If you remember way back to the beginning of the Daytona 600 project, the very first thing I did was lower the car. This was both a good thing and a bad thing. The good part was that I was able to get the car's stance really low, just how I like it. Done properly, lowering a car enhances its handling by lowering the center of gravity and reducing the tendency for body roll. Aerodynamics are also marginally improved. And did I mention how much better it looks?
The bad news came when I discovered autocross, a venue in which I quickly learned the importance of maintaining lateral traction through transitions and applying power upon corner exit. More-advanced enthusiasts know that C5s and C6s handle best with the stock springs when lowered only slightly from factory ride height. The suspension simply doesn't work as well when radically lowered, due to lessened spring tension and changes in suspension geometry. The suspension also bottoms more easily, further exacerbating traction problems. If you want to improve the car's handling and lower it to the extreme, as I did, there is really only one thing to do: install a coilovershock package.
Coilovers have long been the choice of racers of all disciplines due to their unequalled flexibility in selecting spring rates, compression and rebound damping, and, of course, ride height. The downside is cost. No coilover setup worth having is cheap, and some of the ultra-high-end offerings (the Penske and Moton systems come to mind) are downright exorbitant. Thankfully, there are a few brilliant choices priced for us mere working stiffs.
One of those choices is the LG Motorsports coilover package. LG's setup utilizes the same Bilstein shocks and Hyperco springs that company namesake and World Challenge institution Lou Gigliotti has been using successfully in his race car for years. The beauty of the LG package is that it's completely customizable for your particular application. You need not put up with excessively stiff race springs if you're more interested in longdistance comfort.
LG uses aluminum-bodied Bilstein shocks for their light weight and excellent durability. These shocks utilize a separate, nitrogen-filled chamber to prevent aeration of the shock oil. Air bubbles in the oil compromise the shock's effectiveness with each compression-and-rebound cycle.
"We have used these shocks as the core of our coilover package on the race car for years," says Gigliotti. "We have nurtured our racing contacts to be able to carry that technology into the street products we build. The valving was dialed in by me and a Bilstein shock engineer on track."
A quick inspection of the LG coilovers will show no evidence of adjustment knobs. Asked about this apparent omission, Gigliotti offers the following explanation:"Adjustable shocks work well for drag racing because you need a 90/10 shock for the front and a 50/50 for the rear to promote weight transfer. But for all other applications, you need a tuned and balanced shock-and-spring package that works in harmony.
"The knobs on the shock work well when you change your spring rate, but if your springs are already correctly matched to the shock, adjusting the shock valving will simply move the shock out of the range of the spring. In other words, the rebound of the shock is determined by the spring rate. The rebound rate is what is acting against the spring pressure. If you change the spring rate, you must change the rebound rate of the shock, because a heavier spring rate will push the shock open more quickly. Similarly, a lighter spring will not be able to overcome the rebound in the shock and will tend to 'hang' the wheel up and reduce the tire contact time.
"So the spring and shock must work together. If you just change the shock rate with a knob, without changing the springs to match the shock change, then you have just taken your shock/ spring package out of harmony, and it will not work as designed."
Another critical consideration in coilover design is shock-body length. If the shock is too long, it will bottom out when it's loaded in a corner. LG spent the time and money to have Bilstein build a custom-length body, so there's no chance of the shock bottoming under compression. "When the shock bottoms, the effective spring rate goes to infinity," says Gigliotti. "This leaves the tire as the only shock absorber in the suspension. Obviously, this is not a good thing."
GM Performance Parts has the perfect companion components for the LG coilovers: a pair of T1 sway bars. Originally developed for SCCA Touring 1 racing, these mammoth bars dramatically improve the handling of the C5 and C6 by all but eliminating body roll. GMPP says the bars have been developed and tested both on racetracks and at GM's proving grounds, and that they offer engineering expertise, validation, and durability that only GM can provide.
The combination of the LG Motorsports coilovers and the GMPP T1 sway bars improved D6C's handling to that of a purpose-built race car, without the abusive ride. Because autocross events are typically run in parking lots, the cars need to be able to contend with bumps and other surface imperfections not usually found on racetracks. With this in mind, LG spec'd a slightly softer spring than usual, giving the car more grip on less than billiard-table-smooth surfaces. It also makes D6C supremely comfortable around town and on the freeway. And the addition of LG's sway bar end links cured one of the big knocks against the T1 bars, which is noise.
While the installation of sophisticated suspension components such as these may seem daunting, the truth is that it's really quite simple. In this issue, I'll show you the basic steps required to install the parts. In an upcoming installment, we'll circle back and give you a look at the actual setup.