I get a lot of random questions while at the track. One I got asked the other day was a simple question but yet complicated to answer simply because there are many ways to adjust it. The question was asked “Why do you run a higher rear wing flap on your car?” which was followed up by “What does it do to the car?” So here are some basic things you can use the rear wing to adjust your cars handling. Again I do not claim to be an expert in the field of aerodynamics. IF you are feel free to comment.
On most 1/10 cars the actual rear wing “height” isn’t adjustable and if it is it’s not by much, shims basically. However the rear wing angle is often adjustable with either a pivoting rear wing mount, or angled shims. Rear wing angle alone affects the downforce being applied to the rear tires. The more “rake” the wing has, the more downforce is being applied. In other words if the wing is “up” it’s catching more airflow pushing that force down on the rear tires.
Also where the rear wing is located on the rear wing mounts themselves can affect the downforce. The further the rear wing is back on the mounts, the more force is applied due to the additional leverage. Note: if you run the rear wing back so far on the mounts that it deflects and begins to lift up, this will be counterproductive! Don’t ask, seen it.
The rear wing “gurney” or the area that is vertical with the scribed lines on the back of the wing can also affect the downforce. In my experience this is the adjustment I reach for if I’m looking for rear end stability at high speed at the end of the straight away. The taller this is the more stable the rear of the car is while coming off the straight into a turn. So what I find is that on a high speed track if the car’s rear end wants to step out a bit at high speed upon turn in off the straight, I may try to raise the gurney. In general the smaller/shorter the track the less gurney you will likely need.
I generally care a few wings with varying gurney heights already cut out and ready to go. Wings are relatively cheap and they’re quick adjustments when you need that extra something to try when the car is good on the rest of the track. Never overlook the rear wing on your cars, if you want to see how much the help take it off next time you’re at the track! LOL