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One of the best things you can do to improve the performance of your car is to replace or upgrade your vehicles suspension. In this case, we will focus on replacing the front shocks and springs on my 325is. This also applies to other E30 models as well.
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 (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 find a suitable jacking point on the front of the car. In this case, the frame rail directly behind the control arm rear bushing (Figure 6). Whenever you jack up a car, always try to find a point that is part of the vehicles structure, other wise you risk putting a nice dent in your floorboards or worse. Its a good idea to use a piece of newspaper in between the jack and the frame as well, to prevent cutting through undercoating or scratching up the bottom of the car. Youll want to now jack the wheels up off the ground, enough to where you can get jackstands underneath the car. The points for the factory jack in the trunk are a good place to secure them as seen in the picture (Safety Note: ALWAYS use jack stands, trust me on this. I have a puncture scar on my right hand because I didnt use them one time, jacks DO fail. A jack stand distributes the weight evenly and prevents such injuries or worse.)
Once you have all the wheels off, thread the lug bolts back into the hub to keep from losing them, and store the tires out of the way. You will now see the front brake calipers (Figure 7). The next step is to remove the upper part of the caliper and mount it out of the way. This is done by rotating the steering wheel so that you have access to the two 13mm bolts on the upper and lower sides of the caliper. You will need to use a 15mm open-end wrench to hold the locknut on the inside of these bolts. Now remove the bolts (Figure 8). You will now be able to slide the caliper back and off its mounting bracket. On the drivers side, you will also have to unplug the brake wear indicator sensor (Figure 9). It simply unplugs. Once you have the calipers free of the bracket, use a zip tie to secure it out of the way and avoid having it hang by the brake line.
Once the brake calipers are secured out of the way, the next step is to remove the tie rods. In order to do this, you will need to loosen and remove the 19mm self-locking nut at the top, then using a tie rod puller, or pickle fork remove the tie rod from the control arm hub (Figure 10). Place the pickle fork between the tie rod and the arm, and tap it with a large hammer. You may need to give the pickle fork a few whacks with a hammer to seat it in between the tie rod and the control arm hub, but after you get it in there deep enough, simply pushing down with force on the arm should separate the tapered end of the tie rod out of the control arm hub (Figure 11). Now you will be able to rotate the strut and it will ease removal (Figure 12).
The next step is to remove the front sway bar drop link from the control arm. This will allow you to lower the control arm all the way to its lowest position once you remove the mounting bolts at the top. To remove the bolt, simply look under the control arm and remove the 19mm nut that holds the drop link to the control arm (Figure 13). The overall goal is to allow the strut to rotate far enough outward to replace the shocks.
Now we move onto compressing the front springs. It is crucial that you compress the springs as much as possible while the springs are still in the car, to take the spring tension off the top strut mount. Be prepared to spend quite a bit of time compressing the springs. It is a slow-going job. I highly recommend wearing goggles while doing this. Remember that these springs are under extreme tension. Tighten each compressor in even turns on each side to prevent the compressors from slipping off and potentially caus major injury. Just think of the force felt in the car when you go over a bump at high speed, that same kinetic energy will be directed in your general direction if a compressor slips (Figure 14).
Once you have the springs compressed fully, the next step is to remove the three nuts that hold the top strut mount to the chassis, and lower the strut (Figure 15). Its a good idea to have someone hold the strut assembly from below as you lower it down. Once you have it lowered down, you will want to remove the 19mm nut that holds the strut rod in the mount. In this case an impact wrench is handy to quickly pop the nut free (Figure 16). If you don't have an impact wrench, you will have to hold the center of the shock in place with a set of channel locks, or a special shock-holding tool.
Once you have the nut off, the control arm should be lowered as far as it will drop, this will allow you enough clearance to remove the rest of the assembly. Next, reach up inside the spring perch and remove the top strut mount; you may need to move the strut assembly to one side to gain access to this mount. Once you have it removed, also remove the upper spring retainer plate and rubber gasket (Figure 17).
Now you are ready to actually remove the old strut. Simply remove the old dust cover around the strut rod, and you will see a threaded collar that holds the strut inside the strut housing. Spray a little WD-40 around the threads before removing it to prevent stripping out the inside of the housing. There is a special tool for removing this collar, however I believe it is much easier to use either a plumbers wrench or a large pair of channel locks to loosen and remove the collar. Once the collar is removed, simply pull up on the strut; it should lift up and out of the housing. Have an assistant pull it up through the strut perch and out through the top. Be aware that there will most likely be oil on the strut itself, so have an oil pan ready.
