There are lots of ways to arrive at a decent handling Camaro. One of the quickest and most affordable ways is to start with one that already benefits from 40-odd years of improved suspension geometry. So when Bill Irwin wanted to improve his autocross skills, he decided that starting with an ’00 Camaro would get him further, quicker than the massive improvements that a ’69 Camaro would demand. Once he was carving the corners with his fourth-gen Camaro, the next move was to upgrade the shocks and spring rates. Bill owns a small shop called Thunder Valley Hot Rod Shop in Thayer, Iowa, and in the midst of his parts search, he discovered that Viking Performance not only had what he was looking for but was just up the road in Lakeville, Minnesota. He combined these shocks with a brand-new rear conversion kit from UMI Performance that allowed him to install the rear coilovers without the need for fabrication or welding. It was literally a bolt-in affair.
The upgrade process went something like this: Viking sells only double-adjustable shocks, but their prices are still very affordable. The advantage to double-adjustable shocks is the tuning that allows separate modification of the compression adjustments from the rebound (expansion). We’ll get into these advantages in the Shock Tuning sidebar later in this story. But before Bill could tune, he needed to install these parts. So follow along as we work with Viking and UMI Performance to install coilover shocks and springs on all four corners to yank this ’00 Camaro out of its handling doldrums.
01. The buildup started with a complete set of front and rear, double-adjustable, 2 1⁄2-inch diameter coilover shocks from Viking Performance. The front kit is a direct bolt-on arrangement, but the rear required the custom mounts from UMI Performance. Bill also upgraded both front and rear coilovers with the thrust bearing kit. Viking shocks offer an adjustment range of 19 separate clicks for both compression and rebound.
02. The thrust bearing kit places these Torrington bearings between the adjusters and the bottom of the spring to allow easier changes to ride height with the spanner wrench. While this bearing makes adjusting ride height much easier, there is also evidence that it minimizes binding of the spring to the shock under compression.
03. It’s a good idea to coat the threads on the shock body with anti-seize to prevent galling, since both the adjuster and the shock body are aluminum. This will prevent seizing the adjuster to the shock body, which can ruin your whole day. Now is a good time to measure the front and rear ride height as a reference for after the coilovers are installed.
04. Bill chose Viking’s heaviest 550 lb/in spring for the front of the Camaro. This is a good starting point for a street car, but there are several very quick fourth-gen Camaros (including a very quick one owned by CP editor Nick Licata) running much higher front spring rates. While stiffer rates do affect ride quality, this can be softened by merely adjusting the compression valving, so don’t be afraid to increase the spring rate in the front.
05. Here is the left front upper mount installed on the Viking coilover. The master cylinder must be loosened enough to access the upper chock mount bolts on the driver-side, but this can be accomplished without removing the brake lines.
06. The lower mount merely bolts in place, and all that’s left to do is mount the tires and wheels and set the ride height. Remember that any ride height modification has a direct effect on the alignment, which will have to be reset.
07. The UMI upper mount offsets the rear coilover from the OE coil spring position yet still places the load in nearly the same location.
08. Accessing the upper rear mount for the coilover requires removing the back seat plastic panel on both sides to install and torque this connection.
09. This is the UMI lower rear shock mount. Note that it does not rely on a single shear location for the shock (and the load), but adds a horizontal 3⁄8-inch fastener slightly above the lower mount. Bill had previously added a rear suspension relocation mount that required a spacer for this bolt that is provided in the UMI kit.
10. This shows the location of both lower fasteners that share the load.
11. Bill used 12-inch length, 150 lb/in springs for the rear application. Here, the final ride height has been set and now he’s ready to take on those orange autocross cones.
Shock absorbers—or more accurately—shock dampers are probably the least understood component in a typical suspension. Spring rates, camber angles, and soft-compound tires are fairly easy to understand, but shocks can be a bit intimidating to rookie tuners.
Let’s see if we can shed a little light on this black art. The shock absorber’s job is to dampen the natural oscillations of a spring. We’ve all seen what happens to a car with dead shocks. The valve settings in a non-adjustable shock will always be a compromise for any vehicle. So by creating an adjustable shock, we can tune the car for varying track conditions. And we can tell you that track conditions and different courses demand plenty of tuning latitude.
A shock will dampen spring oscillation in two ways: in compression as the shock is compressed (also called bump) and in expansion, what shock engineers call rebound. Think of a shock as affecting the rate at which a spring compresses and expands as the car negotiates a turn or bump. The spring’s job is to absorb bumps and keep the body from collapsing over the tires. The shock’s job is to mediate, or affect, the rate at which the spring does its job. Let’s take a look at what happens at the front of the car when it enters a left-hand turn. The driver moves the wheel to the left, the body immediately begins to collapse the right front spring while the left front spring extends. The right front spring will eventually seek its natural position based on the load applied. With a higher-rate front spring, the right front will compress slightly while the left front will extend. The rate at which these springs move is determined by the shock valving.
So let’s say that we have our Viking shocks set according to Viking’s starting recommendations for the bump and rebound (at 10 and 8, respectively), and we’ve pushed the Camaro through several more corner entries and exits to get a feel for the handling. We’ll assume that it pushes, or understeers, on corner entry. This can be because the shock and spring package is too stiff, or it could just as easily understeer because the front suspension is too soft. For this discussion, let’s assume it is too soft, so let’s increase the compression valving from 10 to 14 clicks and re-run the autocross course. Upon return, let’s say the car responded with improved corner entry feel and pulled off a better lap time.
What this tells us is that the car is probably under-sprung in the front. Let’s say that the car responded with better lap times until we maxed out the adjustment range on the compression side of the front shocks. This tells us we need a stiffer spring in the front (or a combination of a stiffer front spring and a larger front sway bar), which will allow us to bring the shock valving back to a mid-point adjustment. This gives us room for further shock tuning without approaching the end points of the shock valving. We also would still have plenty of room to soften the valving for the ride home after the race.
We have not addressed rebound tuning or even the effect of rear suspension bump and rebound tuning on the car because of space considerations. In addition, we only addressed corner entry. Shock tuning also affects the car at the apex of the corner and especially on corner exit. So you can see that there is much more to shock tuning than just how the car rides cruising down the highway. But with the adjustment opportunities a set of double-adjustable shocks affords, you have the tools to improve handling much easier and quicker than ever before.
|Viking front coilover kit||A206-550||UMI Performance||$499.95|
|Viking thrust bearing kit||7995-102||UMI Performance||44.95|
|Viking spanner wrench||7995-101||UMI Performance||19.99|
|Viking rear coilover UMI kit||2046-150||UMI Performance||659.99|
Thunder Valley Hot Rod Shop