Who ever suggested that you should get a few inches of movement by pushing down on the front wings has something wrong (with the wings), there is barely a few inches of bump travel anyway.
There are two BIG problems of trying to push down on the front to get the front springs to give:
1. If you are running with a compressed rebound spring your initial rate will be around 400 lb/inch or more (125 lb/inch main PLUS 275 lb/inch rebund typically). So 800 lb/inch for the front of the car. I weigh 80 kg = 176 lb. So the suspension will move in bump if I stand on the front bumper by 176/800 = 0.22 inches!!!!!!!!!!!!!!! or 6mm, oh that is noticeable then?
AND
2. When you try to push down or lift the front of the car the wheels need to move outwards at the same time, so the high tyre sidewall stiffness ADDS to the vertical rate - when stationary(ok when rolling)! So it is easier to do this test on older cars with soft 80% aspect ratio tyres, than on later cars with lower profile tyres and high tyre pressures. Put one wheel on a Trakrite (for setting toe) and try again and watch. The change in track in bump is quite significant, try measuring you toe angle with an empty car and one with two people just rolled into the garage!
Regards PJB.
