Springs keep the ground down, but sometimes not down quite far enough. Then the vehicle ends up hugging the concrete under the oil pan and muffler. When engineers design a suspension, they expect a specific level and design the linkage geometry for that. If the height is other than the planned level, the angles between the links change, always for the worse. The only partial exceptions to this are very old vehicles with two solid axles and leaf springs, which just gradually sag. Even these antiques, however, show the first and most important symptom of suspension decline: As the springs sag, front toe wanders in or out depending on whether the steering arms lead or follow the axle.