If you have the early style S40, you have to disconnect the boot from the know, then pull the shifter knob straight up. This can be tricky since they are very tightly pressed on the shifter. You have to grab it tight, and pull quickly upwards in one quick motion. Getting the new one one can be tricky too. The new knob from Volvo can be very tight and sometimes needs a little modification with a file to get it to go on correctly. Good Luck!