Replacing the windscreen: glass or plastic? 

Differences, replacement options, service life and glass colour

A clear view to the rear in a convertible isn’t a luxury, but a safety feature. However, over the years, the plastic window may become cloudy or cracked, or – in the worst-case scenario – detach from the fabric. At that point, at the very latest, the question arises: should the soft top be replaced, and can the window be replaced separately? Glass or plastic – what replacement options are available, and how long does the whole thing actually last? This is precisely where it’s worth taking a closer look.

Why the soft top windscreen is so important

The plastic panel is one of the parts of the convertible top that is subjected to the greatest wear and tear. It is folded and stretched, and is exposed to the sun, cold, damp and mechanical stress. Minor scratches, creases or material fatigue build up over time. The consequences range from restricted visibility to leaks.

Plastic disc: flexible, lightweight, classic

Plastic windscreens, usually made of PVC, are particularly common in older convertibles. They are regarded as a classic solution as they are lightweight, flexible and space-saving. When the soft top is opened, the soft windscreen folds away easily into the soft-top compartment.

It is generally not possible to fit a glass panel in these vehicles. The soft-top compartment does not offer sufficient space for a rigid panel; furthermore, the soft-top frame, which is often quite delicate, is not structurally designed to cope with the additional weight and the altered load.

For many classic and modern classic cars, plastic windscreens are therefore the only technically sound solution that is also true to the original. Anyone wishing to preserve the historic character and functionality of their vehicle has no choice but to opt for a high-quality soft windscreen.

Glass pane: durable, comfortable, modern

Modern convertibles are often fitted with integrated glass panes made of real glass, many of which feature a rear window heater. The main advantage lies in the consistently clear view, as glass, unlike plastic, does not yellow or become cloudy. Furthermore, the material is significantly more scratch-resistant and dimensionally stable, which has a positive effect on the vehicle’s appearance and long-term value retention. Thanks to these properties, a glass pane generally has a significantly longer service life and can easily last ten years or more.

However, there are also a number of limitations. Glass panes are less flexible than plastic and are therefore not suitable for every soft-top system. Particularly in older convertibles, converting from plastic to glass is often technically impossible. Added to this is the increased weight, which must be taken into account in the design of the soft top. For this reason, before replacing the soft top, a professional assessment should always be carried out to check whether the soft top is structurally designed to accommodate a glass panel. This is the only way to ensure that functionality, fit and watertightness are maintained in the long term.

What types of rear window fixings are available?

Sewn-in plastic disc

With this method, the plastic panel is sewn securely into the existing soft top. This method is particularly robust, often corresponds to the manufacturer’s original design, and ensures a permanently watertight seal. However, it requires a great deal of craftsmanship and experience, as the seams must be executed with precision to remain permanently watertight.

An additional zip on the inside of the rear window did not prove effective in practice. For this reason, car manufacturers abandoned this solution after only a short time.

Furthermore, a plastic panel changes over the years: it shrinks and loses its original dimensions. As a result, a new panel will not simply fit into the existing opening in the old soft top. To ensure a precise, tension-free fit, the new panel would therefore need to be sewn into the existing soft top to measure, which is often not economically viable.

Laminated glass panel

With this method, the glass panel is fitted using special adhesives. It is used in most glass-panelled roofs and in newer designs. The key factor here is the original equipment manufacturers’ many years of expertise regarding adhesives, temperature and pressure, to ensure that no leaks or delamination occur.

Service life: more than just a question of materials

Whether made of glass or plastic, the lifespan of the windscreen does not depend solely on the material. These factors also play a major role:

• How often is the soft top opened and closed?
• Is the soft top operated when the temperature is below freezing?
• How well is the screen maintained?
• Is the convertible used all year round or mainly in the summer?

Plastic windscreens, in particular, should never be folded whilst cold in winter. The material becomes brittle and tears easily. At KHM, customers can also request care advice to ensure their new windscreen remains clear for as long as possible.

Rear window colour: clear, green or grey?

One aspect that is often underestimated is the colour of the windscreen. It affects not only the car’s appearance but also driving comfort.

Clear windscreens offer maximum visibility and have a very classic look. Ideal for classic cars and those who love the original look.

Green-tinted windows reduce glare and complement the look of many modern vehicles. Often found on glass windows, but sometimes also on plastic windows. Depending on the original specification.

Tinted grey windows are only available for glass rear windows and give the car a sporty look whilst offering a little more privacy. They are particularly popular on newer convertibles.

Questions about convertible tops? KHM offers advice on all makes and models

At KHM Cabrioverdecke, we always focus on softtops as a complete system. Windscreens are an integral part of modern convertible tops, but are not replaced separately. We’d be happy to advise you on general queries regarding convertible tops, materials, care, lifespan or the condition of your top – regardless of whether your vehicle is classic or modern.

If you have any questions or suggestions regarding softtops, please feel free to contact KHM at any time. You can easily reach us by email atkhm@cabrio.de or by telephone on+49 711 35 79 000.