Speedometer Cable

[Thom]

OK, as I continue to try to determine why my power door locks do not work, and how to remove my fuel tank sending unit thru a 2" opening I will move on to the speedometer issue. My speedometer needle bounces around until I reach about 40 MPH and then it smooths out. I recall that back in the 60's that they used to use graphite to ease that problem. Don't know how they did that or if it still works. What I need to determine is if the speedometer cable may be defective and if so, am I in over my head trying to replace it. So far I have been unable to correct the issues with the sending unit or the power door locks so I'm not too confident with the speedometer issue.

[wdaly]

Once again (from memory) you should be able to reach one end of the speedo cable from the engine compartment very top left corner (driver side/windshield).  I'm pretty sure a cable from the transmission attaches to another cable to the speedo.  This should be a 'typical' GM (Monte Carlo-type) set up.  In my case I used the location of the 'mating' to convert from speedo cable to electrical wiring for a Digital Gauge.  This area should be in the engine compartment right in front of the Driver's location.

edit:  OK, as far as the exact location of the mating connector - follow the cable from the transmission up to the engine compartment and you'll run into it.  HOWEVER I may be wrong about thinking you can pull the speedo cable out from engine bay from the actual gauge as this cable may only be removed from the instrument gauge side which would require Removal of the dash gauge.  At any rate if you do get the small cable out (not the one coming from the transmission) simply greasing it with speedo cable lubricant should fix the problem!🤪

Edited July 3, 2022 by wdaly
more info

[Thom]

Thanks wdaly, I did locate the speedometer cable right where you said it would be. That project is now on my ever growing list.

[wdaly]

I saw a Youtube video for checking the smaller speedo cable on the GM cars.  They attached the engine compartment cable end to a drill (I think in reverse mode)- with another person viewing the speedometer in the dash they started the drill to check the operation -  if this smaller cable was the problem.

The actual cable is a springy metal.  The lubricant was a graphite powder (?).  It sure would be nice/easy if you could simply pour some graphite into the cable cover and then use light air pressure to distribute it / no need to remove the actual speedometer gauge..........  😑