BADEN'S BMW DIY #7 – E46 Shock and Strut Replacement
Repair Job Summary
3 (out of 5)
Time to Complete (estimate)
IMPORTANT SAFETY INFORMATION
Working on and under your car has inherent dangers. If you perform the work described here, be prepared to deal with problems which may arise that are not documented in these steps. Some of these problems may require tools which are not listed here or be beyond your skill level and almost always take longer to resolve than expected. Plan for the possibility that you car may need additional time to restore to working condition. Caution must be taken to properly secure your car when working underneath it to avoid injury (or death).
WORKING ON YOU CAR'S SUSPENSION IS PARTICULARLY IMPORTANT AS IT CAN ADVERSELY AFFECT THE SAFE OPERATION OF YOUR CAR IF DONE IMPROPERLY.
Before starting, you will need to assemble some tools and supplies:
A. Bilstein HD struts (with new upper strut lock nuts)
B. Upper strut bearings (optional depending on your car's mileage)
C. Upper and lower rubber spring pads (optional depending on your car's mileage)
D. Bilstein HD rear shocks (with new upper lock nuts and washers for lower bolt)
E. Shock mounts
F. Rear shock mount reinforcement plates
G. Rear shock gaskets
- New lock nuts for (E) shock mounts. 4 in total – M8 metric size locking nuts available from Home Depot.
- Floor jack and two jack stands (having a second floor jack is often very helpful)
- Wheel chocks
- Socket set (metric, ½”) with at least 13mm, 16mm, 18mm, 21mm and 22mm sockets
- Wrench set (metric) with at least a 17mm wrench
- 6mm hex socket
- Torque wrenches (½” size, small and large size to span 24 to 110 Nm)
- Vise grip
- Spring compressors
- Dead blow or rubber mallet
- Impact wrench (highly recommended) or long breaker bar (at least 24”)
- Brake cleaner + clean rags
NOTE: While it is technically possible to install both the front struts and rear shocks by yourself, I have found that having a second pair of hands to be really helpful.
Section 1: Rear Shock Installation
The rear shocks in a E46 coupe are installed with one bolt at the bottom underneath the car and with two bolts at the top. The upper shock mounts are located inside the trunk so the carpeting and some of the trim pieces will need to be removed to be able to access the shock mounts. I have found that the lower shock bolts can be easily removed without needing to jack up the car but one the lower bolt is removed and the shock extends it may not be possible to remove it from under the car unless you jack up that side a few inches.
- Place wheel chocks on the front tires to prevent it from rolling.
- Release the hand brake.
- Remove the carpet and trim pieces in the trunk enough to expose the left and right upper shock mounts.
- Using a 13mm socket, remove the two nuts on each side of the shock mount.
- Using an 18mm socket, remove the lower shock mounting bolt. Depending on the age of your car, removing this lower mounting bolt may require a breaker bar or (preferably) an impact wrench if you have one. When you remove the lower mounting bolt, the shock will drop to the ground.
- Try and manoeuvrer the shock out from under the car. Due to the length of the shock, this this may not be possible until that side of the car is raised a few inches which may provide the clearance needed to remove the shock.
- Ensure that the original paper gasket is intact on the top of the old shock mount. If it's not, part or all of it may be stuck to the bottom of the shock mount opening into your trunk. Ensure that all of the original shock mount gasket has been removed before proceeding.
- Repeat on the other side to remove the old shock.
- The new Bilstein HD shocks will need to have some parts scavenged from the existing shocks so you will need to remove the 16mm top nut on the old shocks to remove these parts.
- You will need to remove four pieces from the old shocks: the bump stop and 3 metal washers.
- Using one of the new upper shock mounts and a new gasket, assemble the parts onto the metal shaft of the new Bilstein shock as follows:
- Tighten the nut on the top of the Bilstein shock to 27 Nm.
- Place the strut mount reinforcement plate over the shock mounts.
- Working from the bottom of the car but looking at the exposed shock mount opening at the top of the rear tire, guide the assembled Bilstein shock into place. Hand tighten the two 13mm nuts. Remember to only use new lock nuts.
- Lower the car to the ground before proceeding.
- Add the supplied washer to the lower shock mount bolt.
- As necessary, raise the bottom of the shock by hand or with a jack to align the lower shock mount bolt to the mounting bracket then hand thread the bolt as far as it will go.
- Tighten the lower shock mount bolts to 100 Nm.
- Tighten the two 13mm upper strut mount nuts to 27 Nm.
- Repeat on the other side of the car.
Section 2: Front Strut Installation
Removing and installing the front struts is considerably more work than working on the rear shocks. Not only is the removal and installation procedure more complicated but the front struts involve springs which must be removed from the original struts to be moved over the the new ones. This requires the use of a spring compressor and adds time and unique risks to the overall job.
