HARD TOP DOME LIGHT MOD

by Dez Cross - prado@slingshot.co.nz

For this mod I used a Perei 4-Led unit, 8 - 24V DC, Part Number FM60CB. The white unit measures 63 x 34 mm and the black bracket/enclosure measures 71mm L x 42mm W x 25mm H.

Normally marketed as a truck side marker light and only cost NZ$25 retail. (Approx. US$13). Truck marker light? Who cares! I wanted an effective Led light for the overhead interior & nothing else available came close to this one for price & application. The unit is a sealed waterproof item which provides a clean white light that's easy on the orbs, drains very little power, and it provides a good useful spread of light. Once installed as detailed below, the unit is invisible from view from the outside, & does not interfere with the rear view picture. One each of these units has been put into the HT's of our current '94 Sunburst Yellow J-Spec 11, and '90 Mariner Blue Roadsters. I have also put one in the trunk lid in each of our MX5's (boot for the Poms). Having used them for a few months, I now dislike the yellow light provided by the incandescent bulbs and am actively pursuing their replacement with LED's.

On to the mod:

1. Remove hardtop (HT) & relocate to carpeted area. Put a clean cover sheet on the carpet to prevent scratching your paint & invert HT (paint side down).

2. Remove blanking plugs from centre, left rear holes as indicated in previous two pictures. If fitted, remove Defroster cord mounting bracket to expose the hole in the HT skin.
If you do not have the HT with the Defroster panel in the rear window you will have to drill a suitable hole to allow the wiring to come thru. You will discover the HT is made in two shells laminated together forming a hollow walled unit. We're talking factory units here; I have no experience with after market units so the procedure may be a little different to this.

To drill the hole, place a piece of tape over the area on the left hand side as shown above and measure 35mm from the vertical join; measure & mark another point 40mm from the bottom edge of the HT. (This is the factory dimension). Drill a pilot hole of approximately 3mm diameter, followed by a 7mm-drill bit. The tape will prevent the drill bit from skating all over & ruining the finish of the GRP, if you're not careful.

3. Firmly attach a small fishing weight (next picture), to the end of the light braided line & drop the weight into the defroster cable hole. The fishing weight pictured was just a tad too large for this purpose, but it achieved the aim & you get the idea……..

4. Manipulate the HT to drop the weight thru to the first hole where the blanking plugs were removed. Pull out the weight with the tweezers or similar & put aside momentarily, draw a good amount of cord thru. Put a 'bridge' -I used a bamboo skewer- over the hole to keep the light line exposed (so you may retrieve the cords should it not follow the cavity cleanly, jams or gets 'lost' somewhere). Continue dropping the weight to the second (Centre) hole. Pull out the weight & detach it from the light cord. Attach the heavier braided line to the free end of the light line, by TAPE. Knotting it can create a jam between the walls of the HT. Loop the light line around the larger line many times before securing it with tape. You also want to create smooth transition from one cord to another without making a lump that will cause a jam.

5. Carefully draw the heavier braided line thru all the way out. Make sure you have this line exposed out of the second hole also. This heavier line will be used to draw the electrical cable thru the cavity & out the defroster cable hole. Leave the braided cord hanging out of the two holes while you get on with the next phase......

6. Make a spacer plate from alloy that matches the base pattern of your chosen dome light. Drill a hole in the centre of the alloy plate for the wires to come thru. Ensure the hole's edges are radiused or chamfered to prevent chafing a short in the cables that will run thru it.

7. Drill holes; tap threads as required in the spacer plate for the light fitting to mount to. I polished the faces of the plate to a mirror finish for contrast. Screw light to the alloy plate.

8. Attach double-sided foam tape to bottom of the alloy plate. Leave protective tape attached on foam tape for the moment.

9. Attach free end of the lights electric wires to free end of 1/8" braided cord (again, with TAPE) & then GENTLY feed the wires thru the first (Centre hole) as you gently pull the cord from the second hole, taking up the slack. CAUTION: The HT laminate is very thin & if you stress the edges of the holes, it WILL split. Be careful here.

10. When the end of the electric wires is visible at the second hole, remove the 'bridge', & pull the remainder of the loose cord out thru the Defroster cable hole. Continue GENTLY feeding the electric wire past the second hole to the Defroster hole. Pull sufficient cable out thru Defroster hole to allow mounting a plug near to where the current Defroster cable plug is located on the parcel tray.

11. Coil a little cable at the base of the dome light fitting, remove the double sided foam tape protective layer, & place the dome light over the centre hole parallel with the HT window line. The following pictures show the end result just discussed.

13. The coiled cable fits neatly in the recess under the base plate of the light unit and remains hidden from view. It will allow some 'play" should you need to remove it at another time. Attach a plug to the end of the dome light wires. This angle in the roofline allows the Led light to shine directly at the arm rest storage unit.

The finished article is shown below.


14. Run a set of wires from your current interior courtesy lights, under the centre console, carpet to parcel tray and exit beside defroster Plug. Attach appropriate plug on new wires to mate with that of the HT Dome light. So, what do you do with the Defroster cable now that its mounting hole is hijacked by the new dome light wiring? Simple. Make a bracket from light alloy angle as in the photo above & mount it beside the hole with double-sided foam tape. After this photo was taken, the bracket was painted a wrinkle black & installed.

15. You might at this point decide to opt for additional switching to isolate the dome light from the other courtesy lights. Over to you & your taste as required. Replace the HT onto the car. Connect the plugs. Check to make sure everything is working. Go for a drive in the dark.

16. Easy, right?


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24 December, 2005



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