Refreshing a BMW E46 M3 for Street Performance with KW V2 Suspension

The MotoIQ garage often does a lot of high-end work with pretty much state of the art components but sometimes we also do work for customers that want high-quality stuff but are mostly going to use their cars for street use and are not serious track or autocross competitors that need a ton of adjustability.  We feel that for this sort of end-use, there are more cost-effective solutions.  In this case, we had a customer with a mostly street-driven E46 M3 that had a well-worn stock suspension that wanted a damper refresh.  We felt that his needs would be best satisfied with a set of KW Suspension Variant 2 coilovers.

The Variant 2 coilovers are the perfect setup for street use.  They have moderate spring and damping rates that are a nice step up from stock but nothing too overwhelmingly stiff.  They are also single adjustable for damping with the damper adjuster mostly affecting the low-speed rebound.  Low-speed shock movements are shock shaft velocities of zero to 2 inches per second range.  This is the velocity that affects roll, dive, and pitch and is what the driver feels the most.

The front McPherson struts use KW’s Inox stainless steel construction for a long corrosion-free life.  When combined with stainless steel reinforced spring seats, you have a shock that won’t corrode and a spring seat that won’t seize on the shock body even with salty snow-covered roads.  This allows KW to offer a lifetime warranty on their Variant line of suspension.

The rebound damping adjuster is at the top of the strut shaft.  The strut also uses a progressive microcellular urethane bump stop and a dust shield.

The spring is configured to use a coilover lower seat but the stock upper seat.  The Variant 2 is designed to use the stock upper mount for lower noise and vibrations instead of a spherical bearing-equipped camber plate.

Shorter endlinks for the anti-sway bar are provided to keep the proper sway bar geometry with a lower ride height.

11 comments

  1. is there a reason kw doesn’t provide ride height adjustment that doesn’t effect spring pre-load? Does that artificially limit height adjustment? Does that even matter? Seems like every coilover ever now uses that as a sales gimmick.

    1. Personally, I don’t like preload tuning. It doesn’t affect the spring rate, just the initial force required to move the suspension. It’s better to select the spring rate you need.

    2. coilovers that have separate shock length and spring preload adjustment will have less suspension travel properly designed coilover with only spring preload adjustment for height. some are worse than others, a lot of times application driven.

      1. that is something i had in mind when i asked the question. you could easily slam your car with a divorced adjustment and ruin whatever the shock is trying to do. good point!!

        1. the thing is, its not much better with the divorced adjustment even when its not slammed… a well designed and adjusted setup can do pretty well, but it will never have the same amount of travel as a well designed 1pc setup

  2. Another great article. Thank you!

    For those of us with a vehicle for which KW does not have an application, what other brands of coilovers are quality brands for street-driven cars? I have a 2014 Honda Accord Sport and the only coilover options that I can find for my car are from Tein, BC Racing, and KSport. Knowing that there are far too many variables to consider in this comment section, would you recommend any of these three brands for daily street use? I live north of Atlanta, Georgia, and the roads are overall in good condition (no snow heaves, etc.).

    I had Tein Type Flex on my EG hatch in 2005-2006 and liked them. I have no experience with BC Racing or KSport, but BC Racing offers the option to order any spring rate (with damping to match, apparently). Thanks in advance.

      1. Thanks, Mike. I appreciate the reply.
        No luck with Feal, but Fortune Auto has a 500 Series coilover for my car. Listed spring rates are 10kg/mm front and 6 kg/mm rear. Since the front has strut suspension and the rear is multi-link, those rates seem even more front-biased than the numbers alone would suggest. I don’t know the motion ratio of the rear suspension, but being multi-link, it is obviously less than 1:1. I’m more concerned with a well-damped suspension than with a soft ride, and Fortune Auto seems to offer superior damping. Progress offers an adjustable rear anti-roll bar for my car, so I can use it to supplement rear roll resistance if necessary.
        Since Fortune Auto offers the ability to customize spring rates, are the default rates ideal, or would a stiffer rear be preferable (ie 10/8)? Or, maybe a softer front combined with a stiffer rear (ie 8/8) which would still end up being front biased after the rear motion ratio lowers the rate at the rear wheel. Any guidance would be appreciated. Thank you.

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