It generally begins as an itch to lower your car's ride height, and often transitions into a full-blown coilover installation. We should all be familiar with the thought process—because let's face it, wheel gap is just unattractive. So after the initial revelation that you indeed want to embrace "the drop," a lot of enthusiasts at this point would settle for just lowering springs. But for many others that's not enough, because while springs will bring your car earthward and at least take care of the cosmetic side of lowering, they don't have the tuning flexibility of a legit coilover system.
Which is to say specifically lowering springs have a fixed ride height and typcally non-adjustable damping, whereas coilovers allow you to adjust ride height, and often damper settings for compession and/or rebound. Before you even think about pulling the trigger on a full-blown coilover kit, though, it's probably a good idea to make sure you do your due diligence. There are a variety of coilover kits out there. You have to make sure you find the one that suits your driving style, and it probably wouldn't hurt to go with one that comes highly reviewed. If you do decide to get a kit, the differences between stock and upgraded suspension can be like night and day.
Simply looking to improve the handling on the track and still be able to get groceries the next day? H&R Springs can take of that!
Thus was the path to lowering this BMW E46 M3, and to accomplish this we picked up an RSS Coilover Kit from H&R Springs. It took myself and a buddy of mine a whole day to install the system working on a driveway (which is to say we did not have the benefit of a lift); granted, we were filming and dawdling around at points, so realistically it shouldn't take someone more than four-ish hours to complete such a job.
The current setup on the E46 M3 is a staggered setup, and I genuinely believe that most staggered setups look better when they are raked. By "raked" I mean when the front sits lower than the rear. With that in mind, I planned on lowering the car 1.5 inches in the front and 1 inch at the rear. I didn't want the car slammed, but just enough to get rid of that dreaded wheel gap.
In addition to the H&R RSS Kit, we also wanted to install shorter anti-sway bar end links. Step 1 of the process is getting the car off the ground; when you do this, there's going to be a little rubber pad next to the oil pan. That is where the floor jack should go when raising this car and putting it on jack stands.
Step 2: Remove all the wheels
Note: At this point I started working on the front of the car since it was a bit more difficult.
Step 3: Remove the sway bar end links. I used a 17mm wrench to hold the back of the nut and 16mm socket to remove the front.
Tip: It will make your life a whole lot easier if you turn the wheel opposite to the side you are working on. For example, if you're working on the front-right side of the car, turn the steering wheel to the left.
Step 4: Remove the headlight leveling sensor in the wheel well that is held onto the chassis by two Allen bolts. You want to remove this because if you don't, you risk breaking off the hinge assembly or bending the metal rod that goes to the control arm.
Step 5: There's going to be an 18mm pinch bolt you will have to remove so you can bring the knuckle assembly down. There's a special knuckle spreading tool for this particular part that will make your life easier, so I opted to use that. You essentially place this tool where you apply the anti-seize and spread the knuckle enough so you can push it down.
Step 6: Go to the hood of the car, locate the 13mm nuts that hold the strut tower brace, and remove the three nuts on both sides. Just make sure that when you're on your last bolt that you hold the strut because it will fall down.
Step 7: Remove the strut! Take note of the orientation of the top hat. There will be a marker that states which side it belongs to on the car.
Step 8: Swap top hats. When swapping the top hats, be aware there is a left and a right for the struts. It will display which side it belongs too on the part itself. When doing this, make sure you get yourself a good pair of spring compressors and keep the spring pointed away from your body. If you don't know how to use spring compressors, Google it!
Tip: The kit itself does not come with new top hats so in this case I just used my original top hats as a temporary setup until I get some adjustable camber plates.
Step 9: Once you assemble your strut, apply the anti-seizing lube onto the knuckle spreading area where the strut sits. It just makes your life easier if you want to take it out or if you want to adjust something.
Step 10: Use the knuckle spreading tool to spread the knuckle so that you can drop the strut in place. When you're fishing in the top 13mm nuts, I recommend finger-tightening one so that you can hold the strut in place. More than likely you will need to use a floor jack to raise the knuckle back up so that you can get the strut back onto the knuckle.
If you're planning on lowering your E46, get yourself a pair of shorter sway bar end links. You do not want to use the stock ones because they will bind.
Step 11: Use the 18mm knuckle bolt and thread it onto the strut
Step 12: Install the shorter anti-sway bar end link and reinstall the disconnected pieces (strut nuts and leveling sensors).
This completes the front suspension installation. Now it's time to go to the rear!
Step 13: Go to the trunk of the car and remove the interior panels and sound deadening to gain access to the rear strut nuts.
Step 14: Remove the 18mm bolt at the bottom of the strut. Make sure you place a floor jack underneath the knuckle for support because once you remove the top strut nuts, it will drop.
Step 15: Remove the two nuts at the top and be prepared to catch the shock.
Step 15: Remove the rear spring. I used a pry bar to remove the spring. Try wiggling it up and down. Also, to make your life a little easier, make sure that your hand brake is disengaged otherwise you're going to be fighting the car.
Step 16: Transfer the top hat to the H&R coilovers. It's just a 17mm nut at the top. You will not be using the old nut. The H&R shock comes with a new nut and its own bump stop inside of the dust boot, so you will not need to transfer the OEM pieces.
Step 17: Once assembled, install the new H&R shock.
Step 18: Install the rear spring adjuster. This part comes pre-assembled already, but you're going to need a special ring plier tool that can spread the ring apart and disassemble the adjuster.
Step 19: Once the adjuster is disassembled, you have to reassemble it onto the axle by using the floor jack to raise the entire assembly up.
Step 20: Tighten the small allen adjuster to lock it in place.
Step 21: Reinstall the spring and make sure it is seated right, then you're good to go.
Tip: Pre-load everything before you tighten it otherwise the bolts may back out.
Step 22: Adjust your ride height to your preference and put on your wheels. Be sure to torque to spec!
Step 23: GET AN ALIGNMENT. I cannot stress how important it is to get an alignment once you install coilovers.
The car is sitting at 25.5 inches at the top of the rear fender arches and 25 inches at the front. Once I had the H&R coilover suspension dialed in, I went for a little fun drive. Needless to say, the performance was just as expected. The suspension kit serves its purpose, transforming the M3 into a grocery getting, track-ready car. The cornering speeds I was able to take with the upgraded suspension were well beyond expectation. It was just mind-blowing to see how much more handling was increased by a simple install. The build quality of the components is impressive, too. In my opinion, this kit strikes the perfect balance between track and street use. I couldn't be more satisfied with the setup.
I will say coilovers are not for everyone. They cater to those who want a little bit more, and have a more sophisticated peroformance vision than just a drop. Don't get us wrong; there are sacrifices that come with coilovers, primarily ride comfort and practicality, but it all boils down to what type of car enthusiast you see yourself as and how far you're willing to go to dial in that perfect ride.