Pontiac renovations, part 7.

After removing the wiring from the engine bay, I started work on removing the old wiring from under the dash.

Spaghetti. Old, dusty spaghetti.

I removed the fuse box. Under the dash should be significantly more tidy than it is; a lot of the wires had been pulled down out of the loom and were just left to dangle. I also undid the three-set of gauges from under the dash, as there is no real reason to have them there.

Trio of unnecessary gauges.

I heated the bulb of the temperature gauge with my hot air gun to test it. Still, good, it may end up in another application. The oil pressure gauge worked fine so found a home on my lawn tractor. The ammeter, which had never really read much at all was connected incorrectly (in line from the alternator) which would explain the lack of movement.


I filled the hole from the oil gallery where the old takeoff pipe was for the oil pressure gauge, until I have a replacement pipe. This is simply so I do not empty the oil pan all over the floor when I spin the engine over.

The fuse box (and lid, found under the driver’s seat, sadly covered in paint) is quite comprehensive for the age of the car.

The dash looks better without the gauges, the engine compartment is similarly tidy. I need to investigate the wiring that goes downward under the body as all the wires destined for the back of the car run up above the driver’s head.

The amount of wires in the pile, steadily growing. This represents most of the wire from the fuse box and under the dash.

The dash cluster is held in with 4 nuts, moderately accessible from up underneath.

I clipped the wires from the back of the dash to provide better access and removed the cluster.

Not a reproduction item. January 1951, and they had built 4000-odd cars by that time. Needed to be ready for the new model year!

Further disassembly of the gauge cluster to remove the side gauges and clean the perspex lenses. Over the years they have been wiped a lot of time and have become scratched. On the inside, a fine haze was apparent.

Part the way through, to show comparison of clean versus dirty lenses.

The reason for the haze on the lens would become apparent later on.

The speedometer frame had ghostly images of the numbers, faded into the paint. A little polish saw the paint clean again.

Gently buffing the scratches out of the speedometer face with my polishing wheel in my twist drill.

All clean! The improvement is immediately visible. I still need to take it apart and redo the satin black paint where it has all rubbed off over the years.

I connected my air line up to the oil pressure gauge. It’s a mechanical, Bourdon-tube device. It still registers correctly.

I then tried connecting up the other gauges to a 6V power source to test if they were still operational. Quick testing with a multi-meter showed both had at least one failed coil. The haze on the inside of the lens was from the enamel insulation on the wire having caught fire. Previous owner had connected the dash up to 12V when they did the conversion. That must have liberated quite a lot of smoke- and will be the reason for the additional gauges.

Luckily the coils are secured to the armature with nuts and bolts. I removed one coil. The failure is easy to see.

I modified my twist drill to have a cammed section on the chuck (made from electrical tape) that would operate a microswitch every revolution. The switch then in turn operates a small mechanical counter.

Counted the number of turns of wire on the bobbin. It had burned up and split in three places.

Took my micrometer and meaured the diameter of the wire. 7.2 thou’, which is 33AWG. Being as the gauges were both inoperable due to having been burned up, I decided to re-wind them for 12V instead.

36AWG enameled copper wire, with half the cross-sectional area of 33AWG, and twice the resistance per foot. Winding twice the number of turns of this onto the bobbin will make it suitable for 12V operation.

I stripped the enamel off the end of the wire with sandpaper, then checked the end of the wire for good continuity with my meter. This end contacts directly to the metal of the coil bobbin.

Carefully wound the wire on. This was a moderately slow procedure because I was manually guiding the wire as it wrapped and the cam operates only briefly so the counter is not actuated enough to count over about 100RPM.

Tested the end to end resistance of the coil. 26 Ohms, in the correct ball park expected from this gauge of wire.

The second coil, which did not catch fire but charred significantly was also removed.

It was unwound- this side has more turns.

Again measured to make sure it was the same gauge of wire.

Carefully wound on, counting every turn, trying to make the winding even. Nearly out of space!

Tested for resistance- the number of turns being more, the longer the wire and the greater the resistance.

Fitted both coils back into the armature and soldered them to their pegs.

Through a moderate resistance, the gauge now reads properly! I need to calibrate it- the service manual provides the curve of the thermistor in the engine bay per temperature. I can take the three calibration points (at the top of the scale) and set the coils up accordingly. They are adjustable on slides to set the gauge up to read the correct deflection per current passed.

The frame the gauges connect to was a little worse for wear. It wasn’t painted very well to begin with, the brown staining from where the gauge had burned was evident and the heat from the dash illumination had made the paint in that vicinity all flaky, which was getting onto the inside of the lenses as I moved the dash about.

I rubbed the old paint back, to remove loose paint and provide a good keyed surface.

A couple of coats of Rustoleum Heirloom White later (a remarkably good color match) and the frame is looking really nice.

At the same time I heated up the paint and windscreen washer bottle holder (the evening was a cold one, not far from freezing) in prep for paint.

A nice gloss Sky Blue. The frame should have a yellow sticker on the front for screen-wash instructions. 

While that was drying I vacuumed, shampooed and generally cleaned up the back of the passenger cabin.

I was puzzling over the headlight switch. I needed to remove it from the dash as it was stiff to operate. However, I couldn’t figure out how to pull it out. The knob wouldn’t fit through the escutcheon after the mounting screw was undone.

Turns out there’s a spring-loaded pin in the back of the mechanism that presses a spring-loaded collar out of the way and allows the entire knob and shaft assembly to be pulled from the switch.

I took the switch to pieces, lubricated and cleaned it as all the old grease had dried up and was more of a hindrance than a help. Sadly the rheostat is only a few ohms, designed to dim a fairly heavy load (10 4W bulbs), and will have very little effect on the LEDs that have been retrofitted. At least it can be used to turn the dash on and off.

I polished the plastic and chrome, cleaned the grip with a brass brush and polished the locking screw as it is visible when the switch is pulled out. Not bad looking now.

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