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| Austin Seven LED headlamps correctly adjusted. The feint horizontal line above the pool of light is the centreline of the headlamps. |
Upgrading lights and fitting
LED bulbs
In the last issue
I told the story which led me to decide to fit LED bulbs to my 1932 Austin
Seven.
LED (light emitting diode) bulbs have
been around for a while now, for both cars and most other applications, but
only comparatively recently have they found their way into older vehicles. Considerably brighter lights for minimal current consumption make them ideal for vehicles
with charging systems and lamps designed for a by-gone age.
The
principles of fitting them are the same for any classic or vintage car: first
decide if your existing lamps are suitable for LED upgrading and then select
the correct bulb for the job. LEDs are available for any lamp, vintage or
classic, although some modification may be required. Read on!
If your lamps are unsuitable, for whatever reason, you may have to obtain some appropriate replacements and fit them to the car.
If your lamps are unsuitable, for whatever reason, you may have to obtain some appropriate replacements and fit them to the car.
It isn’t hard
to install these bulbs, although a degree of confidence and competence in
fiddling with electrical components may be required in some cases. Head and
side lamps are pretty straightforward, although it is essential to beware of
the dazzle issue I warned about in the last issue. If you do experience this, repositioning the LED within the lamp, moving
the bulb holder to correct the focus and so on, may correct it.
To illustrate what may be involved in
upgrading your own vintage or classic car to LEDs, I thought it may be helpful
to describe in some detail what was involved for my 1932 Austin Seven.
In this case the side lamp and dipping headlamp bulbs fitted
straight in with no modification and, if you are fortunate, the latter will be of the
pre-focus type which do not cause dazzle.
More thought
is needed for the rear lamps, depending on what is currently fitted and what
outcome you wish to achieve. The original Austin Seven tail lamps are of the
one-inch ‘fag end’ variety often seen on vintage motorcycles. These are next to useless,
especially as only one of them was fitted by the factory. Since I was going to the trouble and expense
of doing this work, my plan included going the whole hog and upgrading to new tail
lamps incorporating stop, tail and flasher to make me safer on modern roads.
I wanted to
achieve this whilst keeping the appearance of the car in period as far as
possible. To me there is nothing worse than seeing a vintage car equipped with lights
screwed on in odd places that are obviously trailer or motorcycle in origin instead
of correct-period lamps.
I achieved this by fitting Lucas LD 109 side lamps
on the front wings to act as flashers, with orange LED bulbs but retaining the
clear glass lenses so as to ’look proper’. Originally there were no indicators
at all fitted to these cars (except the driver’s right arm!). At the rear I adapted
a pair of Lucas ST38 ‘pork pie’ lamps with new split red/amber lenses.
The ST 38
rear lamp was original equipment on Austin Sevens a year after mine, and the LD
109 type of side lamps were fitted to Ruby models a couple of years later, so
to most people they look original. Both original secondhand lamps and new
reproductions are readily available on the internet and at autojumbles.
In most
cases the LEDs have bayonet caps identical to the bulbs they replace, so they
are simply ‘plug and play’. However, it is necessary to ensure you have the
correct type for your lamp as LEDs are not bulbs in the old-fashioned sense but
are directional (only shining in one direction) rather than glass globes that
emit light all around.
Comparison between conventional and LED bulbs (right).
The bayonet caps are the same but the LED light source ends are very different,
depending on the application.
Also, for
reasons I cannot explain, in certain cases the LED must emit the colour
required by the particular lamp – amber for flashers, red for tail lamps etc,
even if they are fitted behind lenses that are the appropriate amber or red.
The ST38
rear lamps have to be fitted with ‘light boards’ instead of regular LED bulbs. This
is also true for the Lucas ST51 D-lamps that were a popular fitment on
immediate post-war cars, as well as the Lucas 471 angular wing-mounted lamp and the more-rounded 549 that were standard on many 50s/60s cars including Morris Minors and
some Jaguars. Although it may be
possible to modify these lamps to accept a regular bayonet-capped LED, the result
would be a single point of light behind the lens, due to the directional nature
of LEDs, whereas the light boards literally fill the lenses with bright light.
Light boards
look similar to printed circuit boards. They have a number of LEDs on them
which shine different colours to perform the three different light functions,
plus white for the number plate illumination. They come with full instructions and the
necessary fitting kit, but do require removal of the old bulb holders, new
holes to be drilled and some form of connections to be devised.
