TECHNICAL TIPS - ELECTRICS

SUMMER CIRCUIT: Got charging problems on the Summer circuit?  Just remove the cut-out assembly; drill off the back cover, exposing two coils; either one or both will have disintegrated.  Either replace with 2-ohm wire or shorten and re-fit.  Problem solved!!
STARTER SWITCHES: I have twice had starter switches (Ruby type) catch fire because dirt trapped inside them combined with oil (the starter is just below the filler cap) has caused an internal short circuit in the switch. Check yours by flicking the switch lever backwards and forwards and sideways to see if it sparks. To rectify any problems dismantle and clean.
SUMMER HALF CHARGE: If the summer ‘half charge’ switch doesn’t seem to work, look around for two resister coils—2 coils of wire about 1.5“ long and 0.5“ dia. connected together at each end.  They will either be on top of the dynamo with a fuse or as part of the cut-out on the bulk head.  Sometimes, a bodge has been perpetrated by connecting the two terminals on the dynamo with a piece of metal.
A 12v REGULATOR is readily available from a Morris Oxford or Austin Cambridge and the following changes have to be made: a 12v battery, all bulbs to 12v, new 12v coil and a 20-30 ohm resistor for the fuel gauge. In addition, I have found that Cibie lamp units from a Renault 4 give excellent lighting whilst looking better than the reverse taper rims needed to fit Lucas 700 units.
CHECKING THE POLARITY: To check the polarity of an A7 - Most Austin Sevens were originally negative earth but I have come across some that aren’t—perhaps they were changed over in the 60s when many ‘modern’ cars became positive earth to help prevent rusting (it was thought). To save doing any damage to your dynamo, or reversing its polarity by mistake, replace the battery with the normal negative going to earth, i.e. the body of the car, do not start the engine but switch on the headlights and look to see if the ammeter is showing a discharge. If it is showing a charge, then the cables are the wrong way round. However, the terminal posts on most batteries should be different sizes as should the connectors so you should also be able to tell when you try to refit the terminals to the battery.
BATTERY ISOLATOR SWITCH: Austin Sevens have always been prone to catching fire. The main cause is the lethal mixture of oil and sparks which can occur together around the starter motor terminal. Oil can drip from the filler tube directly down onto the electrical terminal below and, should the securing nut become loose and a spark develop or the insulation becomes oil-soaked, the hot oil quickly ignites. On a less dramatic point, I have always been happier when putting Baby to bed, to know that everything electrical is disconnected and there is no danger of a nightmare developing unseen. The answer: to fit an isolator master switch in the main power lead from the battery. There are two sorts – a simple turn-key affair or the more sophisticated ‘Dis-Car-Net’ battery terminal extension, both available in all high street motor shops. For the Box, I chose the simple turn-key as the battery is underneath the driver’s seat and to operate the terminal switch would entail lifting the seat and the battery cover every time. The turn-key was fitted in the front panel of the driver’s seat mounting box and can be operated by simply reaching down and turning the key. Later cars with the battery under the bonnet can have the turn-key fitted through the bulkhead in line with the driver’s right knee picking up the main battery lead on its way down to the starter motor. The only tool I needed that might not be in everyone’s kit was a 2” metal hole-cutter but I saw one in In Excess the other day for £1:50! One final advantage, of course: switching off and taking the key with you is an excellent anti-theft device.
STARTER MOTOR FIRES: It might be wise to warn people again with starters under the bonnet to keep the switch clean and free from oil, being especially careful when topping up the engine oil as the switch is directly under the filler tube. Another good reason to install a battery master switch (See above tip) - Gary Munn
CUT-OUT POINTS: Recently, the ammeter started to show that disturbing symptom of a very fluctuating charge which took some time to cut in. I did all the usual stuff - checking/cleaning the brushes, cleaning the armature and cut-out points—absolutely no difference! Then I looked more closely at the cut-out gap - it didn’t look too wide but in the usual spirit of ‘try anything’ I closed them up a tad and, lo and behold, a steady immediate full charge! But one word of warning: don’t close them so much that they don’t open - otherwise you’ll end up with a flat battery and perhaps worse! Here a battery isolating switch is a valuable safeguard! Ian Mason-Smith
CHANGING HEADLAMP BULBS: The headlamps fitted to 1932 Austin Seven saloon cars have special double-filament Lucas/Graves bulbs ; the main filament provides the normal driving beam, and the secondary filament, which is slightly in front of the main and is surrounded underneath by a shield, provides the deflected anti-dazzle beam on operating the switch on the steering column. On these lamps the securing screw cannot be swung clear of the slotted plate at the base of the lamp, as is usual when releasing the lamp front, and any attempt at forcing this screw clear will only result in the reflector being dented from the inside. For removing these lamp fronts, it is necessary, after slackening the screw, carefully to prise off the front with a suitable tool and then, by swinging the top of the lamp front forward and downward, lift the slotted plate clear of the screw. Alternatively, the screw can be re-moved entirely, but if this is done, it must be ensured that the anchoring plate is not pushed away inside the lamp body, as this will necessitate dismounting the reflector before it can be reached. The correct Lucas-Graves bulbs can be obtained from any Austin dealer or Lucas Service Depot. From The Austin Magazine.
REPAIRING BULBS: How about this tip from "Workshop Wrinkles and Recipes" edited by Percival Marshall in 1935. Repairing filament lamps - shake the bulb whilst the current is on - the broken ends of the filament will touch and weld together. This has got to be the ultimate in money saving tips for the Seven owner. Bumbling, A7OC Magazine (A7OC)
DIPPING HEADLIGHTS: We have received a communication from Messrs. Joseph Lucas, Ltd., to the effect that, in the case of cars fitted with Lucas Dip and Switch Headlights, the lights should never be switched off while the reflector is in the "dip" position. This is because, as described in the last issue of the journal, the reflector is held in the dipped position by means of a solenoid. When the current is switched off, the solenoid ceases to function, and the reflector springs back into the normal position. When the lights are again switched on, the solenoid comes into action immediately and dips the reflector. The filaments in the bulbs, when either cooling off, or getting warm, are exceedingly brittle, and the jar caused by the dipping or releasing of the reflector, when the bulbs are in this condition, has a great tendency to shatter the filament and render the bulb useless. Austin Service Journal July1930

