Quote:
Originally Posted by BadAzSolstice
Forgive me for being ignorant, but what is the deal with a 7% versus 5% incline?
Because the body of Solstice is low to the ground, when you approach an inclined ramp from a flat surface, the nose of the vehicle may wind up touching down on the ramp before the tires start climbing the front of the ramp sufficiently to keep the nose from touching, like this:
Similarly, when going over a bump or "kink" where the ramp levels out, you can scrape the center of the car as the front wheels proceed out along the straight part before the rear wheels have lifted the center of the car sufficiently to avoid the "peak" of the ramp. In off roading, this is called "high centering" and it occurs when the curvature at the top of an obstacle is sharper than the ground clearance will permit the vehicle to clear, like this:
To eliminate these problems, you can do 3 things.
- you can decrease the "overhangs" on the front and back (the amount the nose and tail protrude past the wheels)
- you can decrease the wheel base (bring the front and back wheels closer together)
- you can increase the distance from the bottom of the vehicle to the ground by raising the suspension and increasing the height of the tires.
Doing the first (decreasing the overhangs) has some advantages, but the second (shortening the wheel base) can reduce high speed stability. The third (raising the suspension and increasing the height of the tires) has two negative effects:
- Increasing the height of the center of gravity and changing the roll center of the vehicle
- Increasing the amount of air that goes under the car thereby increasing rolling resistance through increased drag.
The advice to be careful about speed bumps is well taken, because even if the speed bump is only 3 inches tall, you must gently lower the front and rear wheels down from on top of the bump to avoid the jounce and concomitant suspension compression which will actually cause the car to spring lower on it's suspension and potentially bounce down onto the speed bump.
For inclines, this also matters for a driveway: If the driveway apron is very steep, and fairly short, you can wind up scraping the nose, and the underside between the wheels as you drive into the driveway. The same holds true for parking lot entrances, so caution will be well advised for transitions from the street up driveway aprons and back again.
Hope this helped a bit.