While I was waiting, I rebuilt the brake calipers and painted them silver. Once they finally arrived, I was set to do the conversion. I used one of the lifts at work so I wasn't stuck lying on my back in my garage like a backyard mechanic.


3.) Rear trailing arm swap

First thing to do is remove the wheel and raise the rear, if you haven't already done so. I started with the passenger side first.

The brakes have to be removed, but before you start on that use a 14mm flare wrench and break the rubber caliper brake line loose (don't remove it). It's easier to loosen the line when the caliper is on the car as opposed to it hanging free. Pop out the caliper retaining clip and remove the two 7mm allen bolts on the back of the caliper. Pry out the caliper and disconnect the sensor on the back of the dust shield, then remove the two 19mm bolts holding the caliper bracket on the car. Remove the 5mm allen bolt holding the brake rotor. Using a large hammer, hit the center of the rotor hat (but not the hub) to get the rotor off.

You can disconnect the caliper now, but be warned that it will drip fluid constantly. If you have a crimp tool, you can crimp the line then take out the caliper to prevent brake fluid from going all over the place. If you don't, get a bunch of rags. On the back of the trailing arm you will see where the rubber line from the chassis meets the metal line. Using a 14mm flare and a 11mm flare wrench, break the line loose. Again, it's your choice to disconnect it altogether now or not.




Looking at the passenger hub, on the right side behind the dust shield there is the ABS pulse sensor, held on by a 5mm allen bolt. Remove it and let the sensor hang loose from the chassis. The parking brake will have to be disassembled to get the cable out, so use a small flathead screwdriver and pry out the upper spring. The retaining anti-rattle bolts have to come out, but instead of using an allen socket I used a flathead screwdriver. Turn the hub until the hole lines up with the bolt, then insert the screwdriver, press in, and make a quarter turn. The bolts and sping should come out. Remove the lower retaining spring and take out the shoes. You should see a small metal pin holding the parking brake cable to the locking actuator. There is also another small metal pin on the locking piece; DO NOT LOSE THEM! Pry the pin out of the cable, release the actuator and pull the parking brake cable out.




Remove the 19mm bolt holding the shock to the trailing arm. If you don't want to have it jump out suddenly, place a jack under the trailing arm so there is a light load on it. Pull the spring out after the shock is out. If you have lowering springs, it should be really easy. After that, the axle has to be removed. There are 6 allen bolts on the differential side and they all have to come out. To prevent the axle from spinning when removing the bolts, you may have to put the transmission in gear, pull two bolts out, put it in neutral and spin the axle, then put it back in gear to lock and remove the next set of bolts. After the bolts are all out, bunjee the axle to prevent it from hanging; I hung it from the swaybar. On the hub, use a flathead screwdriver and pry out the metal locking ring. Throw it away and buy two new ones, part number 33-41-1-124-945, list price $0.62 each. The 32mm nut has to be removed. Since I used an impact gun, it didn't take much effort, but if doing on jackstands, the Bentley manual recommends that you put the wheel back on and lower the car before loosing the nut because of the force required to break it loose.

Once the nut is out, take a brass punch and place it against the axle. Hit it with a hammer until the axle slides out, then take out the bunjee and remove it from the car. Disconnect the swaybar link from the trailing arm. Now you should be ready to pull the trailing arm off. Disconnect the caliper and any brake lines if you haven't already done so.




Using two 19mm wrenches, remove the two bolts and nuts that hold the arm to the subframe. A ratcheting wrench would be very helpful here. One problem that you may run into is the fuel filler hose on the passenger side. It was completely in the way of one of the bolts. Unfortunately for me, I filled the car with gas the night before. In fact, I overfilled the tank so I knew that there was gas in the fill tube. Rather than pulling the hose off and dousing myself with gas, I opened the drain plug below and let some of it piss out into a clean barrel.




After you get the bolts out, loosen the filler hose clamp and take out the hose. Pull the trailing arm from the subframe; it's actually not that heavy, but be prepared to catch it if it releases suddenly. Congratulations! You are now 25% done :). Installing the M3 trailing arm for me was almost the proverbial "opposite of removal," but I had to drill larger holes for the swaybar links since Racing Dynamics used a larger diameter bolt than factory. I also moved the plastic brake line retainer clip out of the way. You'll have to use a jack to raise the trailing arm in order to reattach the shock (and maybe the axle). To install the new axle hub locking ring, use the 32mm socket and hammer it in, twisting the socket as you strike it. Install the new 33mm parking brake shoe bolt, clean off the hubs, and apply anti-squeal paste on the brakes.

The passenger side should be identical, except you don't have the fuel filler hose in the way. Don't forget to bleed your brakes when you're done. I threw on my 17x8 Racing Dynamics RGQ wheels on, pumped my gas back in (hey, when 1/4 of the tank has 100 octane gas at $4.50 a gallon, you'd pump it back in too), then drove it out of the shop.






The car looked a little funny because the front shocks were brand new and didn't settle, so it was high, while the back was low because the trunk was filled with two bottlecaps, two trailing arms, and a bunch of old parts. A few days later it evened out. Unfortunately, I didn't have the proper size parking brake bolts so I didn't bother reinstalling the shoes. This became a concern a few days later when I went to San Francisco and had to park on a very steep decline, so remember to get the right bolts before installation!

And a final note about the spare: I used a 15x7" basketweave wheel from an E34 5-series, but it caused the trunk carpet to come up an extra inch so I removed the lower sound deadening plate. I also installed the larger E34 metal tire spacer to hold it down since the E30 spacer was too small and fell right through.