Recently the list had a thread about TR4A grounding and the use of alternators
vs. generators. I have found some info on the grounding aspect of that
thread. Based on what I have several conclusions are reasonable.
I have a Service Memo dated April 26, 1965. This memo, from the Triumph
Distributor in Union NJ to all dealers, discusses Negative grounding and
states that:
"In the interest of standardization, most vehicles manufactured in England
will, in future, change over to a negative ground system."
The purpose of the memo was to give a "heads up" to dealers to alert them that
negative grounding was coming and they should prepare for it.
Based on that date and other comments in the memo I conclude that:
1) All TR2/3 and TR4's were manufactured with positive ground electrical
systems
2) Early TR4A's were also positve ground
Now, that means that sometime after that memo (and I would not imagine that it
occurred for at least 6 months or more) TR4A's were converted to negative
ground. Since the first TR4A (Jan'65) was CTC50006 and the first TR4A in '66
was CTC 64148, I figure that all TR4A's from CTC 50006 to CTC 60xxx were
likely positve ground. (That is based on an extrapolation that CTC60xxx was
built in the fall of '65.) It could be that the 4A's continued to be positve
ground for longer but that I can't deduce from what I have.
Nothing on alternators except Piggott's comment that they were an option on
TR4A's. So far, no-one on the list has one as original equipment. Cheers.
Art Kelly '64 TR4 CT33118L (original owner - UK delivery/US specs)
Vintage Triumph Register (VTR) TR4 vehicle consultant
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