A fuel cell includes a fuel cell stack. A pressure plate is arranged on one side of the fuel cell stack. The pressure plate includes a hole, and a tie rod assembly has a tie rod received in the hole. A nut with a conical surface is secured to the tie rod. An isolator is arranged in the hole between the tie rod assembly and the pressure plate. The isolator has a conical portion, and the conical surface engages the conical portion to provide a conical interface. The tie rod assembly applies a clamp load on the fuel cell stack via the conical interface.