TR2/3/3A Adding a Voltmeter to a TR3?

[karls59tr]

I'd like to replace the Ammeter in my TR3A with a Voltmeter but I'm still running positive ground.Will this be an issue? Are there any period correct voltmeters out there?

 

[TFB]

I am also going with voltmeter for my TR3 with alternator conversion.The 2" hole size limits selection,with most american gauges 2 1/16,and I didnt want to alter dash.
Moss has the Smiths@$80,but I ordered this one from UK ebay.About $40 bucks after shipping.Looks like a nice built gauge,with light.
Next task is to try and fit domed lense.
Battery orientation to car is irrelevant,just wire gauge correctly..
voltmeter
Tom

 

[Geo Hahn]

I think I understand why a voltmeter is preferable for a car with an alternator but not clear on why it is more desirable than an ammeter on a car with a generator/dynamo.

I can, course, check voltages as part of usual diagnostics but for a gauge that warns me of trouble it seems like an ammeter would be better.

 

[TR3driver]

Just personal preference, IMO. I like the ammeter better even with an alternator. Both Stags have voltmeters, and they border on useless IMO. An ammeter tells you what is happening right now, this instant, while a voltmeter only tells you what happened in the past. I think the main problem is that most people don't like knowing that their generator (or alternator) isn't keeping up at idle, or with the turn signals, etc. But just the other day, my ammeter told me that my brake light switch was bad, something you will never learn from a voltmeter.

As Tom says, most automotive voltmeters don't care about polarity. The exception would be the modern electronic ones. But IMO he is mistaken about "american" gauges, they fit just fine. Here's a cheap Sunpro temp gauge from my FLAPS installed in my TR3 dash (since replaced with a Smiths gauge from a TR4)

 

[TFB]

Hey Randall,I guess some do fit.
I only went by listed sizes for my search and most seemed to be listed 2 1/16.
My dash hole is 2.030,so I assumed 2 1/16 wouldnt fit.
I am going to voltmeter mainly for ease of wiring.
I like that Altimeter look of of the Sunpro.
BTW I also have the Smiths temp tr4 electric gauge,with flat glass.Wondering if I can put domed glass on it.
Tom

 

[TR3driver]

I don't know if the curved glass will fit the later gauges, but it seems likely. I just started with an early TR4 gauge, which already had curved glass and looks nearly identical to the TR3 gauge (except for reading to 250F). IIRC the flat glass gauges had a shroud over the needle that makes them look different.

Don't forget, you'll also need the voltage stabilizer. I found a non-working mechanical one in the junk bin, and installed a solid state 10v regulator inside it.

 

[JFS]

The curved lens from a TR3 will fit a TR6 voltmeter. I used this combination on my TR3 when I converted to an alternator and seems to fit right in with the TR3 gauges. The car is not easily accessible for a pic right now.

 

[CJD]

Gee Randall...you monitoring a car engine or a nuclear reactor? That's a lot of temp!



LOL John

 

[TR3driver]

It's just what I found on the shelf at my FLAPS. Only about $20 as I recall, and it fit both the dash and the thermostat housing with no modifications. The only extra step was to run power to the internal light (making it the only gauge easily legible at night )

Yeah, it reads pretty high, but some engines can get that hot when they are boiling over. I've had it over past the 250 mark, running just a 10 psi cap & 50/50 glycol. Limped home after the water pump pulley parted ways with the pump.