Create A Forum Installed
0 Members and 1 Guest are viewing this topic.
Yep, 16mm above ground he said. Btcc engineer and lecturer in automotive engineering. Rear is 40mm.
Now, where is the roll center in a twist beam system? It is not at the height of whatever provides lateral location, except in the case where the twist beam is exactly in the axle plane (the vertical, transverse plane containing the wheel axis). To locate the roll center on a drawing board, here's what we do: in a side view of the system, draw a vertical line from the center of the trailing arm pivot down to the ground. Insert or establish a point where this line meets the ground. We're going to call this point A. Draw another vertical line from the wheel center to the ground, and also upward a ways from the wheel center. This represents the axle plane, in edge view. Draw a third vertical line through the twist axis of the beam or deDion tube. This represents the twist axis plane (the vertical, transverse plane containing the twist axis), in edge view. Now find the lateral force coupling point between the twist beam assembly and the sprung structure. Note that this is usually not the roll center, but it is a definable point. In a VW Rabbit/Golf rear suspension, it is the trailing arm pivot. In the Rover system, it is the diff axis, or more precisely the inboard U-joint center. In the Mercedes W125 system, it is the center of the roller. Draw a horizontal line from this coupling point to the axle plane. Insert a point at that intercept. We're going to call this point B. Draw a line passing through points A and B, long enough so that it passes through the twist axis plane. Find the intersection of this line and the twist axis plane, and insert or define a point there. We're going to call this point C. The height of point C is the roll center height. In the Mercedes or the Rover system, point C will be above point B. In the VW system, point C will be below point B.
Fill y boots bud. Cad has to be better than my scribble. It would be nice to know rc's at different angles of beam/ as the suspension moves. Checked front rc notes....that was 16mm he said. Which i agree doesnt sound right the way we are thinking about them, but the guy should know his onions.....maybe there is something not being understood. I will see if i can get hold of him again.