Remove the handlebar mirrors from the Vespa by grabbing each mirror at the base and turning it counterclockwise until it unscrews from the from the headset frame of the scooter. The headset frame consists of the handlebars, headlamp support and dash of the scooter. Remove any aftermarket parts you have added to the headset frame, such as extra mirrors and front carry racks.
Place the windshield brackets in position on the headset frame so each bracket lines up with the thread holes in the frame designed for this purpose. These thread holes will look exactly like the handlebar mirror thread holes but will sit lower on the headset frame, underneath the handlebars. Place the bracket bolts in the thread holes, then turn them clockwise a few times---just enough so the bolt will hold the bracket in place but so the bracket remains loose.
Slide the windshield support arm (a metal tube with bolt holes) through the brackets. Center the support arm on the headset frame so equal lengths of the arm extend on either side of the headlamp. Rotate the arm so the bolt holes in the arm face outward from the front of the scooter. Tighten the bracket bolts using an 8mm box wrench to hold the support arm in position.
Rest the windshield so the curve at the bottom covers the top of the headlamp casing. Line up the bolt holes in the windshield with the bolt holes in the support arm. Make any adjustments necessary until they match.
Slide a rubber washer onto each of the windshield bolts, then push the bolt through the windshield and support arm. The rubber padding will prevent the bolt head from touching the windshield. The mounting hardware that comes with the windshield should include these washers.
Tighten the lock nuts onto the end of the windshield bolts. Hold the bolt head in place with a crescent wrench while tightening the nut with the 8mm box wrench. Tighten the nut to hand tight; do not overtighten the nut, or the windshield could crack.
Reinstall the handlebar mirrors and any other aftermarket accessories you removed prior to placing the windshield.
