Twin Headlamps

[cpvh]

Hi All,

Twin headlamps were something to aspire to back in the 70s.

We?re they mostly a pair of main beam and a pair of dipped?

Or were they main/dip in each unit?

[charles]

On my Mk III Cortina it was a pair of main beam & a pair of dipped

[Tim+]

Ditto on my Alfa Sud. Outers were dipped beam and inners main.

Tim

[Dave Plowman (News)]

If Lucas, most common was a twin filament dip, and a single filament main beam. So one pair only on dip, both pairs (with a higher beam from the dip units) on main.

[Harry Bloomfield, Esq.]

[e-mail] used his keyboard to write :

Sealed beam units, one pair had dip, one main. Another car had one pair of combined with a separate pair of mains. Dips were always switched off when mains were on.

My present car is a four headlight xenon job, but the dips remain on with mains.

[Harry Bloomfield, Esq.]

Jim GM4DHJ ... explained on 20/05/2020 :

The twin headlights, or the aspiring?

[Brian Gaff (Sofa)]

Both or either. I'm just trying to remember. We had a consul Classic, but cannot recall the configuration. Brian

[NY]

"Harry Bloomfield"; "Esq." [e-mail]> wrote in message news:ra2lj1$h25$ [e-mail]...

I think when I saw twin-headlight cars in the 70s with their main beams on, all four headlights were lit, so I presume one pair of lights had twin filament dip/main and the other pair had just main. I don't remember seeing cars where one pair of lights went out when the other came on.

I think most of the cars that I've owned in the last 20 years have kept the dipped filament on when the beam is on.

What was the main reason that cars changed from sealed beam to replaceable bulb in fixed reflector? My mum's Renault 6s and my dad's later Citroen GS in the 1970s used bulbs, but his Hillman Hunters and his Ford Sierra used sealed beam. Maybe bulbs started out as a French (or other European) thing, and British cars carried on for longer with sealed beam.

[Chris J Dixon]

You mean that twin filament bulbs are using both simultaneously?

I think the cost of replacement was too high. Also it was a design constraint, you were stuck with a standard shape.

Chris

[Harry Bloomfield, Esq.]

NY laid this down on his screen :

I think happened, when halogen lamps came along.

It began with ordinary bulbs, then along came sealed beams - which improved massively on separate bulbs, then halogen bulbs (brighter, whiter) demanded separate reflectors and lens again. They couldn't make halogen work in a sealed beam unit.

[Harry Bloomfield, Esq.]

Chris J Dixon pretended :

No, not in a combined unit - always one on or the other.

[Dave Plowman (News)]

Which 50s car? Ones which come to mind would be the Rover and Triumph

2000, and larger Fords - all 60s. And they had inferior dipped beam lighting to the more common single 7" units

[Dave Plowman (News)]

To allow halogen bulbs. Although these days you could have a truly sealed beam with a halogen capsule.

[Dave Plowman (News)]

I well remember my first P6 Rover - a Mk1 3500. Standard Lucas 5 3/4 sealed beams. Dips were 37 watt and pathetic. Far worse than a standard Lucas 7" sealed beam.

Changed them to Cibie halogen units which at 55 watt were a big improvment. Had to re-wire, so the dips stayed on with main beam.

Later, twin filament halogen bulbs became available. And with those you could run both filaments at the same time. Arranged them so main beam had all 8 filaments running. Half a kilowatt of light. ;-)

Had a switch so dips were either two or four filaments.

[Jethro_uk]

Not all cars with twin headlamps were sealed beam.

[NY]

Yes. My latest car has H7 twin filament bulb and H7 single filament, in separate housings within the headlamp/sidelight/driving light/indicator cluster. I'm sure the dipped filament remains alight when the high beam is on.

Yes, just checked. There is a difference between headlights on at light switch (when main beam is both dipped and main filament) and headlamps being flashed with light switch off (which is only main beam filament).

But older cars with sealed beams or H4 bulbs seemed to turn the dipped filament off when the main beam was turned on - which meant that *both* filaments (dip and beam) were constantly being switched on and off as each oncoming car approached (dip the headlights) and went past (back to default state of high beam). I wonder if keeping the dipped filament on all the time was done partly to reduce the thermal shock of it being turned on and off all the time, as well as the more obvious advantage of providing a bit more light.

I always wondered why sealed beam lights became so common, given the much higher replacement cost and the much larger object to carry around as a spare. I suppose there was one less variable in getting the headlamp alignment correct, in that filament was always in exactly the same place in relation to the reflector, rather than there being a bit of variation if the bulb wasn't perfectly seated in the reflector housing. I always wonder whether I should get my alignment checked after changing a bulb, because of seating variations between bulb and reflector.

Embarrassing admission. After having my car 12 years, I discovered that it has an extra set of lights for daylight running lights, which were turned off at a menu on the dashboard. These are dimmer-than-dipped filament bulbs in a separate housing, rather than LED: my car is probably just too old for LED technology to be bright enough, so they used filament.

[Jethro_uk]

Hopefully all switched through an appropriately rated relay and fuse ?

[John]

The Alvis TF21 and The Facel Vega had vertical headlights.

[Dave Plowman (News)]

Twin relays, actually. Fed from the main battery cable via fuses. Even a small amount of voltage drop makes a big difference to the light output.

[Jethro_uk]

When the (not road legal :)) 90/100W halogen conversion bulbs became available I rigged up a relay system for my car to fit them.

I also rigged up a relay to disengage the fog light when the ignition was off, since it seemed beyond the wit of manufacturers :)