Vent Glass Replacement for Lotus Elan (S1/S2/S3/S4) 1962-1973 by Alexwindshield

Understanding the Two-Seater Window Architecture vs. Elan +2

If you are searching for front vent glass on an Elan roadster or drophead coupé, you will quickly discover that your door does not have one. The classic two-seater sports car—spanning the original S1, S2, S3, S4, and the final Sprint variations across Types 26, 36, and 45—was engineered by Colin Chapman's team with a uninterrupted, single-pane side glass. That single sheet of glass raises and lowers directly inside the door opening without a forward division bar or triangular quarter light.

The only variant from this family that actually incorporates a front vent window is the longer four-seater Lotus Elan +2 (Type 50), which arrived in 1967. Inquiries for vent glass on standard S1 through S4 cars typically originate from confusion with this stretched sibling. On the +2, Chapman added a fixed triangular pane in front of the primary winding glass to improve cabin air routing and allow a wider door aperture without a massive, unsupported drop glass.

Glazing Construction and Factory Part Identification

The quarter glass fitted to the Type 50 door assembly is a stationary, non-opening triangular unit. Unlike many classic British roadsters of the sixties that used pivoting draft deflectors on friction hinges, this glass is fixed firmly in place. It carries no defrost traces, internal antennas, or modern bracketry; it relies entirely on its surrounding frame for structural integrity.

Factory production supplied this glass through Triplex as toughened safety glass, offered in either standard clear or Sundym green tint. Because these cars were hand-built in low production volumes in Hethel, they sit entirely outside modern North American NAGS cataloging systems, making original factory reference numbers vital when sourcing replacement panes.

Surrounding Brightwork and Frame Channels

The stationary pane is secured within a delicate, bright stainless or chrome perimeter door frame assembly (factory parts 050B0789 for left hand and 050B0790 for right hand). A vertical division bar—often called the silent channel—stands between this stationary pane and the main roll-up window, serving double duty as the rear border for the quarter seal and the front glide path for the sliding side window.

When you need work done on these fragile British frames, I can typically be at your location roughly an hour after your booking to examine the glass and metal assembly directly. Along the bottom, the glass nests into a specialized lower channel (parts 050B0857 and 050B0858). Because moisture naturally runs down the face of the glass and collects in this bottom pocket, these lower channels and the adjacent frame miter corners are notorious for advanced hidden corrosion, often requiring careful repair before fresh glass can be seated.

Rubber Glazing Retention Challenges

Securing the pane into the bright metal frame relies on specific lengths of continuous rubber glazing strip (commonly divided into 7-inch, 15-inch, and 20-inch sections depending on the frame run). The combination of narrow channel tolerances and firm modern rubber extrusions makes seating the glass exceptionally difficult. The rubber tends to squeeze out of the channel under pressure, forcing the glass out of square with the vertical drop channel.

Restoring these assemblies requires constant lubrication and gradual mechanical tension using padded parallel-jaw clamps or strap vices to draw the channel walls over the rubber without introducing point-stress to the tempered glass. If the quarter pane is seated even two millimeters out of alignment, the vertical silent channel binds against the main drop glass, preventing the main side window from operating smoothly inside the door.