EMERGENCY REPLACEMENT DYNAMO BRUSH-SPRING:  Take a good chunk of ordinary car-washing sponge – yes those big yellow jobs – just tear off a sizeable bit and jam it firmly between the dynamo casing and the brush-holder. Hey presto! a brand new brush-spring (probably cleans the commutator as well). Result – a great charge of 10amps, good enough even to hold the Chummy headlights! Ian Mason-Smith

Whilst removing your BATTERY WINTER STORAGE it is a good time to inspect the battery box for any signs of corrosion, clean off any rust and treat with special acid resistant paint available from good motoring accessory shops. When reinstalling the battery after the winter ensure that you treat the battery terminals with petroleum jelly (Vaseline) to prevent future corrosion. Incidentally the corrosion (blue stuff) which may be present on your cable terminations can be removed very effectively by removing them from the cable and then running them under hot water. Bumbling (A7OC with many thanks)
RUBY HEADLIGHT RIMS: Did you know that the original Lucas headlights on a Ruby have a second inner metal silvered ring around the inside of the glass lens which the “w” shaped springs bear on to hold the glass in place? This has got a cork gasket between it and the glass which forms a seal to protect the silvering on the reflector from water. Some people have been known to assemble the lights with these items missing.  “Bumbling”  A7OC with many thanks.
LED STOP LIGHT: Cornwall Club member Steve Baldwin has attached an LED high-level stop light to the rear end of his Box. It is screwed firmly through the spare wheel cover and wired-in to the normal stop lights below. However, there is one proviso—they will only work for 12 volt conversions, of course. They can be bought from SVC for £25 Contact Tel: 01827-67714 or ordered on-line at www.s-v-c.co.uk/product/small-led-high-level-brake/Steve Baldwin CA7C

LED LIGHTS: Ron Hayhurst recently fitted LED lights to his Box Saloon - with splendid results. He bought them from Classic Dynamo and Regulator Conversions.  See www.dynamoregulatorconversions.com where they show various options. From the BA7C newsletter with many thanks.

