If you're lucky enough to have the wiper arm come loose like I did here; or you want to adjust the angle of the wiper on your car; or you want to paint the wiper arm; perhaps the LP640 arm is more appealing to you than the Murcielago arm. Whatever the case is, here's how to get the arm off and on again.
1. Remove the trim cover by removing the small hex bolt and lifting the trim cover off;
2. Remove the 17mm retaining nut;
If you're only adjusting the arm, this is where you move the arm to a desirable position, re-tighten the retaining nut and install the trim cover.
3. Remove the small black trim piece covering a 21mm retaining nut;
If your car has a washer fluid sprayer on the wiper arm, pull the washer hose from the wiper arm at this time.
4. Remove the 21mm retaining nut;
5. Lift off the wiper arm;
6. Install the new wiper arm;
7. Install the 21mm retaining nut and trim piece;
8. Install the 17mm retaining nut; and
9. Install the trim cover.
Murcielago Wiper Arm and Blade
LP640 Wiper Arm and Blade