Forces at Bellcrank

For calculating loads at the bellcrank we can use the pushrod force and make some assumptions. We assume that:

• We are using the worst pushrod loading case, which occurs in the front outside pushrod for the conditions above.
• Forces balance out
• All force is in the Y-Z plane
• The coilover node is 1.75x as far as the pushrod node (overestimation, actually 1.72)
• The bellcrank-chassis joint provides no moment about the X-axis
• Full coilover compression occurs at 40mm from the coilover’s neutral 1g position
• When the coilover is fully compressed its behaviour changes from a spring (resists force based on displacement) to a rod (resists all force)
• The worst loading condition is when the coilover is fully compressed

*Note: in some scenarios, it is possible that the loading is worse when the net force vector points directly away from A. While the magnitude will be less, the force will be borne by the weakest part of the bellcrank. However, based on rough calculations the force is not significant until the coilover is fully compressed.

Given the angles and magnitudes above we can find the normal and tangential components of both forces relative to A, knowing that the bellcrank has no moment in the X about A when fully compressed.

We can translate these forces into our more convenient Y-Z axes.

To maintain static equilibrium, the forces at A must oppose all forces at B and C.