pre-pre-focus bulbs

[volker.halbach]

I have still the original setup in my headlight with 6V and the original pre-war socket. For years I used an old Lucas bulb, but then changed for an LED:

The light was much brighter than that of the old bulb, but I haven't been able to focus the LED correctly. After a few hundred miles the LED bulb stopped working. I found another cheap new conventional bulb (see picture), which lasted less than 100mls. I now put in the old Lucas bulb and haven't had any problems. But I would like to have a spare, and LED wouldn't be bad. I have an electronic regulator and don't think voltage varies wildly. Does anyone have recommendations for another LED bulb that lasts?

I also don't understand the focusing problem, because the light source sits more or less in the same position relative to the reflector.

[Roger Gwynn]

When using a pre-pre focus bulb, as the name suggests, you need to focus it by sliding it backwards and forwards, the original holder has the ability to do this. I have one LED bulb fail on me, the vibes shook it apart, normally they are very reliable.

[volker.halbach]

Thanks, Roger. Maybe I was just unlucky with that bulb. Girder forks are not kind to the headlight.

I can focus the headlight by sliding the bulb holder back and forth. It works perfectly with a conventional light bulb and I get a well-directed beam, but not with the LED, perhaps because the light source is more concentrated in one place with the conventional light bulb.

[Roger Gwynn]

The best but more expensive bulbs are from https://www.dynamoregulatorconversions.com I think it was one of his that fell apart on my bike, I now have a cheap one. Warning the website is not very easy to use or understand!

[volker.halbach]

Thanks again. Their LEDs have a built-in lens, which should solve he focusing problem. But they are £42,00 each (incl. VAT and shipping)!

[simon.holyfield]

Thanks again. Their LEDs have a built-in lens, which should solve he focusing problem. But they are £42,00 each (incl. VAT and shipping)!

They certainly work pretty well. Best beam pattern I've found, and of course you don't have to worry about the state of the reflector.

[ralfpenkert]

Voler, Simes
re: reliability
in two machines, one VH500, one german Horex the older led version is still working. Since 4 years or so.
re focus:
they work good to make you seen at daytime, but forget them at night.
Half of the beam shows a bit up half a bit down, but never both centered.
Reason is the led position itself.
The new ones are much brighter and there is a lens in front, but result is more or less the same.
And Simes: don't forget the headlights glas, its a kind of a distributor.

Ralf

[simon.holyfield]

I'm using the ones with the lens - older ones are nowhere near as good. The one I have used most is in the WNG, which has the original flat diffuser glass so perhaps this doesn't disrupt the beam pattern as much as later lenses.

[volker.halbach]

Thank you, Simon and Ralf. I did some more research. I found the LEDs with lens also here: https://www.classiccarleds.co.uk/ I'll give them a try, hoping that their LED won't fail my like the previous when I went home in the evening. There are also different, much cheaper LEDs with lens on ebay from China; but cheap LEDs in the car didn't last long.