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Has any one messed around with the instruments, specifically the volt meter? I noticed the other day that this gauge on my Series 3 didn't register anything when I started the car, and for the short drive to the shop. Then it started to move, jerky, and finally got to the 13V mark. I have a spare, installed it and it did the same thing. I had not noticed it before.
I opened the spare and applied 12v and found that the plastic needle is a bit bent and is dragging on the face, causing the start-stop motion. The one in the car appears to be the same. Is that supposed to be the case?
I was able to slightly bend the spare to clear the face and it seems to be fine, but why would both needles be bent in the same manner?
The gauge doesn't operate like a normal voltmeter, I think there must be a resistance element that heats and moves the needle via a bi-metallic element, hence the slow motion, but certainly a more stable reading.
seems like the needles warp with aging. The voltmeter in my '84 is also very slow to register
If I tap on the glass it moves quickly to where it needs to be. Again, I think it is caused by aging.
Every Series III I've owned, seen, or worked on....quite a few in all....has a lazy voltmeter.
A long time ago (twenty years?) somebody who knows about these things opened up the four aux gauges and discovered how/why they are different from the norm. I can't remember the details, though. I'll try to find that info. And when the change was made from Smtihs to Veglia instruments the unusual design apparently was kept.
On top of that is the bent needle thing, itself a bit of a mystery, which adds to the problem.
Hmmm. After I straightened the needle a bit on the spare, it is still slow to respond, but does so smoothly. Tapping does move the needle along before straightening. I'll go with bent with age, especially if there is a heating element in there.
I think I'll put the now smooth functioning spare device in the car and work on the original. Pretty easy to open, remove the rubber ring, then a very small roll on the bezel over the housing flange that can be moved without damage. I didn't have to upset it for more than 1/3 of the diameter before I could work it out. It went back in pretty easy as well, then I rolled the bezel back over the flange with a round rod rather than trying to crimp it.
Excerpt from an old J-L posting which explains the difference between Series I-II gauges (using an external damper/regulator) and Series III gauges (Internally dampened)
"The Series 3 gauges are a different type of gauge, having two coils, one of which compensates for the varying system voltage. Obviously you don’t want or need that in the voltmeter, so it just has one coil which pulls the needle across dependant on the voltage applied to it. There is also a ‘‘damper’’ on the needle which prevents rapid fluctuation, and therein lies the answer to why the gauges are slower to react....."
Interesting note on the gauge operation. I'm not sure how the damper works because on can easily move the needle by hand without any resistance. But in any case it works.
Project complete. I love projects that can be completed on these old cars in one sitting. The replacement gauge is installed and functions as it apparently should, slow but purposeful. Original is removed, opened, needle bent to clear the face, closed up and back on the shelf for another day. I did notice that the original needle appears to be broken off, about 2mm shorter than the replacement. Both gauges are Veglia.
Thanks for the comments and assistance.
Clarke - I bought one of those first but rejected it because it wouldn't stay powered in my cigar lighter socket. I always had to wiggle it to get it to read. That's why I elected to do away altogether with the OEM socket and go with something with a direct connect. And, again, the USB charger built in was a real bonus for keeping my phone charged as I use WAZE alot for my GPS navigation.
Lid closed, but still reveals voltage Lif open to gain access to USB port and on/off switch.
Clarke - I bought one of those first but rejected it because it wouldn't stay powered in my cigar lighter socket. I always had to wiggle it to get it to read. That's why I elected to do away altogether with the OEM socket and go with something with a direct connect. And, again, the USB charger built in was a real bonus for keeping my phone charged as I use WAZE alot for my GPS navigation.
Lid closed, but still reveals voltage Lif open to gain access to USB port and on/off switch.
Thanks for to heads up Bill, I will see how it goes. Once it is in I shouldn’t need to move it.
I have a triple USB socket hard wired on the shelf under the steering column with my gps and mp3 permanently plugged in and just turn them on at the unit when needed. Third socket is for phone charger if I need, but so far I have never had the need to charge a phone in the car…..it’s usually in the boot when we are out or I’m working.
Every Series III I've owned, seen, or worked on....quite a few in all....has a lazy voltmeter.
A long time ago (twenty years?) somebody who knows about these things opened up the four aux gauges and discovered how/why they are different from the norm. I can't remember the details, though. I'll try to find that info. And when the change was made from Smtihs to Veglia instruments the unusual design apparently was kept.
On top of that is the bent needle thing, itself a bit of a mystery, which adds to the problem.
Cheers
DD
Doug, wasn’t there something about an “exciter wire” at the alternator coming loose which caused the very slow operation of the gauge? This memory is in the depths of my pandemic-numbed brain….
The exciter wire goes to the dashboard warning light. A fault with this wire can cause a problem in the charging system (no charging, or no charging at low RPM). This will obviously be reflected in the gauge reading. But the exciter wire has no direct bearing on the operation of the voltmeter itself.
volt meter
