
Very Bouncy suspension can often be caused by having a simple newtonian physics model with a low sample rate. For example, if you have a strong spring that is compressed you calculate the force  the distance the spring is compressed times the spring constant. You then divide the force by the weight applied to the spring (say 1/4 the vehicle weight  ignoring centre of gravity for the moment), and this gives you the acceleration rate that the vehicle will move off the suspension (it might be coming down at this point). Now, if you multiply that by your time delta (assuming the acceleration is constant**) it gives you a velocity, and multiplying that by you time delta gives you a displacement.
**Accelleration isn't constant. This leads to you over extending your spring if you time delta is too big, and producing oscillations, or forces that are greater than would naturally occur. There are two solutions:
1) have a tight looped bit of code where you do just the supension calcs. Divide you time delta by a couple of thousand, and to the loop a couple of thousand times, recalculating the spring compression, acceleration, and displacement each time with a really small time delta.
2) Use a non time based domain  e.g. Laplace Domain (pick up a 2nd3rd year Bachelor of Engineering Maths Book) for your physics model.
