A budget headlight upgrade.

I am working on a project Trident which was purchased in an incomplete state, but also with a few odd parts which had been grafted on during its previous life. The headlight was an ill-fitting later type semi-sealed unit with an odd lamp, but it did not fit the rim at all well.

While a new Lucas headlight unit is readily available for around $90 plus freight, I have never found the original lamp to be particularly wonderful, especially as the bike can cruise happily at 70mph. On my other Trident I once fitted a halogen lamp which was a direct replacement for the original incandescent bulb, but the supply of these seems to have dried up.

Looking around the shed I spotted a box with several sealed beam lamps, also Lucas items, but these had been salvaged from a 1979 Morris Marina which I had scrapped. These lights feature a parklight which clips to the main connector and shines through a small hole in the silvered inner reflector.

As can be seen, this sealed beam is a perfect fit in the chrome rim, and the locator tangs align perfectly. At least Joseph Lucas standardised stuff.!

The wattage of this unit is 50/70, which drags a bit more current from the system, especially on high beam. The bike has it's standard 120 Watt alternator, rectifier and zener diode. Despite this being the electric start model, I have never found the charging system to be inadequate on my original bike in over 40 years use. I did once remove the rectifier to utilise the modern square alloy type, but after no less than 3 failures I refitted the finned job and it still does it's job perfectly.

I have not yet taken advantage of the new LED type lamps, although I think I shall on this bike. Mostly because I have trouble seeing the clocks at night - what with my ageing eyesight and all - so a brighter light in there would help, and with LED's there is no excess heat problem which might otherwise cook the lampholders over time.

I grafted the parklight/connector unit from the same donor source, and once again the Lucas colour code was still correct. Only the earth wires were wrong because the bike is wired positive earth.

Another bonus here.

As you can see, the parklight lamp is a "capless" type which simply pushes into the lampholder. It is just a glass bulb with the two wires folded back along its base which is flattened where it goes into the holder. This bike has always had this type of lampholder inside the instruments, due to being a 1975 model. This means I can use the same LED lamps in all three locations, and it may now be possible to ride in daylight with only the parklight on due to it's serious amount of light output. That would certainly assist faster battery charging while in use.

While I have already fitted the LED's to the instruments, I have not changed this one yet. They come in packs of 2 from Canterbury Auto Electric, so I shall grab some more next time I am (not) passing.

I went to some lengths to make sure the lampholder assembly would fit inside the headlight shell before I made changes to the wiring, and indeed it does, without any contact at all. I did however arrange the wiring to mostly sit around the edges and not in the centre directly behind the lampholder.

I have been testing the wiring as it gets completed and can verify that the insturment lights are significantly brighter. Another bonus is that the LED's are not polarity conscious as I suspected they would be. As LED's are diodes, they will only pass current in one direction. It would seem that the envelope actually houses 2 LED's with one wired in each direction, so you can't go wrong. Very sensible approach considering that the individual components used in manufacture probably cost a few cents each.

The completed article looks exactly as it should, right down to the Lucas trademark in the centre..

No idea how bright it is yet, because there is an issue with the earth wires inside the headlight. Of the three red earths in the original wiring loom, only one is actually connected to earth, so I used that to earth the actual headlight shell so the indicators could be tested. The other two wires are joined to each other but not to earth.! As all three wires run back to a lug that is fitted beneath a cylinder head bolt, I feel that the problem will be there.

Of course - it is the centre head bolt that cannot be removed as it is directly beneath the frame tube. Should have seen that coming..!

However, there are ways around such problems, and I am expecting to enjoy the benefit of a brighter and better focused light, all for the cost of a few solder beads and a good polish up.




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