How I Made My BMW 330i ZHP Better With Toyota Camry Parts
Look away, purists.
Everyone’s favorite legendary BMW chassis called the E46 is starting to get quite old. Whether that is good or bad is up to your perspective and what you’re looking for, but the variety of rubber suspension bushings are getting dry, cracked, and useless at their jobs. If you know E46s, then you know the issues with rear trailing arm bushings and the trouble they can cause. What if I told you that you can solve those problems for good with parts from a Toyota Camry?
Normally, the entire rear suspension of the E46 chassis hinges around a specifically tuned rubber bushing that allows the suspension to articulate a certain amount while dampening out unwanted vibrations. That bushing is the aforementioned rear trailing arm bushing, called RTAB by E46 fanatics. BMW engineers are extremely specific about how they design the kinematics of their suspension and deploy some techniques that allow the car to work with bushing deflection rather than fight it.
In any suspension design, there is an intended kinematic alignment change, which is mathematically what the suspension will do, and deflection alignment change when the suspension has force applied to it. When bushings degrade, it causes unwanted alignment changes and makes cars drive strangely. With the E46, a degraded RTAB causes substantial tramlining and steering wandering issues.
Because of the way the E46 rear suspension is designed, the toe is adjusted by the rear trailing arm brackets that house the bushings. So when the bushings degrade, the rear toe changes drastically with relatively light loads. Most folks will say to use the stock bushings, and they’re correct. I wanted something a little more high-performance, however.
Polyurethane suspension bushings are never an option to me. The constant service requirements and extra harshness for not much gain don’t make sense to me. Although folks on the forums will argue about whether or not poly RTABs are good, I will tell you to avoid them. Instead, consider a spherical joint, also known as a ball joint.
On an E46, the stock RTABs also work as their own spring rates and the deflection of the bushing is heavily considered in the design. There is a specific amount of flex the engineers were searching for that polyurethane will not allow because of the stiffness of the material. In other words, it won’t allow the suspension to work properly. A spherical joint will eliminate that entire aspect of the suspension design and allow the trailing arms to articulate freely without binding or flex from a rubber or poly joint.
I’m not qualified in engineering, but the track-oriented people I know swear by the stock rubber or spherical ideology with their E46 M3s. The problem with a “real” spherical RTAB kit for an E46 is cost at more than $250. Stock bushings are about $30. Another problem: These bushings are a mild pain to install and are known to degrade in less than 40,000 miles. I wanted a permanent solution that didn’t wreck my pocketbook.
For once, the forums offered me a solution in the form of a $50 set of Moog Toyota Camry control arm bushings that are spherical joints sealed with a rubber boot and fit exactly into the E46 rear trailing arm. I ordered two of the Moog K200786 bushings and got some 9/16 x 3-in grade 8 hardware with matching nuts for the install, which required larger bolts.
Also, instead of shelling out the cash for the specialized rear trailing arm tool that E46 owners seem to love, I figured out that the Autozone #57023 rental ball joint press works perfectly for what I needed. My parts arrived quickly, and I could solve the weird tramlining issues of my ZHP with haste.
The job was extremely easy. I started by safely jacking up and supporting the car, removing the rear wheels, and unbolting the rear shocks. This allowed the suspension to fully droop down. After unclipping the ABS sensor lines from the trailing arm, I removed the three bolts holding the trailing arm bracket to the body and let the assembly drop down enough to where I could reach the bushing with my tool. I unbolted the bracket from the bushing and set it aside for some drilling.
I decided to get the worst part of the job done and pressed the old bushings out. My rent-a-tool did it with surprising ease, probably because I used my pneumatic impact gun. My suspicions were correct because the old bushings were trashed. I reversed the setup to then press the Camry bushing into the trailing arm. It took me a few tries to get it straight but it did press in with satisfying resistance. It fit absolutely perfectly, which bolstered my confidence in this weird forum find.
After repeating the same thing to the other side, I got a stepped drill bit and drilled out the holes for the trailing arm brackets to 9/16 of an inch or M14. I tested it with the bolts to make sure, and fitted the brackets to the new bushings with some help from a block of wood and a mallet. This was another reassuring sign that this fits snugly into the car, which is exactly what you want.
To reinstall the complete trailing arm back into the body, I used my floor jack to lift the rear suspension until I could thread the three bolts in. At the same time, I reinstalled the bolts for the dampers and tightened everything to spec.
At this point, you may want to go for a long drive to test the new dynamics of the car, but it isn’t quite ready. Those three bolts from earlier are the same bolts that alignment techs loosen to adjust toe. You will absolutely, undoubtedly need an alignment after this install. A short test drive is fine, but extended driving will cause extra tire wear and potentially dangerous handling.
After I got an alignment the next morning, I marveled at how straight the car tracked over varied surfaces and how much more responsive and positive the steering felt off-center. There was still something pretty wrong with the steering on my car, but this was a huge step in the right direction. Since then, I’ve logged 3,000 miles with no issues or strange noises. In fact, the car rides substantially better with these bushings with no noticeable increase in road noise. The sensation of the rear suspension moving freely with no bushing preload is satisfying, and it feels like the car can absorb larger bumps with more ease.
Overall, you can’t beat this for the price. Since they’re sealed, they’ll last a long time, and they are hefty pieces of hardware with substantial weight. I don’t have any doubts about durability, and they are a huge improvement for much less money than a “proper” aftermarket kit for five times the money. If you’re due for RTABs, forget about the stock stuff and keep it cheap with Camry parts.