This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your BMW 3 Series. The book contains 272 pages of full color projects detailing everything from performance mods to timing the camshafts. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any 3 Series owner's collection. The book was released in August 2006, and is available for ordering now. See The Official Book Website for more details.
In part two of our suspension overhaul series, we will focus on replacing the rear shocks and springs in the BMW E30.
As you can see in this first photo, this is my car prior to the installation (Figure 1). The suspension on the car had seen better days. I continually noticed that the car would pitch and roll over nearly every bump in the road, indicating that the shocks were blown.
I decided to replace the stock suspension setup with a set of Bilstein Sport Shocks (Fronts shown in Figure 2) and Eibach Performance Springs. My intention was to create a suspension that I could comfortably enjoy on the street, and still retain the option to take it out to the track if I choose to do so. Also, E30s just look killer when dropped.
The first step is to remove the bolt covers on the wheels. (Applies only to is style wheels). Use a set of channel locks to rotate the hub caps and remove them. See Figure 3 and Figure 4. While the vehicle is still on the ground, loosen up all the lug bolts (Figure 5). Youll find this difficult to do when the front wheels are up in the air, unless you have an impact wrench.
Next, you will want to jack up the rear of the car. Make sure that whenever you are working with a jack, to use caution and always remember safety first. Its a good idea to chock the front wheels from both the front and back. Keep in mind that since you will be raising the rear end off the ground, the parking brake will become useless, and there will be nothing to stop the car from rolling in the front.
With the front wheels chocked, jack the rear of the car up using the suspension crossmember. Its a good idea to place a rolled-up newspaper in between the jack and the crossmember to prevent cutting through any undercoating or damaging the underside of the car. Once you have reached a certain height, place a jackstand under the factory jacking point on either side of the car (Figure 6). Place it under the cross-member if you are using u-shaped jack stands.
Once the car has been secured on the jack stands, the first step is to undo the straps that hold the muffler to the car (Figure 7). This is performed so that we can have clearance for the trailing arms and differential to rotate downward. Simply use a good penetrant spray on the nuts before loosening them to prevent stripping the threads. Once the nuts and straps are removed, place a jackstand under the muffler to hold it in place, and prevent possible damage to your exhaust system. The next step is to remove the front exhaust mounting bracket, located just in front of the drivers side trailing arm. This bracket holds a rubber retainer that attaches to the exhaust system. Removing this will allow further clearance for the trailing arm and differential assembly.
Now that the exhaust system has been loosened, the next step is to remove the shocks themselves. The first step is to place the jack under the trailing arm; this will take the preload off of the trailing arm and prevent the arm from crashing downward when you try to remove the shock. Next, you will want to remove the 13mm nuts that hold the rear sway bar drop links to the trailing arm (Figure 8).
Once the sway bar links are disconnected, you will want to place a jack under the differential to support its weight. Disconnect the speedometer sender on the back of the differential. After you disconnect the sender, look up at the rear differential mount. It is essentially a large rubber bushing, with a bolt through it. Using an open-ended wrench on both sides, loosen and remove the bolt. This will allow the differential to drop down when you lower the jack (Figure 9). Note that Figure 9 shows the sender still installed - a small mistake that we realized when the wire became suddenly tight! Drop the differential slowly using your floor jack. This will lower the pivot point for the CV joints, and allow you to rotate the trailing arms down enough to remove the rear springs. When the differntial is being lowered, watch the brake cables to make sure that they don't hang up and catch on the rear sway bar.
Now, have a helper stand on the rear trailing arms, this will force the trailing arms down, and allow you to remove the rear springs. You should be able to simply pull them out (Figure 10).
With the rear springs out of the car, its a good time to remove the shocks from their top mounts as well. The first step in doing this is to open the rear trunk, and remove the plastic lining that runs along the inside of the trunk. There are several small tabs on the upper inside lip that simply bend down; allowing you to slowly put the liners out. Once the liners are removed, you will see the upper shock mounts. They are held in place by two 10mm nuts (Figure 11). Have a helper hold the shock from the bottom of the car and unbolt the mount. The shocks should now be free from the car. Once the shocks are free, place the shock rod in a vise and remove the self-locking nut on the top of the strut mount, this will separate the shock from the mount.
Now that the shocks are free from the mount, slip the mount over the end of the new shock and use a new self-locking nut to hold it in place. Have a helper place the new shock in the perch on the car and tighten the two 10mm nuts that hold the mount in place (Figure 12).
With the new shocks installed into their top mounts, you should install the new springs at this point. Have a helper stand on the trailing arm, and slide the new springs in place. Make sure that the upper and lower rubber spring pads are in place before doing this (Figure 13).
Once both springs are in place, you will want to place a jack under the trailing arm, and raise it until the bottom of the shock lines up with its mounting point on the trailing arm. Slide the lower shock absorber bolt through the shock and thread it into the trailing arm. This will keep the springs in place. See Figure 14 and Figure 15.
With the new shocks and springs installed, it is now time to reconnect the sway bar links, simply line them up in their respective positions on the trailing arm, and re-install the 10mm nuts that hold them to the control arm (Figure 16).
Now you will want to jack the differential back into position. Slowly start jacking up until the rubber mount lines up with the upper bracket and slide the mounting bolt through the bracket and mount. Using an open-end wrench and a ratchet, tighten the mount to the factory torque setting (Figure 17) .
Last is the exhaust system, First, re-attach the straps that hold the muffler in place. You may have to bend the straps a little to get them line up correctly, so use caution while bending them. Once you have them in place, simply tighten the 10mm nuts that hold the straps (Figure 7).
Next, re-install the front exhaust bracket. You will find it easier to install it at a slight angle, thread the 10mm bolt in, and then tighten it. As you tighten the bolt, it will bring the bracket back straight and hold the exhaust system in place.
Now you can re-install the tires on the car. Make sure the lug bolts are seated corrected and tighten tem as much as possible while the car is jacked up. Raise the rear of the car on either side and remove the jack stands, and lower the car onto the tires. Once the car is back on the ground, torque the lug bolts to keep the wheels from flying off. Now all you need to do is put the wheel covers back on and thats it, youre done!
The following pictures show the finished result, a huge improvement in the overall look of the car in my opinion. Performance wise, the car now has outstanding handling, the pitching and rolling is gone, and the car feels incredibly stable.
Figure 18: 325is lowered after installation.
Figure 19: 325is side rear view, lowered after installation.
Figure 20: 325is front close-up, lowered after installation.
If anyone has any questions regarding installation feel free to email me at The Pelican Parts Message Center
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