P100 Headlamp Mounting

Hi Denis,

I don’t think Rob’s P100s are the same as ours. I’ve not seen the structure of the non-dipping reflector of Rob’s type but with a bit of luck it may also be just a question of adding a solenoid and freeing the reflector.


The non-dipping reflector has the mounting tabs attached to it, so it would need quite a bit of modification to be made to pivot.

The chrome bucket has two sets of mounting holes for the reflector, horizontal for the non-dipper or dipping down, and 45 degree for dipping left.

They did not provide anything for dipping right.

Yes, unfortunately that is different from the later P100s where the fixed lamps are just dipping ones with the reflector fixed by a single screw.


I converted my pre war P100s to twin filament

Not as straight forward as one might think. The bulb holders have only a single contact. But I was able to but proprietary bulb holders for twin filament and mix/ match/ modify the various p[arts to co exist and they work very well, The attached pic should explain .but if anyone wants the article email me and I can forward it.

Thanks Peter and Ed, very interesting.
Last week I bought some Lucas catalogue CDs on ebay from somebody in Surrey calling himself classic-car-manuals, so when they come I’ll see what they have to say about variations and developments in the P100 lights.

I also tried this many years ago and found it impossible to obtain focus on both beams. One or the other but never both. That said, I have the post war diffused glasses rather than the proper fluted pre-war ones.


Below is the type of double filament bulb that I used (unmodified example top left). Perhaps bulbs with a different filament positioning might work better than my hopeless one. The arrows point to the two filaments.

The Lucas CDs arrived today, from Simon Mckenzie of Epsom.
Here’s a shot of the first page of the 400B 1939.

The “Dip and Switch” reflector in the left hand lamp has the solenoid that moves the reflector, and also performs the disconnection of the right hand lamp by some contact points in there.

Looks like the price of a dipping reflector for a P100 in those days was 30 shillings.
Interesting that the P80 pair is offered with two dipping or one dipping, and dipping vertical is standard, unless left dipping is specified. Perhaps that was for continental Europe?

Those headlights just look sooooo… right!

Why all the restoration effort/drama Rob,

See, you can buy new ones at only GBP20 5s each, so only about USD60 for a pair, plus postage!

Yeah, I could probably find 20 pounds and 5 shillings in 1938 issued currency at a coin dealer, but it might cost me $1000.
And where could I find a Time Turner to go back to then? They all got destroyed in Harry Potter book 5. Hmm, what happens in fiction when you go back to a time before you were born? Do you become a negative person? :laughing:

I think w’d need to consult Marty McFly.


I quite often see dipping solenoids on ebay UK

You need to check whether 6 or 12 volt.

Hi Rob,
The picture you show from your catalogue is of a P100L, which is what is fitted to the post-war Mark IVs, but was introduced by Lucas in 1939. You can see that they are hinged at the bottom, so open downwards making it much easier to change bulbs, etc. My car was fitted with these when I bought it, with the fluted glass as shown, whereas post-war they had fluted glass.

Your car has the earlier type, P100R or P100S, which have the hinge at the top and a completely different design for the reflector.

Interestingly, the P80 in the picture still has the hinge at the top.

Thanks Denis, I hadn’t noticed that. As you say, it is a pain having to hold up the lens with your head just to change a bulb and especially to install the reflector, fitting 3 wrapped wires through that spherical washer and connecting them, dropping little screws and hoping they don’t fall down in the trough under the grille.

I’ll keep an eye on ebayuk, though as yet I haven’t seen any need to dip my lights when oncoming cars are blasting me with their LEDs and long range driving lights in town.

Don’t know that I’d put much faith in Marty McFly as a car guy, what with putting whitewalls and then railcar wheels on a Delorean. :laughing:

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A bit pricey…

Dipping solenoids

I always find that looking at ‘completed items’ gives a better indication of prices as opposed to wishfull thinking. So I found that two NOS solenoids sold for gbp 20 in Nov. six volt but a better indication.

That seller would probably do better if he showed the part numbers. They all seem to be missing the roller end.
I’d also need the dipping reflector with pivot frame.
Or leave it as is; I see so many cars running around here with only one headlight.