So how does your suspension improve performance based on the oem summer tires.
I posted all the other data not to have a company measure it, but to see if they actually take the time to engineer their parts so they get the desired results for better handling.
I am not into the hatch world. However, I know that lowering and older mustangs will actually increase the snap oversteer because the suspension geometry was created wrong in the first place.
After saying all that, how do we know that the aftermarket suspension is actually improving handling performance?
One of the biggest thing you can do with adjustable coilovers is you are able to run a higher springs rate.
So for example, a normal OEM suspension wouldn't run close to 2.0Hz wheel frequency because it will be too harsh.
With an adjustable damper, you are able to run close to 2.0Hz and "get away" with it because you can adjust the damper to have a lower compression cracking pressure and that mean a more comfortable ride.
So the softer adjustment mean you have less body movement (due to the higher springs rate), but at the same time not major lost of comfort (due to the softer damping).
On the stiffer adjustment where you need the performance, the adjustable damper mean you can run close to "critical damping" and get the most out of the springs and tires.
On the Fiesta ST, the rear motion ratio is really high, and that mean it is very sensitive to springs rate and damping change.
The rear damper actually move MORE than the wheel.
Aside from wheel frequency, getting those right along with the damping, really are all that you need.
You got to make sure the front and the rear do not hit a suspension harmonic having the wheel cycle frequency too close (especially important on a road car with a full tank of gas).
You got to make sure in most case the drive wheel is the wheel with the lower frequency so it will generate more traction (there are exception so this is just a general rule).
Once you can work out the vehicle dynamics, you are about 90% there.
Yes, there are cases where you have odd balls, but those are few and far between.
If you get the math and the numbers right, you actually aren't far off most of the time.
Of course, getting the numbers right in the first place is actually the more difficult part.
Get the corner weight wrong? The final result is off.
Get the motion ratio wrong? The final result is off.
Customer buy a suspension designed for a race car with aero, then proceed to put it on this weekend road and track car?
The ride is going to be rubbish because the customer bought the suspension designed for a different use.
All those have to be taken into consideration.
In your case with the Mustang.
You have to look at everything holistically.
If you lower the car and the rear is going to be toeing out with no way to adjust it, bad idea.
If you lower the car with heavier springs rate with toe out and using a damper that isn't providing enough rebound force for the new springs rate... even a worst idea.
But once you get into alignment, contact patch, etc...
That is another field, and normally I pass that over to geometry specialist that I work with.
They are the person to make sure all the roll centre, camber, toe, caster, etc are what the driver want.
Because alignment is another thing that is very driver preference oriented, as in everyone like different things and you really need to work with the driver to get a setting that they like.
Jerrick
