Message text written by Justin Paxton
>Does anyone have some insight on changing a TR3 from positive ground to
negative ground. Advantages, disadvantages. Someone is recommending it to
me, and I always have an aversion to changing something from stock unless
it
really makes practical sense.
<
The only compelling reason to change is to add modern sound equipment or an
alternator. Some will argue that service personell might try to jumpstart
your car with the wrong polarity (expecting the negative to be earthed) but
the ability to post bold warnings and the rarity of this event makes it a
judgement call. I have left my TR3 positive ground for the same reason I
bought the car: because it si different!
To change it is simple.
1) Disconnect the battery.
2) Reverse the connections to the ammeter
3) Reconnect the battery with the new polarity.
4) (Now to repolarize the residual polarity in the generator) disconnect
the wire from the field connection on the generator, using a jumper wire
momentarily connect this terminal to the positive (now "hot") terminal of
the battery. Reconnect the wire to the generator field terminal.
You have now just changed the polarity of the car.
Note: If you have a "period" radio in the car it must be reconneted or
switched or changed over to negative ground operation.
Dave Massey
57 TR3 (Positive ground)
71 TR6 (Negative ground)
80 TR8 (Negative ground)
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