Windscreen assembly: repair panel and complete assembly

What the windscreen frame comprises

The windscreen frame is the metal frame into which the windscreen is fitted: the lower crossbar, the two side pillars and the corner brackets connecting them. On most older models, it also forms a gutter that collects water from the windscreen and drains it away via two drains.

It serves both a structural and a waterproofing function. A perforated windscreen frame allows water to enter the passenger compartment, but it also weakens the windscreen’s anchorage, and thus the rigidity of the bodywork. This is why it is not sealed with sealant.

Why does the windscreen surround rust before the rest?

Three factors always combine in the same place. The drains become blocked with leaves and dust, and water pools in the gutter instead of draining away. The windscreen seal hardens and allows a trickle of water to seep through, working its way between the glass and the bodywork, hidden from view. Finally, the sound-deadening foam fitted beneath the dashboard traps this moisture against the steel.

The result: corrosion starts from the inside of the bodywork and is only visible at a late stage, when the paint starts to blister. By the time it is visible, the lower section usually needs to be replaced rather than repaired.

Repair panel or complete body section

• A corner or frame angle panel is sufficient when corrosion is localised at one end, which is the most common scenario. This is the most economical and discreet repair.
• The lower section repair panel covers the lower cross member, where water collects. It is butt-welded to the sound panel, retaining the original uprights.
• Replacing the entire frame is warranted when the uprights are affected or when the frame’s geometry has shifted. This is a heavy sheet metal component, which requires spot welding to the drawing and checking the diagonal dimensions.

The criterion is simple: as long as sound sheet metal can be used as a reference to reposition the part, a partial repair is preferable. As soon as the reference points are corroded, the entire frame must be replaced.

Ventilation flaps and seals

On many older models, the opening features a ventilation flap that supplies fresh air to the passenger compartment before any forced ventilation kicks in. Its seal is the second most common source of leaks in this area, just after the drains: once hardened, it allows water to enter directly above the driver’s feet.

The vent is sold as a complete unit, with its seal, trim and fixings, or as a seal only when the metal panel is in good condition. Replacing the seal alone is a one-hour job that fixes a leak often mistakenly attributed to the windscreen.

Clear the drains before welding

A new windscreen fitted onto a gutter that no longer discharges rust like the previous one. Before refitting, check that the drains are clear along their entire length by simply pouring water into the gutter and checking that it flows out.

Also make the most of the removal to treat the inside of the windscreen housing – which is inaccessible once the windscreen is refitted – and to replace the windscreen seal rather than reusing the old one. A new sheet of metal and a worn seal will produce the same result as before, just a year later.