On most, if not all sender units that are fitted to our cars, the
electrical connection does not, as you describe rely on current passing
from the sender shaft to the body through the bearing surfaces. There is
a small hair spring of about 3 turns that wraps around the shaft at its
centre that make a direct connection between the body and the rotating
This is hardly visible unless you remove the resistor former. Not an
easy task I admit. This light coil spring often breaks and a fix like
yours becomes the only realistic solution.
For the record, our sender units were made by Smiths not Lucas.
>Mark, fluctuation of the fuel gauge needle, IMHO, indicates fluctuating
>voltage as the fuel gauge is no more than a volt meter. I got rid of the
>fluctuation by soldering a thin flexible wire to the float arm and grounding
>the other end on the sender body - see attached picture (for your eyes
>only). The explanation is that the current through the sender mechanism has
>to pass from the shaft with the wiper to the sender body. Lucas thought
>their equipment was corrosion free, but it isn't , and one gets a nice
>fluctuating resistance in the bore.
>With the flex wire the resistance is close to nil and also not fluctuating.
>At least this solution worked for me....
>Jack Aeckerlin, The Netherlands
>1964 BJ8 29432
>2010/12/13 Mark LaPierre <firstname.lastname@example.org>
>> Has anyone tried the little gizmo that connects to the back of the fuel
>> slow the fluctuating needle. I would like one for each of my cars but
>> want to gamble on something that doesn't work. The email says it is a
>> product and gives a part number.
>> Anyone try this out yet?
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