The club where I race uses timber track markers which can take a heavy toll on the car
However the PW bumper has helped a great deal and I find that lower arms can have large cracks in the cross members and still be good for up to 5 meetings before they break
I find that the castor blocks are teh worst for braking with this type of track marker, although I have managed to drive a whole 5 minute race with one of them broken with a bit of compensation for the understeer this induces
Dan