Additionally
I had to provide a period switch, a flasher unit and the necessary wiring for
the flashing indicators. It is essential
to use a flasher unit designed for use with LED bulbs, which are both
obtainable from the same supplier.
Finally, I
added a warning buzzer to let me know when the indicators are working. I can think of few more self-inflicted
dangerous situations than approaching a junction with a forgotten indicator flashing
merrily away even though you intend to carry straight on. Who can blame anyone who pulls out in front
of you? And with the famous Austin Seven
brakes, there ain’t much you can do about it!
So far, so
good. Road testing the car on the first
dark night revealed that I now had bright white headlamps and really visible
rear lamps and flashers. And, best of all, the ammeter showed a healthy charge
all the time. No more flat batteries for
me!
An Explosive Experience
My little
Austin Seven gets used a lot. My cars aren’t
show queens and are out and about come rain or shine. As well as trundling off
to the pub and shops, the car is driven on many of my local Austin Seven Club
runs. These comprise thoughtfully-reconnoitred country lane routes planned to
suit 90 year old cars with 747 cc engines varying between 13 and a heady 17 bhp. There are even three evening runs in the
summer, ideal for those cars with decent lights which enable their crews to
linger in the pub afterwards and not have to scamper off before the gloaming.
After a
short while we began to notice something strange. We found that we returned
from a nice fast run (in Austin Seven parlance that means a steady 40 mph) with
stinging eyes and a catch in the throat. The cause was not at all clear at first – although,
with a little thought, it should have been obvious.
My first
idea was oil dripping onto the exhaust pipe.
But no, it wasn’t that. Then I
reckoned I had tumbled to the answer: a
few weeks earlier I had fitted a 4-blade fan in an attempt to cool the engine
better and overcome the stultifying effects of modern fuels. My idea was that the engine breather (three
small holes in the valve cover) was emitting by-pass fumes that were now being
forced inside the car through the many un-pluggable holes in the bulkhead and
floor by the supercharged air from the 4-blade fan.
“Easy”,
thought I, “I shall fit a by-pass pipe to the engine breather so the fumes are
emitted into the slipstream down at chassis level.”
To this end, eBay produced a modified valve cover that had the 3 breather holes plugged and a take-off connector fitted instead, probably for an oil catch tank for an Austin Seven racing car. (Yes, they do exist, and very popular they are too in the 750 and Bert Hadley formulae!) I made a natty pipe from copper pipe and Bob was my uncle.
To this end, eBay produced a modified valve cover that had the 3 breather holes plugged and a take-off connector fitted instead, probably for an oil catch tank for an Austin Seven racing car. (Yes, they do exist, and very popular they are too in the 750 and Bert Hadley formulae!) I made a natty pipe from copper pipe and Bob was my uncle.
But,
unfortunately, he wasn’t.
Much head
scratching and several unpleasant drives later, I mentioned this to other
Austin Seven owners and one of them said that he had experienced something
similar. He had gone down the same emissions by-pass route before he realised
the true cause of the problem: the battery was being overcharged. Couple this
to the fact that the battery is under the passenger seat and it became obvious
that what we both suffered from was breathing in the hydrogen gas produced by
the overcharging.
Yes, the interior
of the car had been filling up with the same hydrogen gas that burned with such
tragic consequences when the R101 airship crashed in 1930!
Clearly, one totally unexpected by-product (by
me, at any rate) of fitting LED bulbs to my Austin Seven was that the minimal current
draw together with the lack of any current regulation, apart from the rather
coarse 3rd brush adjustment and the summer/winter charge settings, meant
that even the weedy Austin Seven dynamo could overcharge its 6 volt battery
with aplomb.
The healthy
charge shown by the ammeter after fitting my LED bulbs that I had thought was a
reason for celebration was, actually, quite the reverse!
Added to
this, I keep the car connected to one of those smart battery conditioners when
it is resting in the garage, thus ensuring that the battery is top notch even after
a period of inactivity. But the dynamo still cheerfully pumps out its 4 or 8
amps so the battery starts gassing freely the moment I set off down the road.
What should
I do about this unhealthy state of affairs? Yes, OK, I could put the tungsten bulbs back
in, but that would be rather defeatist.
I attempted to adjust the 3rd brush to give a lower output but couldn't reach a suitable compromise for high and low charge. Even in the low charge setting the high charge output was, well, still too high.
