In the world of suspension tuning there are two important factors to consider when choosing a setup for your ride: handling and comfort. When you drop your ride, it usually lowers the center of gravity, shortening the distance the coils and shocks travel. Because of this, the damping force of the shock must be stiffened to prevent the car bottoming out on the suspension. This can improve the car's handling and decrease body roll, thus giving you a sporty experience when making those 60mph on-ramp turns.
But what's the price to pay for this excitement? You sacrifice ride comfort. It's simple - if you increase the damping force and reduce suspension travel, the ride is stiffer and you'll be able to feel every bump and dip. But why is it so hard to get both great handling and ride comfort? It's because they're at opposite ends of the spectrum and most stock suspensions try to find a happy medium. Unfortunately for us, they often err on the side of caution and make things too soft. So we can go in, stiffen it up and make great improvements.
Most aftermarket shocks are adjustable to help you tailor your setup. This allows you to choose your ride comfort to a degree, but the problem is they must be adjusted manually. Depending on the shock design, it can either be done from the top or the bottom of the damper, meaning you either have to crawl under the car or pop the hood and trunk to adjust them. Either way, you need to pull over to adjust them on the road, and that's just inconvenient.
However, there are technologies out there to help you, including the EDFC from Tein (reviewed et 1/06). The Electronic Damping Force Controller is a unit that electronically adjusts each shock from the comfort of the driver's seat. It features paired front and rear shock adjustability, three presets, 32 levels of shock tuning, a backlit LCD controller and a self-checking/warning function to alert you if something's wrong.
The EDFC uses four electric motors mounted on top of each damper. They're linked to the control unit via two harnesses: one for the front pair and another for the rear. It's a simple concept - the control unit sends electric pulses to the motors to turn the hex screws on top of each shock. It can do this in increments of 16, or more refined half turns of 32 levels, depending on which mode you choose.
Not all coilovers are compatible with the EDFC. For instance, the coilover has to be a Tein product and then only certain models can be used. The key to EDFC is the shock requires a needle valve design. With each turn of the hex screw, the needle act as a valve, and either opens or closes depending on which direction the screw's turned. When the screw is turned, the needle valve closes and becomes restrictive, allowing less oil to travel. This is how the EDFC stiffens and relaxes the ride.
The EDFC unit is purchased separately from Tein coilovers, allowing you to select the suspension of your choice and upgrade to EDFC at a later date if compatible. And to show you how easy they are to install, we went to Tein's R&D facility to oversee the installation of a Super Street coilover system and EDFC on our E46 323ci project car.
The installation of both components is pretty basic. In fact, the most time-consuming aspect of the install is threading the front EDFC wiring harness through the firewall, and disassembling the interior panels to route the rear harness. But before installing the EDFC, the suspension has to be swapped out.
Once everything is installed, reattach the battery and turn the ignition to the 'on' position. You should hear the EDFC motors making a shuffle noise. That's the self-check procedure ensuring everything's functioning correctly. It will then make an audible tone. If for any reason something's wrong, the unit will flash and will let you know which corner is affected.
Adjusting the damping force is simple. There are separate buttons to stiffen or soften the front and rear dampers. It's a great system with three presets for settings you're likely to use often - say cruise, curves and track. We recommend you take advantage of the presets as they truly give you the convenience you're seeking for everyday driving on the highway, cruising or perhaps a sporty setting for autocross. Whatever the conditions, EDFC puts adjustment of the damping force within reach of your fingertips.