Times have changed, and so have suspensions, especially on sophisticated sports cars like the Corvette. The latest C5 and C6 models employ a transverse monoleaf setup in the rear, allowing for slight adjustment. Not that there's anything wrong with it, because the factory geometry is pretty impressive right from the get-go.
Even so, Corvette owners in general have high expectations, so it's not uncommon to see them lavish all sorts of attention on their special ride.
When it comes to lowering the suspension for that hunkered-down presence, though, this procedure has the potential to reduce compression travel, leading to a harsh ride. Another potential problem results from the roll center being lowered to greater degree than the center of gravity (CG). The result is a sporty look, but impaired handling with more body roll due to increased leverage of the longer "arm" (the distance between the CG and the roll center). And if a stiffer set of swaybars is added to compensate, the problems can get even worse.
To avoid this, Motor Sport Image (MSI), working with JME (a CNC machine shop), developed a spindle upright that raises the location of the wheel bearing 1 inch. This setup allows the chassis to be lowered an inch without any degradation in ride. It also moves the CG closer to the roll center so the car corners flatter. An added bonus is these uprights retain the stock compression and extension travel of the suspension.
This type of design has been employed by professional racing teams for several years (albeit at a professional price as well, usually as much as $6,000 to $8,000, and with only a rough aluminum finish). MSI has been able to drop the price on its drop spindles to an MSRP of $5,000, and they come with a hard anodized finish to boot.
Even though raising the bearing location was the main goal of MSI's upright design, it has other advantages. The upper ball joint location can be shimmed up or down to change the camber curve rate and roll center. And the steering knuckle can be shimmed to speed up or slow down steering.
Moreover, to facilitate brake upgrades, the MSI system employs a modular caliper mount that allows a larger caliper to be bolted directly without the retrofit mount, thus reducing unsprung weight.
To keep the installation simple, the MSI uses the stock speed sensor assembly for the wheel bearing. SKF racing hubs are an option.
For all their benefits, the MSI uprights do require grinding off a casting nub on the bottom of the control arms in order to provide wheel clearance. In addition, your customer has to be willing to run 18-inch wheels. Also, for this first production run of the MSI uprights, the parking brake has to be deleted. A second version, however, said to be available later this year, should overcome this drawback.
Steve Temple is a freelance technical writer and photographer with more than 25 years' experience. He has served as director of sales and marketing for Shelby American and as online editor for major magazines such as Hot Rod, Car Craft and Rod & Custom.
