm socket and remove the two large bolts. Make sure when you do the second one that you are not under the bumper! When the bumper is loose, pull it out just a little bit until you see the wires connecting to the turn signals. Disconnect these, and set the bumper aside. Now you can get to the shocks clearly. They are located directly below your hi-beams.
3.)  Get your 10mm socket and a socket wrench and undo the two bolts on each side of the bumper shocks. After undoing these bolts, the shocks will simply pull right out from the front valence.
4.)  Secure the shock in the C-clamp, and get your drill. You will be drilling a small hole through each of the shocks. Put your piece of cardboard down on the ground under your workbench, and cover anything you don’t want getting soaked in oil.
You will most likely need the protective goggles at this point. Most bumper shocks are filled with oil, and when you drill your holes through them, the oil will spray out quite forcefully. Luckily, my front shocks were filled with some kind of oily foam that just flew everywhere. Have extra drill bits handy, we broke a couple in the process of drilling. Keep at it, they take a little work to get through.
BE CAREFUL WHILE DRILLING THE SHOCKS. THEY ARE NOT CHEAP AND WILL COST YOU $200 EACH TO REPLACE.
5.)  After drilling the holes to release the pressure in the shocks, place the shock in the C-clamp lengthwise. Then start turning the clamp SLOWLY, to compress the shock. Oil may continue to spray out, so be careful. Continue to compress the shock until the part where the bolt goes through is all the way down against the top of the flange.
After compressing the shocks, put them back in the C-clamp widthwise and drill one hole all the way into the shock, not all the way through. Put a screw slightly bigger than the drilled hole in the hole, and tighten down. This is to keep the shock from extending back out. This is optional because it takes a fairly good amount of force to compress them, and they probably won’t come back out.
6.)  After you have compressed the shocks, get your 10mm socket and wrench and put the shocks back into the front of the car. The shock flanges have room in their spaces to move up and down about ¼ of an inch, so be sure that the shocks sit at the same height on each side or else your bumper will sit crooked. Replace the 10mm bolts and tighten them down good and hard.
7.)  Have someone hold the bumper for you while you reconnect the turn signal wires. Make sure they are seated all the way, then place the bumper back on the car, making sure that the holes on the underside of the bumper line up with the holes for the bolts on the front of the shocks. Replace the bolts and tighten them down good and hard. You are done with the front bumper!
8.)  Now on to the rear bumper. This one is very easy. Grab your drill, goggles, and cardboard. Place the cardboard on the ground under the car, get on your back under the bumper, and look straight up. You should be able to see the shocks clearly on each side. Make sure your goggles are on good and tight, and drill those suckers! Once again, BE CAREFUL!
9.)  To compress the rear bumper, bring a friend and go find yourself a big, solid brick wall, like the back of a Safeway or something. Back your car straight up to wall, and have your friend guide you to about 6 inches from the wall. Put the car in reverse, and give it a little gas. Don’t romp your car into the wall, just enough so you bump up against it. Have your friend get out of the way, because more oil is going to spray out of the shocks. Once you feel the bumper is pushed in all the way, get out and take a look to see that the rear is even on each end, and you’re done!
On September 4th, 2005 I received the following email from Curtis Rosenkranz:
I'm not sure if all the bumper pistons are the same,
but my early ('84) pistons had something much
different than a standard innert oil. It smelled like
brake fluid, AND GAVE ME A CHEMICAL BURN! I still
shudder about how (in my stupidity I was NOT wearing
safety goggles) it narrowly missed my eyes! My fingers
dried out and cracked for 2 weeks. It sprayed all over
my drill, and even though I cleaned it off throughly,
my hands still dried out and cracked when I used it
I should also note that once the fluid pressure was
released, the bumpers could be pushed in by hand and
they have not moved since.
So definitely wear some gloves along with eye protection!