Fitting Perspex Headlight Covers to a 105 Spider: The Full Guide

Perspex headlight covers change the look of a 105 Spider's front end more than any other single part. Fitted to a Junior, a USA-spec Series 2, or a Series 3 or 4 car, they give it the faired-in nose of the Duetto, roundtail and European Kammtail Spiders. A competent home mechanic with a welder can do the conversion over a weekend. The headlight bowl moves back and mounts on the inside of the wing on three welded studs, and slots are cut in the wing to locate the cover.

European Duetto, 1750 and 2000 Spiders left the factory with covers and the bowl already set back. Spider Juniors, USA-spec cars and all Series 3 and 4 Spiders have the bowl further forward, so they need the work below.

Allow a full day per side the first time, plus drying time for the paint. You'll be welding, cutting and painting bodywork. If you're not confident with that, any bodyshop can weld the studs and cut the slots, and you can do the rest yourself.

Do this before a respray if you can. Welding the studs on the inside of the wing will almost certainly burn the paint on the outside.

Parts you need from Classic Alfa

The core kit for one car costs £131.00 at current prices. Order it all at once so you're not waiting on a part halfway through.

Worth replacing while you're in there:

Cars with covers don't use the LT004 headlight seal, so you won't need one.

If the metal is rotten once the bowl is out, we stock left (ST121) and right (ST122) headlight support panels for 1970 to 1993 cars. They sit on the inside of the wing, behind the headlight aperture.

Tools and consumables

• MIG welder (or a stud welder) and welding PPE
• 3 weld-on threaded studs per side, with matching nuts and washers
• Drill and bits, centre punch
• Small cutting disc or air saw, plus needle files for finishing the slots
• Masking tape, marker pen and a card template
• Wire brush, panel wipe, etch primer, matching top coat and cavity wax
• Screwdrivers and spanners to remove the existing headlamp and bowl
• Somewhere to aim the headlights afterwards, or a garage with beam-setting equipment

Step-by-step conversion

Do one side completely, then repeat it on the other so both lights end up identical.

1. Disconnect the battery and remove the headlamp. Take out the retaining ring and headlamp unit, unplug the wiring and pull it back through the bowl grommet.
2. Remove the existing bowl. On cars without covers the bowl and its support sit further forward in the wing. Unbolt them and keep the fixings. Check the metal behind while it's exposed: this is a common rust spot, and any repairs (ST121/ST122) need doing before you go further.
3. Offer up the cover and mark the slots. Hold an LT031 cover in place and mark the two slot positions, one either side of the headlight. Each slot takes an LT033 grommet, so you need four per car. Mark the hole for the LT032 hook screw at the bottom of the cover at the same time. These cars were hand finished, so no two wings are quite the same. If the cover doesn't sit flush, trim its edges first, then mark.The two slot locations, one either side of the headlight. The chrome hook fixing sits at the bottom of the cover.
4. Cut the slots. Drill the ends of each slot, cut between them and file to size. The LT033 grommet should push in snugly. Take metal off a little at a time, because you can't put it back. Drill the hook screw hole while you're at it.
5. Weld on the three studs. The bowl now mounts on the inside of the wing aperture, further back than before. Use the bowl's own mounting holes as a template to mark the three stud positions, at roughly 10, 2 and 6 o'clock (see the photo below). Clean each spot to bare metal and weld the studs on square to the panel.The wing aperture with the bowl removed. The arrows mark where the three studs go.
6. Treat the bare metal. The welding heat will probably damage the paint on the outside of the wing. Grind the welds flush where needed, then etch prime, top coat and cavity wax the inside of the wing, the stud bases and the slot edges. Let it all cure before you fit anything.
7. Fit the bowl. Mount the bowl on the three studs with nuts and washers. Use your original if it suits, or a new LT109. Feed the wiring back in.The bowl in its new position, held on the three welded studs.
8. Fit the headlamp and dress ring. Install the headlamp unit with its retaining ring, then fit the LT005/1 thin dress ring to the aperture.
9. Fit the cover. Push the LT033 grommets into the slots and locate the cover's tabs in them. Secure the bottom of the cover with the LT032 hook and screw, with the kit's rubber pad under the hook.
10. Aim the headlights. Moving the bowl changes where the beam points, so re-aim both lights, ideally on proper beam-setting equipment.

Tips and common mistakes

• Test-fit the cover, bowl and headlamp with the bowl held in its new position before you weld on any studs.
• Don't overtighten the hook screw. Perspex cracks easily, and the rubber pad is there to spread the load.
• Clean the covers only with plastic-safe products. Solvents and paint polishes can craze perspex.
• Expect some fettling. The cars were hand finished, so the cover edges may need shaping to fit your wing.
• Check the rules where you drive. Covers were never fitted to USA cars because of the regulations there. In the UK the beam still has to pass the MOT with the cover on, so have the aim checked after fitting. Tell your insurer about the modification too.

Ready to start?

Everything in the parts list is available at classicalfa.com. We ship internationally, including to the EU, Australia and the USA. If you're not sure which parts suit your car, send us your chassis number and we'll check.

Further reading

• S2 Spider headlamp cover install photos on the AlfaBB forum