The Resurrection of TA0844 (Part 7)

This is the last article in the series and I must thank Bob Butson for the time and effort that he has spent in writing for the magazine. I know that his articles have been very helpful to TA owners as well as being interesting to readers. This article contains some notes about TA electrics and we start with a spreadsheet which shows the power requirement for TA lighting in original rig and the same after modern bulbs (including halogen headlights) are fitted.

Click Spreadsheet for Bigger View

This spreadsheet was compiled by Ian Linton based on modifications for his TA. The power requirements far exceed those available. One can fit a TD dynamo rated at 19 amps as Ian has, or reduce the load by using LED bulbs in all locations except the headlamps. This latter modification will still result in some current drain from the battery. Ian obtained his halogen headlamp bulbs from

Setting up a G45NV D21 TA dynamo, which is rated at eleven amps (132 watts), to give this current continually, will result in overheating and possible failure. Brian Rainbow is reliably informed that the current should be limited to 9 amps for safe continuous operation, giving 108 watts.

The arrangement of the PLC2 switching and the two field resistors in the CJR3 cut-out alters the charging rate for various switch positions. In the LOW position both resistors are in circuit. In the HEAD position the resistors are switched out to give maximum output. I have heard that it was favoured to include an additional ten ohm resistor in series with the field circuit in the LOW position to reduce the battery charge. Overcharging causes ‘gassing’ in the battery and lowers the electrolyte level. I would be interested to know if anyone has tried this, and the outcome.

For all lamps, I have fitted an earth connection, taken to a chassis earth. The lack of these, relying on mechanical contact, which may be painted or rusty, is what gave the ‘Prince of Darkness’ his name. The cloth covered loom which I purchased some time ago does not have an earth provision for any lamp.


I used a 15D double contact holder inside a Lucas 1132 sidelight with an LED cluster which has a white section and an amber section. The bulb is No. LD1NDOW1BAY15D, this can be found at

Together with the rear lights (including the auxiliary rear lights) the current taken is 0.68 amps.

Rear / brakelamps

To have a single ‘porkpie’ lamp one side of the number plate is now illegal. It was powered by two15S parallel pin 6w bulbs, one for rear/number plate and one for a brake light. I have fitted a lamp each end of the number plate, an original ST38 and a later version (or reproduction) which had three 15S 10w bulbs. The reproduction lamp I had was obtained at an autojumble many years ago but the bulb contacts were loose and could not be tightened. My solution was to make a copy of the ST38 innards, achieved by sifting through my bin of plastics parts and cannibalising the repro lamp innards for the bullet connector sockets. The ST38 was fitted with an earth connection whereas the repro lamp relied on the mechanical connection of its securing screws. Paul Goff of makes an LED board insert for the ST38 which may be more suitable. I obtained a number of 15S bulbs, each with a cluster of 9 LEDs, very cheaply via eBay. These bulbs are brighter than the 10w tungsten bulbs.

Also I have installed a ‘high level’ brake light on a bracket secured to the top of the spare wheel carrier to show through the spokes. This is a 24 LED strip also obtained via eBay which takes 0.225 amps.

One lamp each side of the number plate may be legal but they appear to be mounted too low to be observed by some vehicles following close behind. For this reason I made an auxiliary lighting bar.

This design was chosen because I did not want to drill holes in the car body or in the Paul Ireland luggage rack. I made bracket hooks from 1.2mm stainless steel which support a 10mm square section tube, one metre long with the lamp mounts at the ends made from 1mm steel left from body skinning. The hooks fit under the luggage rack pivot bolts. A small six-way connector enables the bar to be removed with ease. The extra LED stop/tail bulbs and the indicator bulbs were purchased some time ago via eBay and the aluminium square section tube from B&Q. The Lucas lamps were found at autojumble.

The three photos above show Bob’s auxiliary lighting set up.
‘High level’ brake light and fixing bracket for positioning behind the top half of the spare wheel so that it shines through the spokes – a sensible safety mod these days!

Above: Reproduction ST38 obtained at an autojumble but with loose bulb contacts. Below: same light but now fitted with different innards as described in the text by Bob.
Photos show Paul Ireland’s luggage rack (mentioned in the text and shown earlier in one of the photos showing Bob’s auxiliary lighting set up) before fitting and fitted and folded down ready to accept luggage.


As mentioned in the June issue I have dispensed with the solenoid dip reflector for the nearside headlamp using the plain left reflector and another for the nearside from Keith Ardley. Tel 01353 778493. I used double filament halogen 35/35 BA15D bulbs coded B1235BA15QH from Paul Goff.

When setting up the double filament bulbs in the reflectors the bulb filament should be at the focal point for the main beam. In front of this point a dark spot will be observed in the middle of the beam, behind this a divergent beam is very broad and scattered. This can be set up as follows:

Mount the reflector in a piece of board which has horizontal and vertical markings, in an orientation as located in the headlamp shell. Mount the board in a bench vice at one end of the garage using a spirit level to check that the board is set correctly horizontally and vertically. Insert the bulb, lightly clamp and connect the main beam filament to 12 volts. Move the bulb in and out of the reflector until the correct spot is observed at the other end of the garage, disconnect the main beam and connect to dip. Rotate the bulb to orientate the dip pattern and clamp the bulb in the reflector. Repeat these moves to check alignment. The reflector is now ready to install into the headlamp shell for further horizontal alignment when fitted to the car.

The fog lamp will be fitted with a 35watt halogen bulb.

Dash lamps

These were covered in TTT 2 Issue 11. They take 0.32 amps.

For this all LED operation, the current required will be 0.32 amps for dash lights, 0.68 amps for sidelights and rear lights, 0.47 amps for brake lights and 0.47 for indicators (per side). The indicators can be ‘on’ both sides to give a hazard warning. Also required are 5.85 amps for headlamps and an additional five amps approximately for coil and pump. Total for night- time fine weather running is 12.32 amps.

The ‘S’ and ‘H’ fuses in the cut-out need downsizing. For the S (rear, brake and side) total current is 1.8 amps, and the H 5.83amps. Suitable fuses would be 5 and 8 amps respectively, old style examples can still be found at autojumble.

I hope the battery charger still works.

Bob Butson

Ed’s note: Full details of Paul Ireland’s luggage rack were given in TTT 2 Issue 2. Paul can be contacted by e-mail octagon(at) (substitute @ for at) or by telephone (44) 1206 298736.

Ed’s further note: Brian Rainbow, having helped me proof read Bob’s article, has flagged a couple of points to watch: Bob mentions that Ian Linton has fitted a TD dynamo to his TA giving more output. If you do this, please bear in mind that the TD has a 2 brush dynamo and requires a regulator, therefore you must replace the TA Lucas CJR3 cut-out with a suitable cut-out/regulator like an RF95 or similar, plus a link wire on the PLC2 ignition switch so that High and Low operate the same. Bob makes a very wise choice of LED bulbs in his TA. LED bulbs are polarity sensitive, and most proprietary LED bulbs are for negative earth. The TA is positive earth as standard, so you must buy positive earth LED bulbs, or convert the car to negative earth which is a fairly simple conversion.

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