> put in a new voltage stabilizer a new thermostate a new
> sending unit the
> gauge still goes straight to hot in about a min of idle does
> anyone know how to
> rebuild the gauge or is it just too difficuilt
I wouldn't attempt to "rebuild" it, but calibrating them isn't too terribly
difficult. Not easy, but maybe only 4 wrenches on a scale of 5.
If you remove the gauge from the dash, you should be able to see two round
holes on the back, one on each side, about 3/16" in diameter. The holes may
appear to be filled with cork (or covered with tape); or they may be open so
you can see the slots behind them.
You'll need a tool that will engage the slot and press against the side of
the hole, so you can pry the slot sideways with reasonable precision. I
turned the end of a 1/4" bolt in the lathe to create an off-center pip to
engage the slot, but filing down the end of a (cheap) screwdriver would work
just as well.
The adjustment behind the cold side of the scale affects the entire range;
the adjustment behind the hot side affects mostly the hot side. But they do
interact to some extent, so you'll need to work back and forth.
I've not actually done this on a temp gauge yet, but the voltmeter in my
Stag is the same construction, and it came out very well. On it, I
discovered that one of the adjustments was so loose that it would move just
from setting the gauge down on the bench ! I put a drop of fingernail
polish in the hole to hold it in place.
Of course then you'll need some reference values to calibrate to. I'd start
by taking the sender out and measuring it's resistance at various
temperatures. Pick a pair of temperatures, say 140F and 240F, to correlate
to two points on the gauge (the cold line & the red line) and note the
sender's resistance at those temperatures. Then get precision resistors at
those values (or set variable resistors) and a 10 volt power source.
Then you connect the gauge to the power source and the "low temp" resistor,
wait for it to settle (a minute or so at least), and tweak the cold side
adjustment so the needle reads where you want it. Then do the same thing
with the "high temp" resistor and the hot side adjustment. Lather, rinse,
repeat until both readings are spot on. Dab on some nail polish, check the
readings one more time, and put the gauge back in the dash.
Randall
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