Are there any specific springs for the E30 318/318is or are they geared toward E30 with a M20 motor? There is a weight difference between a 325i and 318i and I wonder if spring manufacturers take that into account since E30 318i was manufactured at the end of the production run (for the North American market).
Same thing I was wondering. And what happens if I put springs from a "heavier" 318ic/325ic convertible and unique struts/shocks from a 325ix. Will the car under or over-steer, ride soft or hard, sit high or low?
Correct me if I'm wrong with this summary: The OEM Sachs/Boge struts/shocks are unreliable under aggressive driving but technology has moved on since 1991 and Boge now makes "Turbogas" aka Sachs Advantage which can make your car feel like new, but there are also other lines of struts/shocks to look into to replace OEM like Bilstein "HD" (Heavy Duty), or if you're trying to save money Sachs Super Touring and Bilstein Touring Class which are about half the price of HD's.
If your car is lowered with shorter springs you can upgrade to Bilstein Sports or Koni Sports. Or try your luck with less expensive options, like Tokico HP's or if you are really desperate, KYB, Monroe or other generic garbage which will ride badly and not last very long. On the other hand if you have money to spare you can look into a race style adjustable coil-over suspension. Loads of companies offer coil-over kits for the E30, usually between $1,000-$3,000. Such a suspension setup can make the car handle as if on rails but it will not be comfortable on a daily basis, especially on bad roads.
