[syenisch]

I did this install over the weekend, and since there is no step-by-step guide here, I thought I'd write one up. Before completing this install, I thought it would be about as big of a job as I would take on myself, but after completing it, I really didn't think it was too bad. The key is having the right tools at your disposal. A subframe bushing tool made for our cars is absolutely essential, as well as a second jack. You do not need to remove the subframe or even touch the rear suspension! All you need to do is lower the subframe a bit, and to do that requires a few operations. It's all detailed below. Some steps reference pictures ("as indicated"); those pictures are at the bottom of this post.

I must note that all the pictures were taken after the install was complete. This explains why in some pictures, components are visible that were removed in previous steps. I am also identifying the socket sizes from memory, so if anyone finds I am wrong, please share!

Necessary Tools
2 jacks
2 jackstands
2 chocks
2 BMW jackpads or an alternative
11mm open-ended wrench
16mm socket
18mm socket
9/16” socket
3/8" ratchet
1/2" ratchet
Rear Subframe Bushing Tool or an alternative
2 vice grips, 2 hose crimpers, or an alternative

1. Get the car up on jackstands so that both rear tires off the ground. If you don’t have the special jacking pads made to fit inside the black plastic box around the jacking points, I recommend using the largest diameter socket that will fit inside the black plastic box. Turn it on its side and jack on that. If you only put stands under the rear jack points, there's nothing to keep the car from rolling forward/backward, so be sure to put something sturdy in front of the front tires. I use a couple of homemade chocks I made from blocks of wood that I jam in front of the tires. You will be working under the car at times. Safety is #1!

2. Using a 1/2" ratchet and an 18mm socket, remove the bolt indicated in yellow on each side.

3. Using a 3/8" ratchet and a 16mm socket, remove the two bolts indicated in yellow on each side. Accessibility in this area is limited, so you have to use a 3/8" ratchet with a low-profile socket. You could use a wrench, but I prefer to use a ratchet when possible. The bolt indicated in red was the one removed in Step 2.

4. Use a pair of vice grips (or a hose crimper or something similar) to stop the flow of brake fluid in the brake lines indicated in red. Then use an 11mm open-ended wrench to disconnect the rear brake lines by detaching the fittings indicated in yellow. Once you disconnect the fittings, some brake fluid will likely leak out of the hoses on both ends. One good solution is to put a Ziplock bag around it to collect any spillage. I obviously did not!

5. Use a jack to support the center of the rear subframe where indicated by the red arrow. If you have one larger floor jack and one portable jack, use the larger floor jack here.

6. Use a 1/2" ratchet and a 9/16" socket to remove the two bolts supporting the rear subframe on each side indicated in red. These bolts have a unique head, but I found that a 9/16” socket works perfectly. A metric sized socket might work even better; I just saw it was a unique head and started trying sockets one at a time. The one in the front is deep inside a “cup” and will require a lengthy extension for your ratchet.

7. There are four rear subframe bushings, two in the front and two in the rear. (From now I will just call them front and rear.) We will start by removing the bushings on the rear. On the opposite end of the subframe from where you are working, use a second jack (portable if possible) to lift up the subframe as high as possible. Then, slowly lower the center jack to bring the rear of the subframe down a bit to give you more clearance at the corner you are working. Make sure the center jack is supporting the subframe at all times though.

8. Attach the rear subframe bushing tool as indicated in the instructions. I used a threaded rod from a spring compressor I had instead of the rod in the unit because it allowed me to attach a ratchet rather than a wrench, which I thought would be easier and faster. You could accomplish the same thing by putting two nuts back to back on the bottom of the rod. When I sent the tool back to HP I included a few extra nuts so people could do this, but I have no idea if they will be sending the tool back out that way.

Note there is a flange on the bottom of the rear bushings. This indicates that the bushing should be removed out the bottom. The bushing is in a tight press-fit, and there's a lot of friction in that interface. It will take some elbow grease to get it out. For the first few turns, you are just displacing the center part vertically. Eventually the rubber will each its limit and start to bring the outside with it. Keep turning until the bushing completely pops out.

9. Next we will install the M3 bushing. Apply silicone lube to the bore in the subframe and the outer diameter of the bushing. I recommend 3 dime-sized blobs on each surface. Smear it around to evenly cover each surface. Next, attach the tool as shown. Be sure the bushing is properly aligned. It will self center to some extent, but you really don't want it entering the bore askew. With the help of the silicone lube, it should be much easier to install than it was to uninstall the stock bushings. I tried another lube and it was not nearly as easy. Silicone lube is commonly used in applications like this and really is the right stuff to get.

10. Lower the second jack on the corner of the subframe and move it to the opposite corner from the other rear bushing. Repeat Steps 8 and 9.

11. Next we will replace the front bushings on the subframe. Manipulate your jacks to give you the maximum amount of clearance on top of the bushing you are working on. The removal process really is the same as for the rear bushings. Be sure to use the tool as directed by the supplier. Again, the flange is on the bottom, so the bushing should exit to the bottom. However, when installing the front M3 bushing, the flange is on the opposite side. The M3 bushing must be installed from the top!

12. When all four bushings are installed, raise the center jack to lift the subframe up. Get it all the way up so that each corner is touching its mounting surface. Make sure the mounting pads of the subframe bushings are flush against the frame of the car. You may need work your way around the subframe with your second jack one corner at a time to get it just right. If you do, make sure not to jack it up on the bushing itself, as this could cause the front bushings to unseat since the bushing’s flange is on the top, and it would prevent you from inserting the bolt through the bushing. I recommend starting with the two rear bushings first. Once you get to the front bushing, remember that you need to pass the bolt through the deep "cup" in the arm you removed. Tighten each screw to finger tight, then come back and torque them.

I must admit I did not have torque values when I did the install. I just relied on years of experience and observation of the diameter of the bolt to torque to what I thought was reasonable. If anyone knows the torque values, please let the rest of us know.

If you have any questions, feel free to send me a message! Again, with the proper equipment, this install is totally doable. Good luck!