- Place wheel chocks on the rear tires to prevent it from rolling.
- Loosen the bolts on both of the front wheels.
- Jack up the front of the car and place both sides of the car securely on jack stands. The car should be high enough so that you should have enough room to crawl under the front of the car easily.
- Remove the front wheels from both sides.
- Start on the passenger side, remove the 13mm nut from the bottom of the control arm to release the Xenon levelling switch. To fully release it from the control arm, it may need to be gently struck with a small hammer.
- Disconnect the top of the sway bar link from the strut. This requires a 17mm wrench and a 16mm socket to be used at the same time. Rotate the sway bar link out of the way.
- Remove the brake line and ABS sensor line from the clamp on the side of the strut. They are just held in place with a rubber grommet so the can both be released fairly easily by pushing on both sides of the hose at the bracket. On the driver's side, there will also be the brake sensor cable as well.
- Remove two of the three 13mm nuts at the top of the strut tower. Loosen the third nut about half way.
- Place a jack under the bottom of the ball joint. This will support the hub assembly when it is released from the bottom of the strut.
- The bottom of the strut is held in place with a single 18mm bolt at the lower clamp. Remove this bolt. Removing this bolt may take some effort and you may need to employ a breaker bar or an impact wrench if you have one.
- Have a large paint can ready covered with a cloth. This can be placed under the hub to support it on the outer side when the strut is removed.
- Pushing down on the rotor or hub, attempt to disengage the strut from the strut clamp lowing the jack as necessary. I found that using a rubber dead blow hammer was useful in separating the strut from the clamp.
- If the strut doesn't want to release, try using some penetrating oil like WD40 and let it sit for a few minutes. Rotating the strut assembly by hand at the springs to ensure that it is loosed properly.
Note: Make sure that you avoid getting any lubricant onto your brake rotor or pads. Also, you may wish to employ the use of a strut clamp spreader tool to assist with the task of removing the strut from the clamp.
- After the strut has been removed from the lower clamp, remove the final 13mm bolt at the top and remove the strut/spring assembly.
- Remove any penetrating oil from the bottom of the strut clamp and the surrounding area using a clean rag.
- Remove the upper plastic cap from the strut.
- Using spring compressors, compress the spring until the spring moves freely from the upper plate.
Note: The springs are held in place with a lot of force and extreme caution must be taken when removing the strut springs.
- The top of the stock strut has a 21mm bolt that holds everything together. Remove this bolt. I have found that having an impact wrench makes this step extremely easy. If you don't have an impact wrench, you will have to use a 21mm socket held in place by a vise grip and a 6mm hex socket or hex key. Using this method, the 21mm socket will remain stationary and the hex socket will rotate in a clockwise manner to loosen the bolt.
- After the top strut bolt has been removed, the entire strut assembly can be taken apart. Recover the the following parts from the original strut: spring, 2 washers, upper and lower spring plate, upper and lower rubber spring pads (if re-using), upper strut bearing plate (if re-using).
- Choose the correct left or right Bilstein strut assembly depending on which side you are working on. Compare the orientation of the sway bar mounting bracket to determine which one is left or right.
- Assemble the parts onto your new Bilstein strut assembly as follows:
- The Bilstein strut will come with a new 22mm self-locking top bolt. Attach this to the top of the strut and hand tighten with a socket wrench.
- Start releasing the spring compressor and ensure that the spring properly seats into the rubber spring pads and that the rubber spring pads are properly seated into the strut assembly. If the parts do not line up properly, you will need to compress the springs again and adjust.
- Tighten the top strut bolt to 63 Nm.
- The Bilstein strut will now be reinstalled back into the car. To do this, attach the strut onto the strut tower with one or two bolts tightened by hand. Ensure that the alignment pin from the upper strut bearing plate is correctly aligned with the hole in the strut tower.
- Manoeuvrer the bottom of the strut into the lower clamp and if necessary, jack up the bottom of the hub assembly until the strut is fully seated into the clamp.
- Add loc-tite (or similar material) to the clamp bolt and hand thread it into the clamp.
- Rotate the strut to ensure that the Left/Right indicator on the strut shaft is lined up with the slot on the clamp. Once the strut is aligned properly to the Left or Right marker (depending on which side of the car you're working on), start to tighten the clamp bolt – ensuring that the bracket for the hoses is not touching the strut body.
- Tighten the clamp bolt to 80 Nm.
- Hand tighten all three of the upper strut mounting bolts.
- Replace the hoses to the hose clamp.
- Replace the sway bar link and tighten to 65 Nm.
