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Ammeter gauge replacement

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prb51

prb51

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I'm putting an 80amp alternator in my 56 TR3 and have been advised not to use the original gauge. I'm planning on taking the guts of a more modern unit and using the original guage glass/bezel/face. Recommendations as to the 'modern' donar that would 'fit'(TR6)?
 
Dan Masters of Advance Auto Wire has several solutions for this problem that allow you to use the original gauge. One of them involves a shunt wire where the gauge will read approximately half of the actual amperage is. See page 10 of this pdf from his website. It shows the various options.
 
Gents, Thanks. I checked out the shunt/rewiring of the original and don't like the down side if there is a problem. I think I'll try placing an original face/glass/bezel on a modern unit. I can do that with a non working donar.
 
I replaced my ammeter with a TR6 voltmeter, using the TR 3's curved glass. I am satisfied with its looks, it was very easy to wire, and it works well with my alternator.
 
[ QUOTE ]
Gents, Thanks. I checked out the shunt/rewiring of the original and don't like the down side if there is a problem. I think I'll try placing an original face/glass/bezel on a modern unit. I can do that with a non working donar.

[/ QUOTE ]

Someone correct me if I'm wrong, but from what I got out of reading the pdf from Advance is that the shunt re-wire diverts about half of the current PAST the ammeter, so there shouldn't be any issues with wiring being overloaded if the alternator has a problem. The issues were when you used a 30 amp ammeter WITHOUT a shunt. Then the advice was to go with a 60 amp ammeter.
 
With an alternator you'd be better off with a volt gauge. There are Smiths available but the bezel is different. One can switch the bezel from the amp gauge to the new gauge for cosmetic purposes.
Bob
 
Gents,
In the pdf from Adv.Auto the author mentioned a couple of problems that could arise and the results. Could be I'm being overly cautious.
Bob, which Smiths amp gauge are you refering to (vehicle/ year/model)? What size are the original smith/lucas TR3 gauges (I'm overseas and can't look at my car)?
 
prb51, I'm suggesting that one should replace the amp gauge with a volt guage. A "classic" but new Smiths Volt gauge is available from APT Instruments (www.gaugeguys.com). It is the same size as the stock gauge but the chrome bezel is slightly different. It's not different enough to notice unless one looks closely and compares it to the original gauge. One can, carefully, swith the bezel from the original amp gauge to the new volt gauge if one desires.
Bob
 
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