LED INDICATOR BULBS: A precautionary note regarding the fitting of the LED indicator bulb replacements. LEDs take much less current than filament bulbs so the contact surfaces within the trafficator arm need to be cleaned up to a bright metal finish as they need the full 6 Volts at the bulb in order for them to flash.  Thanks to AutoBumbler, A7OC.
BATTERY SPECIFIC GRAVITY: The amount of charge a battery requires is naturally determined a by the calls on its current. To verify if your battery is being overcharged remove each cell cap while the engine is running at a speed sufficient for the dynamo to operate, and then observe if the electrolyte is in a state of slight effervescence and giving off bubbles of gas. Use an electric torch if a light is necessary for this examination, as the gas might ignite or explode if a naked light is used. As the density of the electrolyte varies directly with the state of charge, the condition of the battery can be more positively determined with the aid of a hydrometer, an instrument for measuring the specific gravity of the electrolyte, which can be purchased for a few shillings from any garage. The specific gravity of the electrolyte when the battery is fully charged should be about 1.28 to 1.300 as indicated by the immersion of the hydrometer float in the electrolyte, drawn into the hydrometer. When fully discharged the hydrometer will indicate a specific gravity of about 1.115. It should be remembered, however, that these readings are subject to the electrolyte mixture being correct. If the level. of the electrolyte has not been topped up to. its proper level with distilled water (i.e. up to. the tops of the separators) its specific gravity will be high, giving, an optimistic indication of the state of-charge. On the other hand, if at any time the acid has been spilled and replaced with distilled water, the electrolyte will, be weak, and a correspondingly low specific gravity reading will be given. When gassing through over-charging takes place, topping up will be more frequently required, and acid fumes may pass out of the vents and attack surrounding objects. Usually these are not serious effects and overcharging is not so harmful as the effects of persistent lack of charge, but you should be able to judge to what extent the "Full Charge" switch position should be employed to keep the battery in good condition without undue over-charging.  From the Austin Magazine Feb 1936
HORN NOT WORKING?  If you release the carburettor control leaver tube from the bottom of the steering column you will be able to raise the lever and unfasten the horn button. The horn button is comprised of two parts, the portion you press and the body immediately under it. Grip the lower portion with a thin pair of pliers and it will unscrew, then you can pull up the broken wire and solder the original nipple to it. Or replace the whole wire if it is fractured somewhere.  Practical Motorist
TOP UP THE BATTERY: Have you noticed that your A7 dynamo is constantly charging your battery at about 8 amps unlike a modern car where the charge rate depends on how full of charge the battery is?  So where does all this energy go? – it boils-off the water in your battery, that’s where.  Modern batteries can be ‘sealed for life’ because when they are fully charged, the alternator cuts off whereas in our Babies, the charge keeps coming and the battery water gets lower.  So make it a regular job before every run to check the battery water level at the same time as the tyres, oil and water to save ruining the battery.  David Whetton
A precautionary note regarding the fitting of the LED indicator bulb replacements. LEDs take much less current than filament bulbs so the contact surfaces within the trafficator arm need to be cleaned up to a bright metal finish as they need the full 6 Volts at the bulb in order for them to flash.  Thanks to AutoBumbler, A7OC.

ELECTRICAL STARTER CIRCUIT TESTING
1. When testing your starting circuit for voltage drop you must remember you are looking for a potential difference throughout the circuit.
2. You will need a volt meter.
3. Check the potential difference between the two terminals of the battery, fully charged you should expect up to 6.6 volts (2.2 volts per cell, anything over 6 volts will be good enough.
4. Engage the starter and the voltage should not fall below 5 volts.
5. If using an analogue meter, switch it to the lowest setting, usually 1 volt.
6. Next check the potential difference between the positive battery terminal and the starter terminal with the starter engaged. If there is more than ½ volt you will need to narrow down where the potential difference is.
a. Check between the terminal post and the terminal on the battery lead, then the lead itself.
b. Between the terminal post and the next joint which could be a battery disconnect switch across the terminals.
c. The starter button on bacon slicer starters.
d. If any of these have a potential difference of more than ½ volt you will need to remove it and determine why.
e. Next go through the same exercise on the earth side of the battery, earthing the system can be the cause in many cases but the potential difference will always show where the problem exists.
f. If there is no joint that is responsible for the potential difference but there is ½ a volt or more, make sure the cross section of the lead is not too small as this can be a cause.
Reproduced from The Austin Seven Club of Western Australia thanks