Speedometer and fuel gauge replacement tips?

[gordyzx9r]

Finally found a used speedometer and fuel gauge for a '70 Chevy C10.

Any special tips or tools that I'll need to change these out?

The only thing wrong with my current speedometer is that the needle is broken, off. Would it be easier just to swap out the needle? I hadn't even thought of that till now.

And anything to look out for on the connections for these?

[88Stanger]

I think you can just replace the needle if I am not mistaken. I have read about guys taking off the needles to repaint.them I believe.

[leftybass209]

You'll need some sockets, 5/16 and smaller (can't remember the exact sizes). It would help to drop the column a little and you should be able to weasel the panel out. If your paint is nice, you should blue tape everything to reduce the chance of scratching. The speedo cable should just unscrew, and you'll need a wrench to get the oil line off. It should be easier to remove once you start to pull the dash, rather than going from underneath. The wiring plug in comes out by squeezing the sides and pulling.

While you are inside, you should consider all the little things people like to do to improve these panels. Consider a plastic polish for the lens, new bulbs or leds, painting the inside of the tin white (or using reflective tape) and getting new lens grommets (or making them from craft foam).

The gauges themselves are removed with a couple small screws. Pay attention to the orientation of the resistor on the back of the fuel gauge, and where the washers are (there's a few).

You can just replace the needle, but you can determine which gauge is in better condition when you get it apart.

Use light pressure and a slight damp rag (just water) to wipe the gauge faces. The screen printing is easily wiped off and smeared.

Best of luck!!!!

[gordyzx9r]

Well...I got it out, took it apart, cleaned it up, replaced all the bulbs, swapped the guages and:

Speedometer works great up to 35 then it stops.
Fuel gauge went right to empty again and stayed there. The resistor (white block with red strip in the middle of it), only had 1 washer each.

I'll take it apart again, I'm hoping the needle on the speedo is just bent or catching on something. Fuel gauge, ugh. When I interrupt the wire to the tank, the gauge pegs out and goes past empty.

[gordyzx9r]

And now I have about 8" of the inner part of the speedo cable sticking out...

So, did I just lost a speedo cable? Could a stuck needle make it twist from the transmission and cause that?

[gordyzx9r]

Well, the needle was bent and it was getting stuck. Re-positioned it, and now it sweeps just fine. Wish I would have checked that first...grrr.

So, the speedo cable? A complete loss and need to be replaced or is there someway to rewound that?

[gordyzx9r]

So...I attached a drill to the end of the cable, wound it back in. Put everything back together and the speedometer now works like it's supposed to. Just hope I didn't tweak anything.

Now about that damn fuel gauge...

[VetteVet]

.............

Fuel gauge, ugh. When I interrupt the wire to the tank, the gauge pegs out and goes past empty.

The needle should go past full. The gauge works on variable resistance, from zero to ninety ohms. Zero Ohms will read empty and 90 ohms will read full.
As the float arm rises it raises the fuel gauge needle towards full. As it drops the gauge resistance reads near zero ohms and empty.

If you remove the sender wire from the tank unit and the gauge goes past full, it means the problem is in the sender unit. Your float arm may be stuck or the float may have pinholes in it and be full of gas.

Take the sender unit out of the tank and ground the sender flange to the cab or another good ground and with the key on, raise the float arm up and down and watch for the gauge to follow the movement. If you don't see any needle movement then the sender is bad or the float has pinholes in it and is too heavy to move up with the gas. You do have gas in the tank right? .

[gordyzx9r]

Originally Posted by VetteVet

.............


The needle should go past full. The gauge works on variable resistance, from zero to ninety ohms. Zero Ohms will read empty and 90 ohms will read full.
As the float arm rises it raises the fuel gauge needle towards full. As it drops the gauge resistance reads near zero ohms and empty.

If you remove the sender wire from the tank unit and the gauge goes past full, it means the problem is in the sender unit. Your float arm may be stuck or the float may have pinholes in it and be full of gas.

Take the sender unit out of the tank and ground the sender flange to the cab or another good ground and with the key on, raise the float arm up and down and watch for the gauge to follow the movement. If you don't see any needle movement then the sender is bad or the float has pinholes in it and is too heavy to move up with the gas. You do have gas in the tank right? .

There is definitely gas in it...I'll try what you said and see how that goes.