- Replace the bolt to the Xenon sensor at the bottom of the control arm.
- If the brake rotor has been touched in any way, clean the rotor with brake cleaner and a clean cloth.
- Remove any supports like the jack or paint can out from the hub assembly.
- Reinstall the wheel and tighten the wheel bolts to 110 Nm.
- Repeat the removal / installation process on the other side of the car.
- Remove the jack stands from the car and lower the car. Remove the wheel chocks.
- Tighten the three 13mm upper strut tower bolts to 24 Nm on each side of the car. This step should be done when the weight of the car is on the suspension.
- Road test the car to ensure that there are not any unusual new noises. Try to drive over some speed bumps or railway tracks as sometimes unusual suspension noises may not be heard on smooth roads.
- Clean up your tools.
- Your car will be needing a 4 wheel alignment. I have found that I like to drive the car for a week or so before getting an alignment to ensure that everything has “settled in” properly.
Section 3: Commentary
The installation job that I've documented here was done on my friend Al's E46 328 last weekend. About a month ago I also did a similar Bilstein HD strut/shock upgrade on my wife's E36 328 Cabrio. Doing two similar installations fairly close together allowed us to learn a lot about what would make the 2nd installation faster. The E36 front struts were considerably more difficult to remove as there are three bolts that need to be removed on both sides and they are all stuck on with a lock-tite material that took several additional hours to remove. It was after we did this work that I decided to purchase an impact wrench (bought an electric impact wrench from Canadian Tire). Having the impact wrench made removing all of the hardware on Al's E46 much easier. I'm just surprised that it took me so long to get one. Of course you have to also get a bunch of impact sockets as you can't use the chrome sockets on an impact wrench.
When we were planning out the work on Al's 328, we decided to replace the front rubber spring pads and the upper strut bearing. Al had mentioned that there was some weird noises coming from the front suspension when steering so we decided to add these parts. Realistically it may not be practical to disassemble your suspension and then decide if you want to replace these parts unless you can afford to keep your car in the garage for a few days (assuming that your BMW parts supplier isn't accessible on the day that you do the work).
Comments from my friend Al:
Background: Al wanted to add some comments to this page based on his perspective. Al's owned his E46 328 coupe for several years but traditionally has relied on a local garage who specialize in BMW (Nixon Automotive) for all of his repairs and upgrades. When Al and I were planning out the purchase of the Bilstein HD struts and shocks for his E46 and my wife's E36, Al expressed a lot of interest in doing both installations together. Since he really hadn't done a lot of work on his car it was the starting point for him to get a sense of how much work he would eventually want to do maintaining his car.
Al's situation is pretty common with most people who are interested in doing more and more advanced work on their car. He has the desire to do more work but is limited by the tools that he owns and his own limited hand-on experience. If he continues down the do-it-yourself road, Al will likely end up owning several hundreds (if not thousands) of dollars in tools that most of us own to be able to do more of these types of upgrades.
The main decision that always has to be faced at this point is if the investment in more and more expensive tools makes sense based on the likelihood of them being used to offset future repair costs. As always, the issue of availability of time and more importantly the desire to want to do the work has to be assessed.
- The Bentley manual (Baden: which Al bought for his car about two weeks before we did the Bilstein installation on his car) assumes that you have a reasonable level of familiarity with working on cars. Most of the steps leave out a lot of detail that you have to fill in the blanks with your past experience. I don't think a beginner like myself could buy the manual and tools and begin working on the car. If I did not have Baden's assistance the project would have been a disaster.
- If you want to take on projects like this you have to commit to the long term and many projects for the investment in the tools needed for this kind of upgrade to make financially sense (Baden: I should mention that Al’s an accountant ). The investment in tools is significant and if you only do one job and then take your car to the dealer for everything else you won't really save any money after you factor in tools, manuals, etc….
- With the new Bilsteins installed, the car feels more comfortable as the stock shocks were not working anywhere near where they should be. I'm not crashing over bumps anymore and I'm no longer getting unwanted steering changes after I hit a bump.
- I have not had an opportunity to really push the car but I expect it will handle better at the limit. Just driving around town you can't tell any performance benefit other than the comfort is greater. Having said that I expect my autocross times should improve.
- Many thanks to Nixon Automotive who provided some consultation over the phone for free (I take my car there a fair bit) and who even checked over the work we did to ensure it was done properly. I also took the car to them about 5 days after we did the Bilstein upgrade and they did the four wheel alignment.
- I'm satisfied enough that I'm willing to try a brake job next, which I think should be easier and I'm looking forward to doing the shocks and struts on Baden’s M Roadster. I think that will be a gratifying job given our experience with the other cars.
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