My advice is as follows:

• Find someone in your area with the suspension you are considering and get a test ride.
• Look at the numbers in the table below that correspond to your vehicle and compare the measurements with your current ride height to see if the estimated outcome will be in the vicinity of what you expect.
• Lowering an E39 or achieving a tighter and better-handling suspension almost always increases the harshness of the ride. For this reason, don't second-guess the BMW engineers that produced the stock sport suspension. It's probably the best compromise between handling, ride height clearance, comfort, etc.
• Don't always believe the aftermarket manufacturer's specs on how much their components will lower a vehicle. Many times they do not specify if that amount is from the sport or non-sport suspension. Hence the need for the table below.
• Lowering your car with plus-sized wheels/tires? Read up on Fender Rolling which includes other possible necessities to ensure sufficient wheel well clearance.
• Please do not ask me for expected drop results or ride quality questions. I've simply compiled this info and only know of the particular results of my suspension swaps on my car. Your expectations/results/satisfaction will most definitely differ based on your driving style and local road conditions. It's best to follow advice #1 above and ask helpful folks on the Internet E39 message boards for current info.

• There are some indications that different shock/strut manufacturers place their perches at different heights, thereby causing slightly higher or lower ride heights independent of what spring is used. Bilstein Sport's don't seem to lower the front 540 suspension as much as Koni's for example. One possibility is the perch heights are different. Another rumored possibility is the higher gas pressure in the Bilstein's prevent as much of a drop as the Koni's.
• M5 suspension components on non-M5 E39s doesn't seem to be a popular choice. The M5 weighs slightly more than a 540 so the best you get is sport or slightly-higher ride height. Handling will improve, but for the same cost, quality aftermarket parts could be a better and longer-lasting option.
• Koni's are generally shipped at the middle dampening setting and most folks leave it there.
• Adjustment of rear Koni shocks requires the entire shock be removed from the car, so fine-tuning dampening settings doesn't appear to be practical.
• Koni rear perches have 2 height settings and should be placed on the lower perch setting as per Koni directions.
• Generally, when using lowering components, the bump stops should be cut according to any specs listed in the shock/strut instructions.
• Replacement of the front lower spring pads is usually recommended due to it's thin profile.
• Replacement of the strut pinch bolt is highly recommended as noted by BMW and www.zeckhausen.com.
• The front struts should be rotated so that the "L" or "R" is lined up appropriately with the gap in the lower strut clamping area. This will point the perch hats slightly rearward.
• Please do not ask me for suspension installation instructions. Although I've seen people post rough outlines regarding the E39 procedure with few or no pictures, changing critical usage and safety components such as springs and shocks isn't necessarily a DIY job. Specialized knowledge and tools (i.e. spring compressor) are required for repairs such as these, so proceed at your own risk. It's highly recommended to have someone with experience on hand and able to assist you with the install or at least a good reference guide such as a Bentley repair manual handy. If you're still curious, you can view this E38 DIY write-up that I haven't inspected, but looks fairly good. Click here for an abbreviated write-up.

Suspension Survey Notes:

• H&R springs has different designations of springs for sport, non-sport, or touring (wagon) suspension, so "Sport/sport" below means "Sport model springs for OEM sport suspension cars", etc.
• A full or empty fuel tank will effect rear drop measurements.
• Listings for Touring models (wagons), generally describe only the front springs being replaced since the rear ride level can be electronically adjusted by the dealership via the MODIC.

Again, take the numbers above with a grain of salt since your results might be completely different. If you have detailed questions for a particular owner, you can try to catch them on either Bimmerfest or Roadfly. Posting your suspension-related questions and comments there is a good idea as well since it benefits the BMW community.

Questions? Comments? E-mail me:

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