To all 6v experts;

Bill W. is finishing up on a 6-12v conversion of a 444...it has already and run under its own power in the process of being finalized and cleaned up. The experience will be documented in a SwEm article * currently in the process of being written, for the benefit of others interested in this conversion.

I seek a few more info items.

Can someone with a fuel gauge confirmed to have come from a 6v instrument cluster please look at the input resistor on the power lead (after removing from cluster) and let me know what value it is. On 12v instrumentation this value was 82ohms. I would like to compare these values(and if they were different). Also, can someone with the documentation compare Part nos. on the two and inform me if they are the same or different...also the sending unit.

From the (German) VDO data sheet **, the gauges are quite forgiving of system voltage variations (from actual power up tests, even when operating a 12v gauge and sender on 6v, there is only a slight drop in indication), so I'm lead to believe the same part (PN) may have been used.

* http://www.intelab.com/swem/Vintage_Volvo_6V_to12V_conversion.htm
** http://www.volvoniacs.org/forum/thread.jsp?forum=31&thread=1111

Thanks in advance for responses!

Hello Ron,

I have a 6-volt gauge in front of me, removed from the cluster. There
is no internal resistor "visible" within the brass housing surrounding
the windings, or anywhere along the power circuit within the gauge. This
is not to say there isn't one. Dissection may show otherwise.

I've done a few 6/12 conversions on 444s, and have never changed or
modified the sender or gauge. My '58 was done in 1971, and there have
been no problems since then. The gauge reads accurately, as well.

Best Regards,
Bearman
www.bearmanmotorsports.com/pv.html

Bearman;

Thanks for the info...please look over the article* I've put together on the conversion...having done this yourself, I would value your input on the fuel gauge and any other issues very much.

Regarding the fuel gauge, I don't think dissection is necessary, I am interested in performance of a 6V unit....(I only have a 12V one to study), I'm trying to confirm that the 82 ohm resistor on the 12V version is the only difference (is same VDO meter movement used in both?), and that a 6V guage may even be run without damage and with acceptable accuracy on 12V without the resistor (because the balanced magnetics design of the meter movement is extremely forgiving of supply voltage variations)...although adding the resistor would certainly be simple.

Since you have a 6V gauge out and on the bench, I would like to ask you to hook it up to a variable power supply set to 6V, with about 100 ohms simulating the sender (I expect that will give about mid scale needle deflection), then slowly increase the supply voltage to 12 and note deflection change. Pix (with permission to use in the article) would be nice too if you can manage it.

* http://www.intelab.com/swem/Vintage_Volvo_6V_to12V_conversion.htm

Cheers

Hi again.
I have just scrounged through all of my 6v lit and none show a resistor.
The fuel guage in conjunction with the sending unit are the only resistance sources that I know of.
I have built many cars and changed many to 12v and none had an external resistor.
After lunch I will check the resistance of each guage and each sending unit and send you what I find.
Ray J.

Hi Ron.
On my 12 volt guage on the backside of the guage, on the center lead strap going to the center of the guage it is stamped 12.
On my six volt guage are no markings.
Usually if no guage change by the auto maker, then the only difference is in the fuel tank sending unit and its resistance.
Hope this helps.

Ray Johnson

Ray;

...good eye!...after I cleaned up the slight surface corrosion, was I able to see the same ⎘] marking on mine...it sounds like you have one of each out of the cluster and can look them over...please compare the resistors on the incoming power leads of both, and get back to me. My bench tests show that there is only the slightest drop when meter is indicating at midrange (sender equivalent R set at about 100 Ohms), and the power is varied from 12 to 6V.....that's because the indicator uses a clever balanced magnetics technique which is highly insensitive to power variations...just what you would want in a car. A beautifully simple, yet effective design!

Cheers

Hi Ron,
Here is what I found. Measured with a Fluke digital VMeter.
6v sending unit: empty=16 ohms, full=200 ohms
6v gauge: 55 ohms from - to + terminals

12v sending unit: empty=32 ohms, full=150 ohms
12v gauge: 175 ohms from - to + terminals

Gauge action is dampened by the mechanical structure of the gauge.
Old gauges used a felt like material for friction. Thats why some old gauges came up to the full mark slowly.

I would tear up my old 6v gauge but someone may need it in the future.

Best
Ray J.

Sorry Ron but the 12v guage was given to me and when I removed all of the wiring in my 6v 544 I just threw it away.
I will look through all my 6v lit and see if the resistor is mentioned.
Ray J.

Ray;

Thanks for the gauge data. The resistor is part of and really internal to the guage assembly so I kind of doubt they would be "mentioned" in literature.

(see pix at: http://www.intelab.com/swem/Vintage_Volvo_6V_to12V_conversion.htm)...the 12v guage does seem to be very forgiving of power voltage variations - even to 6v!...but the big question I'm still trying to answer is if gauges intended for 6 and 12v service had different internal resistors.

Cheers