At 17:20 28.03.97 -0500, you wrote:
>Fellow Listers:
>
>Has anyone on this list converted a TR2, TR3, or TR4 from positive ground to
>negative ground?
>
>I have been looking into this, and have arrived at some conclusions, but I
>would like help from someone who has "been there, done that".
>
>As I see it, the following changes will need to be made:
>
>1) replace the generator/control box with an alternator
>
>2) reverse the ammeter leads
>
>3) swap the ignition coil, or reverse the leads
>
>4) swap the battery leads
>
>5) reverse the leads to the interior heater
>
>6) change the starter
>
>As far as I can see, nothing else needs to be done, based on the following
>rationale:
>
>a) lights, turn signals, and horns are not polarity sensitive (I have
>actually tested horns).
>
>b) The windshield wiper motor converts rotary motion to linear motion, so the
>direction of rotation is of no concern.
>
>c) the voltage regulator for the gauges, and the turn signal flasher are
>bi-metal strip/thermal devices, so they are not polarity sensitive.
>
>d) the fuel and water temperature gauges are, I think, bi-metal strip/thermal
>devices, so polarity is of no concern.
>
>e) relays are insensitive to polarity.
>
>Can anyone shed some light on this, correcting me where I am off base? I am
>particularly interested in the gauges, and the starter swap, but all input
>will be very much appreciated.
>
>Thanks in advance for your help!
>
>Dan Masters,
>Alcoa, TN
>
>
Hi Dan,
nothing has to be done but:
- swap the battery leads
- swap the ignition coil leads
- start your engine!
The ammeter will point to the wrong direction, which is cosmetic in my eyes.
And the rest of the electric devices will work properly as before. They are
all non polarity sensitive!
Exception: The radio (if fitted)
Any electronic devices (if fitted)
The reason why things work is that they either react on a magnetic, non
polarized basis (regulator, signal flasher ..) or on a ohm resistive basis.
The motors should be turning in the same direction if do not have permanent
magnetic exitation. But as far as I know TR3 through TR4A they do not have.
If a motor has a coil in the stator for magnetic exitation (starter motor
has) this will reverse its polarity as well as the rotor will. Which makes
the whole thing turn in the same direction as before.
You may have some difficulties in exciting the dynamo for the first time
(but really only the first time) so that charging will not start. If so, you
must polarize (great word!) the dynamo once by closing and opening again the
contacts of the voltage coil in the regulator. You see the dynamo trying to
rotate!
I have done it twice successfully! Godd luck!!
Rainer Wallnig, TR4 63 dayly
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