Vintage Headlight Dipping

[Peter Adams]

The headlights on my 1926 Rolls-Royce 20hp have single filament bulbs,
and the method of reducing the glare for oncoming drivers is by
operating a dashboard mounted switch that reduces the current and dims
the bulbs. I presume this is legal, because the car passes its MOT every
year.

In the course of tracing an intermittent fault, I found that the near-
side headlamp is still fitted with a solenoid and a movable reflector.
This indicates that the dipping mechanism was originally of the type
where the off-side headlamp is extinguished and the near-side reflector
swivels towards the kerb.

In principle, I would like to restore the original mechanism, but have a
vague recollection that the system became illegal - which presumably
accounts for it being modified to a dimmer. I seem to remember talk that
oncoming traffic might not notice the off-side sidelight, and think the
single headlight belonged to a motorcycle.

I know that a 1970s amendment stipulated that cars first registered
after 1 January 1931 are required to have:

'Either two headlamps that are capable of double dipping, or two groups
of headlamps so arranged that the outside lamps can emit dipped beams
and all other lamps emit main beams'.

But can anyone who has a better memory and/or detailed knowledge of
vehicle lighting regulations, advise me whether my car's original
system, or indeed the present dimming system, are legal for a car first
registered on 25 June 1926?

Peter
(Remove 'spam' to e-mail)

[Geoff Mackenzie]

Post by Peter Adams
The headlights on my 1926 Rolls-Royce 20hp have single filament bulbs,
and the method of reducing the glare for oncoming drivers is by
operating a dashboard mounted switch that reduces the current and dims
the bulbs. I presume this is legal, because the car passes its MOT every
year.
In the course of tracing an intermittent fault, I found that the near-
side headlamp is still fitted with a solenoid and a movable reflector.
This indicates that the dipping mechanism was originally of the type
where the off-side headlamp is extinguished and the near-side reflector
swivels towards the kerb.
In principle, I would like to restore the original mechanism, but have a
vague recollection that the system became illegal - which presumably
accounts for it being modified to a dimmer. I seem to remember talk that
oncoming traffic might not notice the off-side sidelight, and think the
single headlight belonged to a motorcycle.
I know that a 1970s amendment stipulated that cars first registered
'Either two headlamps that are capable of double dipping, or two groups
of headlamps so arranged that the outside lamps can emit dipped beams
and all other lamps emit main beams'.
But can anyone who has a better memory and/or detailed knowledge of
vehicle lighting regulations, advise me whether my car's original
system, or indeed the present dimming system, are legal for a car first
registered on 25 June 1926?
Peter
(Remove 'spam' to e-mail)

Peter - please don't take this as definitive, but my memory of the
Construction and Use regs broadly says that you may use whatever was
originally fitted provided it works. So you could not use single dipping
and swivel on a more modern car, but if that's the way it was originally
built then I think you should be OK. Your car may have been "upgraded" in
the thirties, as many were to take in later coachwork, semaphore indicators
etc, but that does not disqualify original equipment. Probably the RREC
would be able to give more useful advice.

Geoff MacK

[Dave Plowman]

Post by Peter Adams
But can anyone who has a better memory and/or detailed knowledge of
vehicle lighting regulations, advise me whether my car's original
system, or indeed the present dimming system, are legal for a car first
registered on 25 June 1926?

I can just about remember the legislation for two rear lights coming into
operation. We had a Morris Minor which had to have an extra lamp fitted,
although there was already a dummy there. One of the few bits of
retrospective construction and use type regulations. And I *think* the
requirement for two dipped headlights came in at the same time, although
IIRC all post war cars - and many pre - had a double dipping system. I've
seen some pre-war cars fitted with two solenoid operated dips - presumably
using discarded parts from another.

Not sure if it applied to cars of all ages, but the twin tail lights
certainly did.

I'd have thought there would be a much more sanitary way to provide dips
on your car - although perhaps you don't use it on unlit roads?

