Despite the impression that every drag racing event is held on a racing surface that is glass-smooth and stickier than a flytrap hanging over your summer picnic table, that’s rarely the case. Whether it is a surface that has seen better days, a dragger that is sorely in need of new donor slicks, a lack of glue in the sprayer, or even a no prep-style event, racers are often forced to get down when the gettin’ ain’t so good.
In these situations, the racer must look at different vehicle components to gain an edge and safely get down the track. Each suspension element from the front to the rear of the vehicle plays a part in its performance and consistency. A conversation with QA1’s Tim Anderson walks us through the essential fundamentals a racer should consider when sorting out a vehicle for a tricky track surface.
Getting your car set up correctly is not as simple as installing suspension parts, then adjusting the dampers to work with the track surface. For a dedicated track car, it’s important to make sure the individual components and pieces are in alignment and optimized for performance.
“Bumpsteer is a critical chassis adjustment that needs to be set properly on your chassis for when you’re in any suspension movement. Having that close to zero is very important with the front-end movement that you see in a drag car, in the initial launch and then it coming back down and during the movement to get downtrack,” says Anderson.
You’re trying to have a quick weight transfer initially and then smooth it out as you launch out of the light.- Tim Anderson, QA1
“Another thing that is critical to the front-end geometry would be making sure that there’s sufficient caster to keep the wheels pointed straight with minimal wheel effort.”
Recommended settings would be in the 5-to-7 degree positive range, which will keep the car rolling easily down the track without the driver having to saw on the wheel to keep it straight. Additionally, the camber should be adjusted correctly to work with the tire on the vehicle and set the same side-to-side. Unlike in a street car, where there is often a half-degree offset to combat road crown, on the dragstrip, it’s crucial to be as flat as possible since the surface is typically flat. And it’s also important to take measurements to ensure that the rearend housing is straight in the vehicle and not driving it to one side or the other.
Outta’ The Hole
Anderson stresses that when the grip is less than optimal, the most critical thing a racer can look for is weight transfer. While this may be a bit of a compromise for the absolute lowest elapsed times, planting the tire successfully down the track will make the car much more consistent and less likely to get out of shape. To do this properly, you need at the very least a double-adjustable damper — especially for those marginal surfaces.
“You’re going to want more weight transfer to go from the front to the rear; as you do that, you run less rebound in the front. That’s going to allow the front to rise and move weight to the back. Also, at this time, you would run more compression in the front. As you get more lift, it’s going to come back down eventually, and you need to have the compression to hold that weight,” Anderson says.
If the track has more grip, it’s helpful to add more rebound in the front; this will slow down the rate of rise to help control wheelstands.
In the rear of the vehicle, it becomes trickier to nail down the settings as there are several ways to get down the track effectively. Generally, less compression with more rebound will help control the tire; as the weight transfers, the car will settle in over the rear suspension, and the stiffer rebound setting will slow the rise of the shock as the vehicle tries to absorb the hit. Then, as this setting is optimized, you can slowly add more compression to the front to help promote weight transfer.
If the car launches hard and then unloads, that’s an indication that the rebound is too soft, as the shock is allowing the tire to bounce back from the surface too quickly instead of maintaining control. Anderson stresses that the driver should also be in tune with the car; feeling what is happening at each end is a sign of an attentive driver and will help when deciding which changes will benefit most.
“On a marginal track, you need to soften the compression and the rebound. You’ll find the ratio that works well for your suspension setup, and you’ll find yourself going softer or firmer depending on the track. Typically, if there is less grip, you’d go softer, and when there is more grip, and you need to slow down the weight transfer, you’d go firmer,” he says.
Having a good starting point for both ends is critical, and this is where your shock manufacturer can help. It’s likely they’ve worked with similar vehicles and have an idea for what has been successful with a specific powertrain and chassis combination at your race weight. Once the vehicle is at the track with these baseline settings, you can observe what’s happening under particular conditions (have someone shoot a video of your launches!) and then make adjustments from there to optimize performance.
If the front end is too tight and not transferring the weight to the rear, then you’d loosen up the rebound a click or two and see what happens with the new settings. A few words of caution: make setting changes one at a time and take good notes — 60-foot numbers, front and back-splits, too — so you can make comparisons as you make changes. You’ll be able to maximize your success if you’re data logging with shock travel sensors.
“You’re trying to have a quick weight transfer initially and then smooth it out as you launch out of the light,” says Anderson.
On a marginal track, you need to soften the compression and the rebound. You’ll find the ratio that works well for your suspension setup, and you’ll find yourself going softer or firmer depending on the track.
Please keep in mind that this general guidance is designed to be used with slick tires. The objective is much different on a radial tire and requires its own article to discuss the concepts effectively.
Down The Track
When the track surface has imperfections at the 200-, 300-, 600-foot mark, these can upset the suspension and cause the handling to be dicey. The racer has the shock tuned for the best starting line performance, and if they need to be stiff for a given situation, the driver will feel these imperfections further out on the track.
“Being able to run softer valving is going to help you be more compliant with those imperfections. There is also something to be said about low-speed and high-speed valving, like what’s in our MOD Series shocks,” Anderson says.
Single, Double, Or 4-Way Adjustable?
QA1 offers three different types of shocks for drag racing usage: single-, double-, and finally, its 4-way adjustable MOD Series dampers. Each style is optimized for different situations.
The single-adjustable shock adjusts both compression and rebound (extension) simultaneously. While this type of damper is still far better than a non-adjustable unit since it gives the user some control over damping rates, it could be considered the base type for a drag racing vehicle and is more appropriate for a street vehicle. Softer settings with these would provide more weight transfer and grip, while firmer adjustments will reduce weight transfer and firm up the ride quality — and potentially reduce on-track grip.
Double-adjustable dampers have individual knobs to adjust compression and rebound independently and allow the driver to tune the damper to the track conditions more effectively.
Let’s talk about four-way adjustable shocks. These shocks — QA1’s MOD Series — have the traditional compression and rebound adjustments, which are what we’d call high-speed valving. These also offer an additional adjustment for compression and rebound to be handled on the low-speed side. The racers can maximize the starting line performance (where the wheel motion is high-speed) and still tune the vehicle down the track with the low-speed side as the tire navigates over the track surface in much smaller movements than what it sees on the starting line.
Put simply, the four-way shock adjustments control the larger damping effect on the launch with the traditional adjuster knobs, while the low-speed bleeds control the rate of damping effect.
“You can have a softer overall-valved shock with the bleed adjuster closed off and a medium-range main adjuster to get the same and probably go down the track a lot nicer. Or if you have the bleed adjuster softer, you’re going to have to dial up your main adjuster firmer, and then you’ll have your mid- and higher range a lot stiffer. That would then be a rougher ride downtrack,” Anderson explains.
Like many components on a drag racing vehicle, getting the shock settings “just right” for a given set of conditions encompasses compromise. Depending upon the style of damper — single-, double-, or four-way — it comes down to the driver tuning the damper to work best in the situations where grip is worst.
Sometimes that works out to where the shock is doing the ideal amount of work down the track, and sometimes it means there may be a little bit given up in the middle or on the top end in the hunt to optimize its performance on the starting line. Ideally, a drag racing application should have double-adjustable dampers on all four corners. If the budget exists and the competition need is there, then four-way adjustable units are the hot ticket, especially when taming unforgiving track surfaces effectively.