Once the strut is removed, you should be able to simply pull the old spring off the top of the housing. Now the housing will rotate towards you (Figure 18). Look down the inside of the strut, there should be oil inside there. This usually does not indicate that the struts are leaking, as the oil is there to act as both a lubricant and a cushion for the strut. If you are using hydraulic struts, you will need to drain out all the old oil using a siphon, and refill the housing with about 1/4 quart of new oil. Regular motor oil is recommended for this. If you are using gas pressure struts, such as the Bilstein Sports Shocks we are using, then DO NOT re-fill the housing with oil, as you can damage the shocks.
In this case, I decided to switch the springs at the same time from the stock BMW units, to Eibach Performance Springs. These lowering springs drop the car approx. 1.8 inches in the front and 1.5 inches in the rear. They also improve the handling characteristics of the car greatly. If you are re-using your old springs, simply put them back in position on top of the strut housings, making sure that the spring seats correctly on the rubber spacer.
If you are using new springs, remove the compressors very slowly, once again using caution to remove tension equally on both sides, then install the compressors on the new spring and tighten the compressors til the new spring reaches full compression (Figure 19). A wrench with a built-in racheting function (like the GearWrenches) is very useful at this point.
Now the new or old spring should be placed on top of the strut housing, and rotate the whole unit back into position under the strut perch (Figure 20).
Now, with the unit lined up under the perch, simply slide the new shock down through the top of the car, through the perch, and down into the strut housing. You may need a helper to do this (Figure 21). Once the new shock is in place, slide the new threaded collar over the shock rod and thread it onto the strut housing and tighten it using either a plumbers wrench or a pair of large channel locks. Once the collar is tight, lower the protective boot (light blue, as shown in photo), through the top of the car, over the shock and slide it over the shock rod. This will protect the shock insert from dirt and grime, potentially causing the shock to fail (Figure 22). If you are installing standard shocks, the dust boot, and rubber bottom-out collar are integrated together. The Bilstein Sport Shocks have this rubber stop built-in to the shock.
Once the protective boot is in place, place the upper spring retainer plate on top of the spring making sure the rubber gasket is in place, and the spring is seated correctly on the plate. Move the whole assembly to one side and slide the strut mount up into the spring perch and carefully place it over the strut rod. Next, you will want to thread the new 19mm self-locking nut on the top of the strut rod, and hit it with an impact wrench to tighten it (Figure 23).
Once the shock rod nut is tight, have an assistant raise the strut assembly up into the spring perch; youll see that the upper strut mount is indexed to fit only a certain way into the chassis. Simply rotate the upper mount til it lines up, and then carefully move the strut assembly up into the perch till the studs protrude out the top. Simply re-attach the three nuts that hold it place and tighten them up real well (Figure 24).
Now that we have the strut assembly secure in the perch we can remove the spring compressors. Yet again, use caution while doing this, remembering to loosen using equal turns on either side. Once the compressors are removed, the strut assembly should look similar to Figure 25.
The next step is to reattach the sway bar drop links. Simply line up the thread on the bottom of the link and place it through the hole on the control arm. Install the 19mm nut on the bottom and tighten it (Figure 26). Using an impact wrench is best here, as you don't need to hold the shock steady.
You now will need to re-attach the tie rods, rotate the strut for access, the line up the tie rod and push the tapered stud through the control arm hub. You will need to place a jack under the tie rod to hold it in place and prevent the threaded portion from rotating as you install the 19mm self-locking nut. Its also a good idea to use new self-locking nuts when you do this to prevent them from loosening up (Figure 27).
Once these steps are complete, you will now need to re-attach the brake caliper. Simply place the brake pads on the caliper mounting plate on either side of the brake rotor, and then slide the caliper over the pads, making sure the pads are seated correctly. Once the caliper is installed, line up the mounting holes, then re-install the two 13mm nuts, and using a 15mm open-end wrench, hold the lock nuts as you tighten the mounting bolts. Be sure to also reconnect the brake pad wear indicator on the drivers side.
The final result should look like Figure 28.
The last step is to simply re-attach the wheel, and then torque the lug bolts to the factory recommended setting. After the tires are installed, the next step is to take the car to an alignment shop to have toe-in re-adjusted for the new suspension geometry. Failure to do this will result in increased wear on your tires.
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 29: 325is lowered after installation.
Figure 30: 325is side rear view, lowered after installation.
Figure 31: 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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