b'TECH TIP PAGETech Tip 61 - Continued:The good, bad & ugly with aero.The ugly:Aero is dependent on the car going forward, making smooth, gentle changes.If you get the car in a state of yaw, the downforce disappears.The more downforce you haveor had I should saythe more dramatic the result is with this loss of downforce at speed.This is especially dangerous if you run a smooth belly pan & diffuser.When that airflow is no longer going the length of the car, that downforce evaporates instantly.Can you say oh hell?Sure you can.LOLThe old phrase live by the sword, die by the sword is very applicable here.If you have a boatload of aero downforcesay 50% or more of your cars weightand it disappears when you have the car in a 10+state of yawits going to be a 90-180 state of yaw until you hit something. If youre racing to win, you absolutely need to master smoothness, car control & know the limits of grip, to make aero your friend. On the other hand, if youre racing for fun, and to beat your friends, you may ask yourself how aero dependent do I want to make my race car? In most classes of vintage racing, full belly pans & diffusers are not legal. Thank goodness.Tech Tip 62: Grip is violent. Ever watch the tires when a nitro dragster launches? Higherlevels of grip that create higher g forcesis a higher level of violence. Ron calls this mean, a term taken from his friend Mike Naake. The meaner we make the car, the higher the level of grip & g-forces capable.This gripand violencecreates harmonics. Period. Anytime we create more grip in a race car, we will have more harmonics. Higher spring rates?More harmonics. Higher sway bar rates?More harmonics. Stiffer valving to control the springs & bars? More harmonics. Shorter sidewall tires? More harmonics. Wider wheels & more tire pressure? More harmonics. Big aero creating downforce and load on those springs & tires? More harmonicsand violence. Ok. Ok. There are exceptions to the rule. Eliminating chassis bind reduces harmonics. So does eliminating stiction throughout the suspension.But, for the most part, creating a race car with a high level of grip, brings a high level of harmonics with it.This is not comfortable in the car. In fact, it is downright uncomfortable & will wear out the average driver in a shorter time. If the goal is to build a winning race car, the driver & crew need to embrace harmonics as a side effect of going faster.The driver needs to be in better shape & not complain about the harmonics to the crew. Because the only cure is to reduce grip & slow the car down.Now, if you racing a vintage race car, and driving is all about fun, you need to decide what level of harmonics are you willing to live with to outrun all of your friends.Thank goodness track days only run 5-15 laps, then you get a break.677'