My 16 year old son has bought a car and, as the young often want to do, desires the largest rear wing available for it - the one fitted to the STi version.
His car is a 2002 Subaru Impreza RS, like this one:
Note that it already has a rear spoiler.
This is the wing he has bought:
It does appear to have an actual wing profile, and the end plates should act as fins, moving the lateral centre of pressure backwards.
This convinced me to donate $100 to the project, if I could aero test the car. The agreement was made, and so today I fitted a rear suspension height sensor to his car.
I use P38 Range Rover suspension height sensors - about 20 pounds (US$25) each on eBay UK.
Fitting is fiddly but not hard. I used two new 6mm balljoints (mine didn't come with the extra links). After this pic was taken, I slipped a piece of bike inner tube over the ball joints and link to keep the dust out.
I am using this circuit to smooth the output. It costs almost nothing and uses just a few passive components. The adjustment pot (being used as a variable resistor) adjusts the averaging time. It's needed to get an average ride height.
The 5V is supplied by a regulated cigarette socket phone charger and the signal is read by a multimeter.
I intend measuring rear ride height of the car with:
- no rear spoiler
- the small rear spoiler
- the large wing