BiMetallic gauge repair
Does anyone have a supplier for the fiberglass insulated nichrome wire?
Looked on Amazon and did not see anything
I suppose one could get very fine fiberglass and pull out fibers coat the nichrome in lacquer and roll the nichrome in the fibers.
I bet the nichrome in my now DOA IVR wore through the insulation at one of the bi-metal edges made contact and melted or wire through. ( Nichrome was broken in one of the wraps at the edge of the bi-metal)
Yeah? nope,,, that wont work. The lacquer would be far too stiff. Movement of the bimetal would be restricted. The lacquer might melt and smoke/smell from the heat. The winding in the mechanical limiters is different too. 50 ohms total resistance in that wire length. I must point out that the spiral wound insulation on the wire is many strands of way less than a human hair. I would unwind it to expose the wire and pinch off the excess fiberglass with fingernails.
Many years ago, Someone said this insulation was a blend of fiberglass and silk. To this day I dont know if that's true or not. Anyway...,
Some of you might go Google searching and find the same guy I found years ago. He can sell you a book of info and/or some wire but... be warned. The wire he has to offer is 1.2 ohms per inch. A little over 16 inches is required to get between 20 and 20.5 ohms. That's a lot of wire to wind into a A-body gauge of 20 ohms. His wire is made for different gauges with a longer bimetal beam.
And beyond that, The service techs 3 level tester is not enough to calibrate a gauge. That was just a tester to say replace the gauge or not. You have to have decade resistance box if you want to prove all the hash marks on a gauge you renewed, especially if you used a different wire.
decade resistance box | eBay
Can this get more complicated? Yep! Solder wont stick to ni-chrome so the wire is tig welded to the head of the stud. These metals work harden when welded. Vibration and movement will cause the wire to break. That is what the dollop of cement like chit on top of the weld is for. Wire movement is away from the weld.
So... Yeah I used that guys wire for a while and managed to fit Approx' 16 inches of it into A-body 20-to-20.5-ohm rally gauges and made them work right. Beam covered nearly end to end with wire.
Thing about classic cars is they should be soooo simple. It's when you get into the
engineering of automatic transmissions, and instruments, and such, that you just have to say, "Damn". I learned, fix the water pumps and chit that I can fix, Leave the more complicated to those that do that.
