What he said exactly, I have gathered a ton of different sources and drawn my own conclusions from them.Get some more books. You don't want to take just one road racing book and base your entire build on it.
There is some good info here (that came from an old "Chevy Power Manual")
http://www.pirate4x4.com/forum/gall...=25&orderby=title&direction=ASC&cutoffdate=-1
For a solid axle don't forget that the wheel rate is different depending on 1 wheel bump or 2 wheel bump (as if it wasn't complicated enough already).
Dave, your explanation is close, but it doesn't tell the whole story. Motion ratio can be looked at two ways. The overall motion ratio is the total vertical wheel travel/total shock stroke. However, motion ratio is neither constant nor linear. Motion ratio varies throughout the suspension travel, so at any given point in the travel, you would have an instantaneous motion ratio. Hopefully, that would be a progressive ratio, i.e. 3:1 at full droop and 1.5:1 at full bump. When plotted out, motion ratio should be a progressive curve (rising rate)."Motion Ratio" or installation ratio is found like this.(also you can go to sway-away.com and go to the tech room and they have online calculators and cool diagrams, a little confusing for the layman I think. Say I have an A-arm front suspension and I am looking at it from the front. For argument sake lets say the A-Arm mounts on the upright at the wheel center line, and the arm length from pivot to pivot is 20". Now lets say that the coil over mounts completely vertical at 12" on the arm as measured from the chassis pivot. All you do is simply divide the length of the coil over mount from the chassis pivot by the total length of the arm. So 12/20 which comes to .6, that is the ratio of spring/shock movement to wheel movement. So lets say the wheel bumps up 1 inch, well the shock will only move .6" inches
Cool. . .thanks for that info. . .I knew what it was I just wasn't calling it that. . .we had to figure that stuff out for our buggy to make sure that we got the travel we wanted without tearing the shock apart or wasting shock stroke. . ."Motion Ratio" or installation ratio is found like this.(also you can go to sway-away.com and go to the tech room and they have online calculators and cool diagrams, a little confusing for the layman I think. Say I have an A-arm front suspension and I am looking at it from the front. For argument sake lets say the A-Arm mounts on the upright at the wheel center line, and the arm length from pivot to pivot is 20". Now lets say that the coil over mounts completely vertical at 12" on the arm as measured from the chassis pivot. All you do is simply divide the length of the coil over mount from the chassis pivot by the total length of the arm. So 12/20 which comes to .6, that is the ratio of spring/shock movement to wheel movement. So lets say the wheel bumps up 1 inch, well the shock will only move .6" inches
If you were to plot the curve at from full bump to full droop then the shape of the curve would look like the right half of the letter "U" right? or would it be the opposite (meaning instead of being concave the curve would be convex. . .like if you flipped the "U" upside down. . .)?Dave, your explanation is close, but it doesn't tell the whole story. Motion ratio can be looked at two ways. The overall motion ratio is the total vertical wheel travel/total shock stroke. However, motion ratio is neither constant nor linear. Motion ratio varies throughout the suspension travel, so at any given point in the travel, you would have an instantaneous motion ratio. Hopefully, that would be a progressive ratio, i.e. 3:1 at full droop and 1.5:1 at full bump. When plotted out, motion ratio should be a progressive curve (rising rate).