> Sender units are wound in opposite directions for neg. earth and pos.
> earth cars. The gauges are also made differently as well.
It's possible the sender/gauge change came at the same time as the ground change
on Land Rovers, but the two changes definitely do not coincide for TRs. The TR4
had the later style gauge/sender (which as TeriAnn says, works opposite to the
earlier type); but was still positive ground.
Neither the early nor late styles 'care' about ground polarity, either setup
will work fine on either polarity. The distinction is the type of gauge
movement, "early" gauges are moving vane electro-magnetic, while "later"
original gauges are hot wire thermal (except ammeters which continued to be
moving vane). I believe Smiths continued to make both kinds, but AFAIK
Triumph/Leyland switched over to exclusively thermal gauges using an external
voltage stabilizer as they were cheaper.
Easy to tell the difference with the gauges installed ... moving vane gauges
will snap to the right reading when the key is turned on, while thermal ones
sort of ooze towards the right reading.
Randall
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