The 4 lug wheel. There are no great 4 lug wheels. Fortunately the E36 has an assortment of parts that allow you to change over to a 5 lug wheel. I'm not going to get too technical but here's what I did to change from 4 lug to 5 lug.
The rear - I used E36 95-99 318ti rear control arms. They are a direct bolt up. 318ti control arms are fairly cheap and easy to get. Make sure you get the rear calipers and rotors to go with the arms as you not only go 5 lug but get slightly bigger brakes. You should probably use 318ti axles shafts, but you will need to use E28 differential flanges to make them work. I kept my E30 axles but there are only about 2 threads showing past the axle nut. The e36 hubs are about a 1/4 inch wider. You will use your E30 E-brake cables on the new arms.
You could use Z3 control arms to change to 5 lug, but it is my understanding you need to bend the metal brake line on the control arm. The ultimate control arm is the MZ3. Then you get huge vented rear rotors. But you will need the brakes and the axles to go with these. Expect to spend a lot of $$$$ and have fun trying to find them. You can keep your E30 lowering springs or use some E36 lowering springs as they look exactly the same. The spring perch on the E36/Z3 control arms is in the same spot. The rear shock mount is also in the same spot.
Differential - While changing the control arms and axles, I changed my differential over to a LSD 3.25 from an 87 535is. My original diff was 2.93 one legger that loved to spin every time I turned the corner in the rain. Now with the S3.25 I stay in the power band running through the gears and it's a lot more fun changing lanes going through traffic. I get around 21mpg with the S3.25.
You will need to change the rear differential cover to an E30 rear cover to use the E28 differential. If you can get the Z3 M3 rear diff cover, this will also work, plus give you cooling fins. I believe it also holds an extra quart of fluid.
I chose the S3.25 differential because this is supposed to be the optimal gear ratio for a M50/S50 conversion. After doing the swap, I find that the S3.25 is the perfect gear ratio. In 5th gear at 80mph on the free way I am running close to 3,000 rpm.
The front - The front requires a little customizing, but is pretty straight forward. The parts list I used goes something like this:
96-99 M3 S52 front control arms
88-91 M3 S14 control arm bushings
95 M3 Complete front struts with kingpins (Knuckles or Spindles)
95-99 M3 Brake calipers (M logo cast into the caliper)
95-99 M3 Brake Rotors and Pads
Braided Steel Brake lines - Always nice, especially when you come across a good used set
To make the struts bolt up to the car, you will need to change the bolt pattern of the strut cap. The three studs that bolt the cap to the car are spaced differently than the E30. I punch the studs out of the cap, then marked new holes on it by putting it in place on the car. M3 strut caps have camber adjustment built into them. You need to make the strut lean as far in toward the engine as possible without the spring hitting the wheelhouse. With new holes marked and drilled I pushed the studs into the new holes and hung the struts.
You need to change the control arm bushing over to the E30 S14 m3 bushing. It has an offset center hole rather than the hole being centered. The geometry of the M3 control arm plus the offset bushing help stand the wheel back up, otherwise it leans out. That is also why you need to lean the strut as far in when re-drilling the bearing cap holes. It takes modified coil overs to get your struts to lean in any more. DO NOT use 325 struts. The spring is a much larger diameter and the strut itself will not work with a M3 strut cap. E36 M3 springs and E30 springs are the same diameter, so if you have E30 lowering springs they should work with the E36 M3 struts.
The M3 control arms bolt into place the same as the old E30 ones. You have to press of the old bushings and press on the new ones before installing. The E30 Sway bar links also bolt to the new control arms.
Brakes - My ABS was not working before I did the swap, so I did not try to make it work with the new components. I kept my stock master cylinder. With the new bigger brakes my car stops exceptionally well. Even with the stock master cylinder, my brakes lock up with no problems.
Wheels - Once converting to 5 Lug there are a lot of wheel choices. Because you used E36 parts to swap to 5 lug it is best to stick to 3 series wheels. E36 and E46 wheels are the same offset, which is similar to a front wheel drive car. The inside of the wheel is a lot deeper than say a 5, 6 or 7 series. 3 series wheels will not fit a 5,6 or 7. The inside lip hits the strut before the hub surface. If you use a 5,6 or 7 wheel with the 5 lug E36 conversion the wheel may stick out past the fender. All 5 lug BMW's use the same bolt pattern.
Originally I went with a 6 spoke E46 16" wheel because I had access to a set. Now I have a staggered set of Style 42 Light Alloy Cross Spoke II wheels from a 2000 Z3 3.0. I think they really set the car off. 7 1/2Jx17 up front and 8 1/2Jx17 in the rear with 235/45ZR17 and 245/45ZR17 tires.