[gaspode]

Post by Peter Adams
The headlights on my 1926 Rolls-Royce 20hp have single filament bulbs,
and the method of reducing the glare for oncoming drivers is by
operating a dashboard mounted switch that reduces the current and dims
the bulbs. I presume this is legal, because the car passes its MOT every
year.
In the course of tracing an intermittent fault, I found that the near-
side headlamp is still fitted with a solenoid and a movable reflector.
This indicates that the dipping mechanism was originally of the type
where the off-side headlamp is extinguished and the near-side reflector
swivels towards the kerb.
In principle, I would like to restore the original mechanism, but have a
vague recollection that the system became illegal - which presumably
accounts for it being modified to a dimmer. I seem to remember talk that
oncoming traffic might not notice the off-side sidelight, and think the
single headlight belonged to a motorcycle.
I know that a 1970s amendment stipulated that cars first registered
'Either two headlamps that are capable of double dipping, or two groups
of headlamps so arranged that the outside lamps can emit dipped beams
and all other lamps emit main beams'.
But can anyone who has a better memory and/or detailed knowledge of
vehicle lighting regulations, advise me whether my car's original
system, or indeed the present dimming system, are legal for a car first
registered on 25 June 1926?
Peter
(Remove 'spam' to e-mail)
--
Peter Adams,
Lincolnshire, England

Peter

I am in the midst of a restoration of a car with the same system and it just
so happens that I spoke to my friendly local MOT examiner only last week on
the subject. His opinion (which my car club confirms as correct) is that the
system is perfectly legal. Apparently it was outlawed sometime in the
sixties or seventies but became reinstated as a result of further
legislation sometime in the eighties. You are therefore free to reinstate
the single dip system should you wish. I would personally advise against it
however if you intend to use the car during the hours of darkness - it just
isn't safe in this day and age. There are plenty of other solutions which
usually involve fitting new bulbholders and double filament bulbs. This
however will involve running extra wiring for a dip switch (the switch
fitted will not be a changeover switch) an additional wire to the nearside
headlight for the dip filament and a wire to the dash for the obligatory
blue main beam warning light.

Gaspode

[Adrian]

and a wire to the dash for the obligatory blue main beam
warning light.

There's absolutely no requirement for a dash mounted main-beam warning
light, and even if there's one fitted, it doesn't have to be blue.

I've got umpteen cars with no indicator or beam warning light, never had
even the slightest comment off the tester. On one of the few in the "fleet"
that does have a beam warning light, it's orange.

[awm]

Post by Adrian

and a wire to the dash for the obligatory blue main beam
warning light.

There's absolutely no requirement for a dash mounted main-beam warning
light, and even if there's one fitted, it doesn't have to be blue.

Yes there is a requirement but it isn't part of the normal MOT test
procedure to check it.

[AWM]

Post by awm

Post by Adrian

and a wire to the dash for the obligatory blue main beam warning light.

There's absolutely no requirement for a dash mounted main-beam warning
light, and even if there's one fitted, it doesn't have to be blue.

Yes there is a requirement but it isn't part of the normal MOT test
procedure to check it.

Can you find any reference to back that up?

MOT test covers all obligatory lights - main beam and flasher tell tails
are obligatory but they are not part of the test procedure nor are thery
listed on the VT29 check list.
A similar problem existed over numberplate lights which went out and in as
an MOT failure item -- they are very firmly a failure if not working.

[Adrian]

Post by awm

Post by Adrian
There's absolutely no requirement for a dash mounted main-beam
warning light, and even if there's one fitted, it doesn't have to
be blue.

Yes there is a requirement but it isn't part of the normal MOT test
procedure to check it.

Can you find any reference to back that up?

MOT test covers all obligatory lights - main beam and flasher tell
tails are obligatory but they are not part of the test procedure nor are
they listed on the VT29 check list.

"They're obligatory. All obligatory lights are tested. But they aren't
tested."

To me, that sounds more than a little contradictory.

The MOT book, as on www.motuk.co.uk, specifically states that an *audible*
indicator tell-tale is acceptible. There is NO mention of a beam tell-tale.

Now, I've not got access to the "genuine" MOT tester's manual, so it may be
that that site is incorrect in it's transcription.

OK - let's ignore the MOT. That's not *everything* wrt legality.

If indicator and beam warning lights were obligatory, they would be fitted
to all new cars available in the UK, would they not? And, up until the
demise of the 2cv in '90, they were not fitted to 2cvs for UK spec. For
other countries, where they *were* undeniably required, they were fitted.
For those countries, fog lights often weren't required, so weren't fitted.
DimDip was a UK only thing, so was only fitted to UK cars. Therefore, if
indicator and beam warning lights were required here, they'd have been
fitted.

I'm perfectly willing to be proved wrong, so if you have any evidence other
than a gut feeling, please do prove me wrong.

[Ian Johnston]

On Wed, 1 Oct 2003 08:24:33 UTC, awm <***@nohere.com> wrote:

: Yes there is a requirement but it isn't part of the normal MOT test
: procedure to check it.

