Now that I had wheels & tires on the car, it was time for every car guy's favorite purchase - coilovers! Setting up the stance of your car for the first time is an exciting moment. It's so key to executing your vision, and it takes the performance of the car to a new level. However, there's a bunch of supporting mods and components in the cars suspension that can also bring huge performance gains.
Here's what I've learned and applied from the E34 & greater BMW community in my build. First off I went with Broadway Static coilovers, I liked that they were hand built in the USA and were also BMW people. They offered good communication for any future needs. At my mechanic's suggestion we went with softer than standard 10k/9k springs, and upgrade to the Swift option.
Note: coilovers on the E34 have to be welded to the steering knuckle. Make sure the welds are solid before you try and do a donut in the desert have to get a tow out because your coilover snapped off.
I had no problem driving the car slammed except in a couple spots. Just enough that we raised it about 20mm from the initial position. It's still slammed but doesn't scrape or rub. It handles the track and being weighed down on a roadtrip just as well. Here's a photo of it just after the install next to my friend's stock 540i/6 for comparison.
My car already had Nurburgring pack sway bars from the previous owner which was a nice bonus. We went to poly rear subframe bushings to improve the feel of the rear end. In the front we added a X-Brace which stiffened the subframe, it also becomes the lowest part in the undercarriage which sort of protects the rest of the components in the now lower car. We then converted to spherical ball bearings in the upper and lower control arms. These are made by Moosehead Engineering and available from Angry Ass. These bearings are stiffer and have less deflection than the stock rubber bushings, therefore offering more direct feeling in the handling. I believe the lower arms are from the E32. Lastly, AKG bump steer correction plates were added to correct the suspension geometry in the front after the drop in ride height.
You can see the X Brace here along with the Revshift poly motor mounts. With hard driving this car would rip right through stock mounts. It even turned out it would rip through 80a poly and we ended up with 95a street / track poly mounts.
Another crucial E32 part for a V8 E34 build is finding an E32 750il large case diff. The diff is in a slightly shorter than stock ratio of 3.15 which improves acceleration with plenty of room up top in the perfectly geared 6sp. Of course it also makes for improved traction out of corners, better feeling on oversteer, and greater control of the car.
Around the same time I made two small tactile improvements. I ordered a custom M-Tech II wheel from AZAAutowheel, and a tall Condor shift knob. The M Tech II was a huge improvement over the (imo ugly) E36 M3 steering wheel that came on the car. I really liked how the extra leverage on the tall shift knob balanced out the notchiness of the UUC short shifter, and the closer reach became very natural over time. It was just the right setup and I haven't felt the need to go chassis mount. It just works and it's super engaging.
With these mods the car's handling is seriously impressive on track and it still exceeds my limits as a driver while punching well above its weight class. We still have a lot of improvement we can make by adding Broadway's camber plates for more front adjustment, getting a new alignment, and corner balancing the car. All of these hopefully in the near future. Next time I'll be discussing the Dinan supercharger setup on the M60B40!
