We always knew people could get very creative with cars like the Lotus Elise. Dave Gittins is one of those people.. He designed and made a Mesh Screen instead of a rear window..

Here's the full Mesh Screen story..

Introduction

This document describes how I made and fitted a black, aluminium mesh screen, to replace the rear window on my Elise 111S. At the end are some comments.

The main aim was to eliminate the irritating squeak common to the glass window. I was also interested in improving ventilation of the cockpit with the top fitted. There also seemed to be the potential in cars used for racing  to save weight, while at the same time providing a barrier to track debris, without compromising visibility or security.

there is a flange on the car body/roll-bar cover originally designed to hold the glass. Total cost was about £30, including £11 for the metal cutters. Finding the parts took weeks, but doing the cutting, edging and fitting took only about 45 minutes.

This seemed to get rid of the squeaking. The grille has been tested in a variety of road conditions and there have been no problems. Even under torrential rain, water hasn't come into the cockpit. I haven't tried it on a track or for racing, nor attempted to paint a decal or logo on the screen. The mesh is pretty firm, and doesn't seem to flex. It does let heat from the engine into the cockpit, but not as much as when you remove the window completely. So it is probably well-suited to winter driving: providing additional cockpit heating, combined with being a secure alternative to glass. If you're a committed racer, it definitely saves a significant amount of weight.

Disclaimer: I do not take any responsibility for the consequences of you installing your own grille. I have no idea whether this constitutes a change required to be notified to your insurer, nor whether the design conforms to legal/racing requirements for equipment, visibility, etc. This hasn't been tested by Lotus and isn't in any way endorsed by them, nor is there information on how it might affect handling, airflow, or aerodynamics.

The Original Window

The original window assembly on the later Mk-1s comprises an angled sheet of glass in a larger, vertical frame. This is held in place by four small flanges, two on the bodywork behind the cockpit, and two on the inside of the roll-bar cover (RBC). The RBC is attached by two clips to the bodywork, is removed by undoing these, and has a front and back.

Early Elises had two problems with this assembly, firstly, the clips were badly sited, so that the RBC would come off, especially with the glass removed. Secondly, the window glass was initially not angled, and reflected the headlights of oncoming cars into the driver's mirror. Most Mk-1s. now have re-sited clips, and angled glass in the window, correcting these respective problems.

The Mk-1 Elise has a notorious 'squeaking window', which can often be heard above the sound of the engine. In my opinion, this arises from the fact that most of the 2 metres of rubber edging touches the bodywork, but is free-moving, and not held firm. It's only at the four small bodywork flanges that the window is held tightly. My initial idea was to make the edges as thick as the original glass/rubber window (15-20mm). Fortuitously, having to use the thin (8mm) rubber edging (designed for door protection) worked well , because the edge now doesn't actually touch any of the bodywork, other than at these flanges.

With the glass in, there have been cases of stones shattering the window, because of a back-draught in the air pattern over the cockpit. People opt to remove the glass in the winter, because it gives improved warm airflow in the cabin. Racing owners also tend to remove the glass for better visibility, and to reduce weight. If you remove the glass, you get two interesting airflow effects: firstly, rather too much heat from the engine will enter the cockpit, and secondly, road/track debris can also get in. You might want to replace the glass with a mesh for any of three reasons: (1) to eliminate that annoying squeak (2) so that some warm air comes in and (3) to lose weight. A mesh stops debris getting in, while keeping the inside secure.

Tools & Materials
 

• Mesh Screen: 300mm x 1,000mm
• Rubber Edging: 'U' profile – 2.5 Metres
• Metal Cutters

Mesh: Motor factors and car accessories shops sell mesh intended for air intakes. This comes in a variety of patterns (circular holes, lozenges, oblongs, etc.), and as far as I saw, the colour is either as bare aluminium, or painted black. I used the same lozenge-shaped cutout as on the original Lotus engine vents, which are in black. There was almost no choice of gauge size. It may be that a smaller gauge will flex too much, anyway. Cost was about £14.

Edging: All I could find with a 'U'-shaped profile was door protection rubber, in a maximum 1 metre length. So this is what I used, leaving the sides of the grill bare. At some time I'll go back and put rubber all-round the full 2.25 Metre circumference.

The following sections describe the main steps in making and installing the grille.

Photo(1) Mesh & Window
Original oblong mesh grille, as bought from local motor factors shop. 900x300mm was biggest in stock, but really needed to be 1,000x300mm. Note the external side has a sticker on the window.

Step-1: Note the important aspects of the glass window and remove it

1. On my car, there's a 'Lotus Alarm' sticker facing the outside (see 'photo).
2. Undo the hinges at each side of the roll-bar cover and remove the cover.
3. Slide the window out.

Step-2: Cut out the mesh

(Note: If you're confused about which profile to cut, it's the one which forms the largest shape.)
4. Lay the window flat, with the external side facing downwards (see below).
5. Lay the mesh on top.
6. Cut the mesh to the same profile. Being right-handed, I had to cut clockwise (this distorted the waste mesh, rather then the grille, as I cut round).

Comments

'U'-shaped Edging: The circumference of the replacement is about 2.25 metres and ideally, you'd get a 2.5 M length if you could (I used two, 1M lengths, only because that was all the shop had in stock). One thought I've had subsequently is that it doesn't really have to be 'U'-shaped at all – for most of the circumference it does not actually sit on the bodywork. As with the original window, all you need is something on each side, perhaps with a slight overlap to protect the cut edge of the grille.

Mesh Size: The gauge of my mesh is a bit big, in comparison to that used on the engine covers. I'd probably go for something with a slightly smaller mesh. However, my mesh is pretty stiff, yet light, and you might lose some rigidity using a smaller mesh size.

Flange Spacers: I've just used some foam. But it would be more elegant to use a thicker rubber 'U'-shaped edging at the flanges. Again, I couldn't be bothered to search for this.

Air Intakes: The mesh that I used is designed for air intakes. I wonder whether the front, and rear side-vents wouldn't look good if you matched them all using the same mesh as the window replacement? Just a thought. You could also try covering the driving-lights with a complete replacement oval front grille. However, you'd have to be sure you could get the same airflow through as with the existing open design.

Colour/patterns: Most of the mesh that I saw came in either bare aluminium, or black. If you were keen, you could try to colour-match the paint with the bodywork. On my 111S, though, the original air vents and engine cover mesh are black, so aluminium would have looked odd. There are also other patterns, but again, I chose to match the cut-out used on the engine bay grilles. I would like to put a Logo on the mesh somewhere, and this should be no great problem, other than making the stencils. Racers should be able to paint decals on pretty easily.

Outer side of Window: You need to indicate to yourself which is the outward-facing side of the window, in order to cut the grille properly. I used a 'Lotus Alarm Fitted' sticker that was already there. You'd need to write or stick something on if there's nothing to indicate this.

Dave Gittins, July 2001