Speedometer Question

[SALfan]

Not exactly electrical, but it is a gauge. The speedo in my '69 doesn't move when it's first driven, then it will swing wildly over an arc of 20 mph or so on the scale, then it works fine. My brother-in-law says the lubricant in the cable has dried up and left the thing insufficiently lubricated. Sounds right to me, does it sound right to you guys? If that's it, how do I lubricate the cable? If not, any idea what the actual problem is? Many thanks.

[flyboy2610]

That would be my guess.

[fordman]

confired. unhook the cable from the truck. and then pull the inner cable out. clean and junk off of the cable. dump graphite down into the outer cable alot of it. not a whole tube. but several squeezes from a tube of it. until it starts to flutter out the other end as you hold it up. then reinsert the inner cable and use your fingers to spin it around several times. if it doesnt work as smoothly as you like repeat. until it works right.

[SALfan]

Thanks, I appreciate the help.

[m-mman]

But If that doesnt cure it, check the speedo driven gear.
I have had them with worn teeth (like a razor) and once I had one that have been dragged on the road and had a flat spot with NO TEETH in one area that caused the same symptoms.

[70_F100]

The best lubricant for a speedo cable is a lightweight grease, such as Lubriplate 100 or 105. It's light enough so that it doesn't get thick in colder temps, but thick enough to bond to the core and housing.

All of the manufacturers have used a lube like this for many years.

Do it once, and you or the truck be long gone before it ever needs it again...