TR6 Ammeter Gauge query

[jojim65]

Hi,

 

Quick question on Ammeter Gauges please,

 

The Lucas one fitted to my 1970 car is marked +/- 30amps and can, on starting go to full deflection and stay there till I tap the glass. I assume therefore that the gauge is not original.

 

I understand an original gauge for my car would not have the number, just C+ & -D.

Would that still be rated at 30amps or would it be greater i.e 50 or 60amps.

 

And, if I were to change out the ammeter and replace with a voltmeter, which gauge would be best suited for a CP TR6.

 

Thanks

 

Jim

[barkerwilliams]

Jim,

 

My 70 has a similar ammeter which is original. I sent mine to JDO who changed the shunt in the ammeter and although it still reads 30-0-30 it will handle 60 amps without wrapping the needle arond the stop.

 

I believe many cars have the issue after fitting larger capacity alternators. Yes you can fit a voltmeter, there is a Smiths quadrant faced voltmeter available for under £40 but the car would also need a little adjustment to the heavy powercables from starter to alternator, via the ammeter with a spur off the the ignition switch. Those cables were rated as sufficient for the original car setup without rad fans etc. and lower ouput alternators so they may need replacement and re-routing. Cable is not expensive but is time consuming to fit. The whole job including gauge would probably cost £60 but might take half a day of installing to get a neat result. Dash might need to be removed for access unless you are very bendy!

 

 

Alan

[MostEasterlySteve]

All the available repro gauges do not match the original CP instruments. I fitted a used voltmeter the other day to my CP - I'll post a picture if I can work out how! It is the ONLY voltmeter Smiths ever made that more or less matches.

 

I understand all ammeters fitted to cars with alternators should have 60 amp ammeters.

[MostEasterlySteve]

[RogerH]

Hi Alan,

in theory and generally in practice the only current going through the ammeter is the charging current for the battery.

Any increase in alternator size should make no difference to the charging current.

 

The 30 amp gauge should be OK.

 

Roger

[Denis]

I had my Alternator with uprated diodes years ago, the original Lucas Amp meter C+ -D works normally in my 69 CP car.

[jojim65]

Thanks for your replies gents, very useful and I do like the alternative voltmeter, I understand it comes form an Jaguar XK which may make it pretty rare!

 

Jim

[MostEasterlySteve]

Yes, late E-Types but also possibly late 60's saloons such as 420G. I paid £40 on eBay and spent ages cleaning it up. Luckily the dial printing survived my efforts with cotton buds soaked in 3-in-1 oil.

[stuart]

Thanks for your replies gents, very useful and I do like the alternative voltmeter, I understand it comes form an Jaguar XK which may make it pretty rare!

 

Jim

Doubt its from an XK as they would have an ammeter.

Stuart.

[Dave I O W]

battery meter.jpg

 

 

 

Hi Steve I have the same volt guage as you but I disguised it a bit

 

Cheers

 

Dave.

[MostEasterlySteve]

Oh my word, so you did. I had to study it before the penny dropped!