I have a car built in 1985 which doesn't have one.

Ian


--

[awm]

Post by gaspode
Peter
I am in the midst of a restoration of a car with the same system and it just
so happens that I spoke to my friendly local MOT examiner only last week on
the subject. His opinion (which my car club confirms as correct) is that the
system is perfectly legal. Apparently it was outlawed sometime in the
sixties or seventies but became reinstated as a result of further
legislation sometime in the eighties.

The regs were change to accomodate Citreons with headlights that turn
when front wheels are steered. Don't think this aplied to dipping
mechanisms.

Post by gaspode
You are therefore free to reinstate
the single dip system should you wish. I would personally advise against it
however if you intend to use the car during the hours of darkness - it just
isn't safe in this day and age. There are plenty of other solutions which
usually involve fitting new bulbholders and double filament bulbs. This
however will involve running extra wiring for a dip switch (the switch
fitted will not be a changeover switch) an additional wire to the nearside
headlight for the dip filament and a wire to the dash for the obligatory
blue main beam warning light.
Gaspode

I think "The Complete Automobilist" might be able to supply all the
required parts.

[Malcolm]

There is a problem in trying to solve the problem by just fitting twin
filament bulbs. These rely on there being a prismatic glass on the
headlamp. As most solenoid dip lamps have either only a plain or frosted
glass switching between filaments does not "dip" the beam it just makes it
slightly out of focus. My MOT man has never seemed to mind however. Most
old lamps are so dim that dazzle is rarely a problem

Quite a few cars in the 1920's had a dimming rather than dipping arrangement
that switched the two headlamps from parallel to series

Malcolm

[Peter Adams]

In article <bli3rh$ejd$***@titan.btinternet.com>, Malcolm <***@remove
thisbtinternet.com> writes

Post by Malcolm
There is a problem in trying to solve the problem by just fitting twin
filament bulbs. These rely on there being a prismatic glass on the
headlamp. As most solenoid dip lamps have either only a plain or frosted
glass switching between filaments does not "dip" the beam it just makes it
slightly out of focus. My MOT man has never seemed to mind however. Most
old lamps are so dim that dazzle is rarely a problem
Quite a few cars in the 1920's had a dimming rather than dipping arrangement
that switched the two headlamps from parallel to series
Malcolm

Yes Malcolm, my headlamps are fitted with plain glass. Thank you for
telling me that the dimmer switches between parallel and series, it will
help me diagnose the intermittent fault, as I had thought it might
involve a resistance.

I am most grateful to everyone who took the trouble to respond to my
post. It seems my friendly MOT tester is right when he describes vintage
car headlamp legality as 'a grey area'.

Conversion to double filament bulbs would be the completely legal and
safe course, but also the most complicated, and I don't envisage driving
the car at night except in a dire emergency.

Restoring the original extinguish/swivel system would be satisfying, but
with Geoff and Gaspode saying it's legal, and 'awm' saying it definitely
isn't, it appears a bit controversial.

On the whole, I think I had better stay with the dimmer system that has
passed MOTs for umpteen years.

This solution is what my late father called: 'Pursuing a masterly policy
of complete inactivity'.

Peter
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[awm]

Post by Peter Adams
The headlights on my 1926 Rolls-Royce 20hp have single filament bulbs,
and the method of reducing the glare for oncoming drivers is by
operating a dashboard mounted switch that reduces the current and dims
the bulbs. I presume this is legal, because the car passes its MOT every
year.
In the course of tracing an intermittent fault, I found that the near-
side headlamp is still fitted with a solenoid and a movable reflector.
This indicates that the dipping mechanism was originally of the type
where the off-side headlamp is extinguished and the near-side reflector
swivels towards the kerb.
In principle, I would like to restore the original mechanism, but have a
vague recollection that the system became illegal - which presumably
accounts for it being modified to a dimmer. I seem to remember talk that
oncoming traffic might not notice the off-side sidelight, and think the
single headlight belonged to a motorcycle.
I know that a 1970s amendment stipulated that cars first registered
'Either two headlamps that are capable of double dipping, or two groups
of headlamps so arranged that the outside lamps can emit dipped beams
and all other lamps emit main beams'.
But can anyone who has a better memory and/or detailed knowledge of
vehicle lighting regulations, advise me whether my car's original
system, or indeed the present dimming system, are legal for a car first
registered on 25 June 1926?
Peter
(Remove 'spam' to e-mail)

The original system is illegal, the current system depends on the the
head lights being set below the "dazzle angle" for its legality.