18.3 - Jaguar Diseases ( George Haynes,
One characteristic of switches that most people are not aware of
is that they require a certain amount of current to work properly.
Under normal circumstances a certain amount of oxidation will build
up on the switch contacts which has the effect of insulating the
contacts from each other.
Packing the switch with dielectric grease and designing the
contacts so they wipe each other helps solve the problem, as
does wetting the contacts with mercury. However, none of these
design techniques are present in the SU fuel pump. It needs to
rely on current flow to burn through the oxide layer.
If you put a transistor in the circuit you eliminate the current
flow through the points so they don't burn and wear out but this
creates the aforementioned second problem instead.
The points in the SU fuel pump are perfectly capable of handling
the 3 Amps that the pump draws, but they get burned by the high
voltage arc that is generated when the points open (just like an
The solution is simply to install a suitably sized (3 Amp) diode
across the coil. Such diodes are available from Radio Shack as part
numbers 276-1141 through 276-1144. Diodes are polarity sensitive,
so connect the diode lead that is marked with a band to the coil
terminal that connects to the positive side of the battery. Forget
the transistor and just use the points to carry the current.
There's no need for the capacitor if you have the diode.
In spite of the fact that I love to add electronic devices to our cars,
this is the best solution for this application.
18.3.1 - More Jaguar Diseases ( Pater Havas,
After reading your column on Jaguar Diseases, I felt compelled to share the results of my own research in this area with your readers. While the field is certainly broad,a nd there is no lack of subjects to study, I feel it is imperative to classify the various afflictions, infections, syndromes, and behavioural traits before new models come out and corrupt my research. Below are a few of my most recent findings. I welcome all comments from like minded field researchers.
Spontaneous Part Regeneration SPR:
The innate ability of any Jaguar part, when dismantled from the car after failure
and replacement, to "heal" itself and be suitable for service again if left in a closed dark place for long enough, or immediately upon the part no longer being available either rebuilt of NOS from any source.
A) Immaculate diaphragm healing.
B) Spring height re-establishment.
C) Piston Ovality suddenly acceptable
D) The inclusion of the phrase "Close enough" in your vocabulary.
E) A .22 feeler gauge appears thin.
F) Sand blasted Pot metal parts look almost as good as new
G) The sure and certain hope that "Maybe THIS time it won't break" becomes dogma.
H) A loss of memory for exactly how many miles the part already had on it, but the conviction that it "wasn't much".
This affliction usually occurs early in the restoration, in what Psychological experts have come to call the "Collection" phase. It is typified by the patient scouring auto-jumbles, and junk yards for ANY period parts and / or accessories. Said material is then acquired, and although it has no use whatever in the restoration of the car at hand, is trotted out at the merest suggestion of the drop of a hat with the wry comment that "You've never seen one of these." or "I know lots of people who would kill to have some of these.". After appropriate billing and cooing over the object(s), the patients status has risen immensely, and the material is then re-shelved to await the next victim. There is no known cure. Early stages of this affliction are characterized by people commenting that they 've " .got two of those back home in the barn." when shown a particularly desirable piece at an auto-jumble.
The developed ability to instantly tell which nuts and bolts on a Jaguar are metric, which are not, and which wrenches can be cross-referenced to round the shoulders of both. Often mis-diagnosed as Hexasnapophobia, or fear of reading wrench sizes and frequently confused with rank stupidity, the afflicted person can often be heard mumbling: " I don't get it. It worked on MY car"
Dismissed by some as a myth, researchers are increasingly convinced of the existence of this strange phenomenon, which to date apparently is prevalent only with British made Automotive paraphernalia. Symptoms include a close attention to detail when re-building a particular part with the factory approved kit, and complete instructions.
The most severe evidence is with Lucas Generators , S.U. and Stromberg Carburettors. When correctly assembled and installed with precision, the part will have so bonded with it's maker, that it will steadfastly refuse to function on it's own, and "Just want to be taken apart again". There can, therefore, be no substitute for slap-dash assembly.
Double Optipupilotomytosis, or "Bush Babies Syndrome":
A condition caused by driving Jaguars at night, relying on Lucas to show you where your dash-board is. The victim's pupils often expand to ten times their normal size, requiring them sometimes to wear sun-glasses at night when arriving at their destination. Sufferers often prefer the company of their own, to avoid the possibility of being suddenly blinded by lighted cigarettes, flash cameras or inadvertently stepping in front of a BMW.
A painful and embarrassing physical condition, caused by Jaguar drivers cocking their heads back, while leaning forward, to actually see the end of the front wing when pulling out of a parking space. Sufferers are frequently confused with erudite snobs, due to the "Nose in the air" stance they assume in public. The experienced Jaguar driver, however, will instantly recognize this for the debilitating condition that it is, and take pity on the afflicted.
A syndrome shared with Sail-boat owners. The disease is typified by an inability to remember anything about past Jaguar ownership, except through a rose-colored fog.
The conviction that normal physical laws do not apply to common consumable parts on Jaguars.
They wear out due to:
C) Somebody else's incompetence
The inability to recognize that common consumable parts on Jaguars do not wear out due to:
C) Someone else's incompetence