One solution
initially appeared to have my dynamo converted into 6v 2-brush machine coupled
to an electronic regulator/cut out, but then I discovered that there would be a
significant cost as it’s likely the field coils would have to be rewound to
give them adequate resistance for the 2-brush conversion. Alternatively I could also change to an
alternator (sorry!) with its inherent advantage of built-in regulation, but
that is also pricey and has a far higher output than I need. However, on the
plus side, both of these would be visually indistinguishable from standard.
The Solution
Rather than
splashing out large amounts of money, surely there had to be a cheaper
way? What was necessary was a method of
limiting the dynamo output to prevent the battery being overcharged.
I put my
thinking cap on, and again I raised the matter with other Austin Seven owners.
One particularly helpful fellow pointed out that if I substituted the
half-charge resistance with one of a greater value, the charge rate could be
reduced to the minimum required by the ignition circuit with the switch in the
summer position. The 3rd brush could be adjusted to give a suitable
output from the dynamo in the winter setting.
This seemed
so straightforward that I decided to give it a go.
How big a
resistance? Well, it seemed it would be largely a matter of trial and error. I
started by measuring the ohms value of the original resistance coil. This seems
to vary from car to car, and on mine it measured 1 ohm. I tried several resistors of different values
and settled on a 2 ohm 5 watt ceramic wire wound type that fits neatly into
the box on top of the dynamo in place of the original resistance coil.
I then
adjusted the 3rd brush to give 4 amps output in the winter setting. Most of
the time I drive with the switch in the summer position in which the ammeter
now shows just barely 1 amp – the important thing is that the battery is not
being discharged but holding its own. Should it be necessary - such as after a lot of uses of the starter motor or a dickey battery - one can simply switch to the winter (high charge) setting.
One other thing. The light switch has two positions: first it turns on the side lamps (inside the headlamp reflectors) and secondly the headlamps themselves. When the headlamps come on, the high charge rate automatically kicks in. When this happens, the ammeter reads 1 amp as all the LED bulbs combined use just 3 amps.
So, all round a win-win situation. And the cost? Just £1 for the resistor! Best of all, the gassing problem seems to be cured and I have the peace of mind of decent lights all round.
One other thing. The light switch has two positions: first it turns on the side lamps (inside the headlamp reflectors) and secondly the headlamps themselves. When the headlamps come on, the high charge rate automatically kicks in. When this happens, the ammeter reads 1 amp as all the LED bulbs combined use just 3 amps.
So, all round a win-win situation. And the cost? Just £1 for the resistor! Best of all, the gassing problem seems to be cured and I have the peace of mind of decent lights all round.
Plus, all of this is completely reversible with zero impact on the car except for holes for the front (flasher) sidelamps.
I shall
trial this for a few months with a voltmeter temporarily connected to the
battery so I can monitor its state of health. I’ll report back with the results
in a future issue. Stand by!
A wirewound ceramic resistor of the
type fitted in this modification. This
is a 6.8 ohm one, too great a value for this application but has the same dimensions as the one used.
Also shown is an English pound coin to indicate the size as well as the
cost!
NOT JUST
AUSTIN SEVENS
As most cars
built up to the mid-1930s used 3rd brush dynamos, the problem I
experienced will certainly apply to them if they fit LED bulbs. However, it may not be so obvious for several
reasons. For example, the battery may not
be inside the car, or it may be an open model that is predominantly driven with
the hood down.
These cars
may not gas their occupants but will certainly suffer from batteries which
require frequent topping up or which expire suddenly from lack of electrolyte.
It would be well worthwhile investigating if a simple modification of the type I have
made to my Austin Seven would benefit these cars before investing in more
expensive solutions.
Of course,
there are many classic cars, particularly postwar, which have 2-brush and
regulator charging systems. These can be
fitted with LEDs without difficulty as the regulator takes care of the charge
rate. For example, I have fitted LEDs to my 1947 MG TC which has dramatically improved the lights without any
further modification.
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| Austin Seven LED tail and stop lamps. |
In the next issue of Vintage and
Classic Car Gazette:
·
How
I bought a 1947 MG TC at auction and discovered the meaning of Caveat
Emptor!
·
Tracing
a car’s history – a few tips now that the DVLA has withdrawn our right to know
who the previous owners were.
