4 Bar Link Calculator Version 3.0 Tutorial
Let's start with the Vehicle Specifications.
Most of these should be obvious. If they aren’t don’t read any farther.
Vehicle CG Height: To measure this you will need access to some accurate scales. See
www.jeepaholics.com for the procedure. A quick guestimate is to measure the top bell housing bolt height from the ground. This way however, is an approximate of the Sprung Mass CG Height (2nd tab).
Unsprung Mass: With the wheels on the ground this is everything that does not move if you bounce the body of the vehicle up and down. Some parts will have one end that will move up and down and one end that will not (like shocks or the links themselves). These parts are generally considered with half of their mass as unsprung mass. The best way to measure this is to unbolt the parts (tire/wheel, rear axle, shocks, etc.), weigh them individually, and add them all up.
Park your vehicle on level ground
Remove the rear tires and support the axle with jack stands at operating height if you need the clearance to climb under the vehicle
Use a plumb bob from the center of the axle tube to the ground on each side of the vehicle. Mark these points with chalk on the ground and draw a line between them.
Measure the distance between the marks, divide by two and mark the center. Now use a large square to mark a line under the center of the vehicle or do the same thing in the front and connect the dots.
Now start looking for places to put your links. When you find places you like drop the plumb bob from there. Measure from the transverse line (the one under the rear axle) to where the plumb bob meets the ground. This is your “X” value. Now measure from the longitudinal line (front to back down the center) to where the plumb bob meets the ground. This is your “Y” value. Now measure the length of the plumb bob from the point you picked for the suspension to mount to the ground. This is your “Z” value. Do this for both ends of both links on one side of the vehicle.
After you have these measurements (some basic and some far from it) enter them all into the light blue cells on the main page.