The plastic rear window is the weak point in any convertible top. Plastic windows scratch easily and discolor with age. Our experience in Northern California is that plastic windows last in the 2 to 4 year range with average care. That is much less than the surrounding top material. An opaque plastic window can be a safety hazard as well as an annoyance.
Like Humpty Dumpty, once window plastic goes bad no repair process can make it good again. Happily, a bad plastic window doesn't mean the entire convertible top must be replaced. Many times it is possible to replace the plastic by itself.
The traditional way to replace plastic windows is to remove part or all of the convertible top and sew in new plastic to replace the old. This is the way it still needs to be done on most cars, to include Porsche Boxsters, Mercedes, Hondas, Nissans, and Mazda Miata. As long as the surrounding canvas or vinyl material is in good shape, this is an excellent way to restore a top to serviceable condition for much less cost than full replacement.
When we sew in windows we have two plastic options. For years the standard rear window was made from 40 mil PVC-based plastic. This plastic is durable and inexpensive. However, it scratches and browns easily. It also cracks because it gets brittle with time. Fortunately, a new urethane-based plastic, TPU, recently became available. TPU was developed in Switzerland by BMW for use in the convertible tops of their high-priced Z8 Roadsters. TPU plastic is more expensive, but formulated to maintain flexibility and be vastly more resistant to scratching and discoloration. It is not PVC-based and thus does not have problems with plasticizers leaching out of the plastic. With proper care it is designed to last much longer than PVC-based plastic.
Certain BMWs, Porsches, and Audis have plastic rear windows installed with an updated zipper system. The zipper systems are designed to make plastic window replacement much faster and easier than in the past. The bad news is that these replacement windows are proprietary dealer products and are therefore expensive. Some of them can only be installed at the dealership. Also, these windows only come in PVC-based plastic.
Finally, for some convertibles it is possible to replace a plastic-window top with a glass-window top. This is a great option when available because a glass window will last the life of the car and requires much less work to keep clean and clear. Ask us about glass window replacement for your Porsche, Honda, or Mazda Miata. Also see our Convertible glass window repair and replacement page.
If youre having trouble with your plastic rear window stop by to see us in Santa Clara. We'd be glad to go over all the options to solve your problem. Estimates are always free. We can set up an appointment for your visit or you can stop in at your convenience. Check the How to find us section of this website for our hours and directions.
Premier serves the entire San Francisco Bay Area from our location in the South Bay. We would be pleased to serve you whether you live in San Francisco or Santa Cruz, or someplace closer like San Jose, Sunnyvale, Mountain View, Palo Alto, Campbell, Los Gatos, Saratoga, Cupertino, Los Altos, Milpitas, Newark, or Fremont.
Visit the convertible top care section of our Convertible Top and Interior Care Guide for information about cleaning and taking care of your plastic rear window.
Auto services: Replacement of Convertible Tops, Convertible top repair, Convertible plastic window repair/replacement, Convertible glass window repair/replacement, Convertible top frame, motor, and mechanism repair and replacement, Breaking in a new convertible top, Ten stupid convertible top tricks, SUV tops, Vinyl and landau tops, Tonneau covers, Seat repairs, Headliners, Carpets, Leather interior conversions, Enhancing seat comfort, Interior dash trim, Synthetic suede