The Restoration of PRRROWL
TIGER # B382000221
An Article by John Crawley
February, 2001
Page 12
ELECTRICS BY LUCAS
"TIGER, TIGER shinning bright, TIGER, TIGER with things that NEVER NEVER Light" .... or something like that.
I finally got all the electricals working on the TIGER. If there are three words to caution you about Lucas electrics I would say they are: Ground, Ground, Ground. One poor ground in the system can do some strange things. A poor ground on a signal light, for example, can feed current back through the system and power something not even remotely connected (so you think) to the signal lights.
When you try to trace a poorly working light start with two long wires hooked to a low amperage battery charger or the positive and negative terminals of the battery. Watch it — these can short out and get HOT quick. With these plus a test light you can start to trace problems quickly. First connect the positive to the center of the offending light then connect the ground wire to the side. This will tell if the bulb works or not. Next put the bulb in the holder and repeat by attaching the positive wire to the pigtail of the holder and the negative to the body of the light fixture. This will tell if the receptacle is O.K. Next try powering it with the positive only to the pigtail to see if the ground to the car works. If all is well go to the first junction in the harness and try applying power there. You can use the test light to work your way along the wire testing for power as you go. Each component except the instruments can be tested in this manner. If you have strange problems such as dimly glowing bulbs or test light check every ground again. Never assume anything. On my TIGER I chased electrical problems for three days. I finally discovered that a Tail light assembly was not grounded. The stud that is riveted to the light assembly, to hold it to the car, was loose. This normally is riveted to the body of the assembly and is the attaching point for the ground wire. The stud had been removed for re-chroming and then replaced resulting in a poor contact between the stud and the fixture body. When the rear lights were turned on they could not find ground on one side. The electricity, in seeking ground, fed back through the signal lights and powered that whole part of the system. As you can see strange things happened. Persistence will pay off in checking electrical gremlins. When trouble shooting suspect ground problems first. Then look for fixture problems. Shorts will be obvious because they will blow fuses or will result in the smoke being released from inside the wires. Remember there may be more than one of each type of problem in a circuit. Make sure that there is a ground strap on the engine.
TIP:
- Check battery ground by attaching a test light to the ground terminal and the alligator clip to bare metal. Have someone start the car. If the test light glows battery ground is not adequate.
- Try again between the engine and bare metal on the frame. If the test light glows the engine ground is not adequate.
I interviewed a chap who was in charge of Lucas experimental division during the 1960s. I started the interview by asking him why Lucas had such quality problems. His reply: "Did they?!!! I was not aware of that."
He told me some interesting stories of his time at Lucas including how they decided that tire technology would never get any better and that they could market roads that had treads cut into them. The theory was that it did not matter if the tread was on the tire or on the road so they spent gobs of money experimenting with different treaded road surfaces.
(Ed. Note: They actually did saw fine (1/8 - 3/16 inch) longitudinal grooves into the California freeway concrete with multiple diamond saw bladed machine. Supposed to provide better traction in the rain. Sure made the surface more wavy in the driving direction, probably due to uneven wear with exposed edges, and variable cut depth along the road.)
He also related how his laboratory was on the top floor of the Luca plant and his entrance was up a rickety fire escape. One day one as he was going up the fire escape to start work when one of the last few remaining bolts in the wall broke. He decided that it was too dangerous to continue and instead went around the building and used the main entrance. Mr. Lucas stopped him and asked why he was using the customer entrance. When he explained that the fire escape was too dangerous to use Mr. Lucas said: "I never asked you about safety I asked you why are you using the customer entrance."
We have had the fellow as a guest speaker at one of our All British Field Meets and have enjoyed enough stories to know that there if he could be persuaded to write his of experiences at Lucas it would make a great book.
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