Recently my truck makes a noise I think from the speedometer cable. While driving along I can hear a loud whirring noise like a uncoiling of an over wound spring. It comes and goes and when it happens my speedometer needle kind of bounces around. I suspect this means my cable is bad but before I order a new one is there another possibility I should check first.

 

Sounds like it is the cable for sure. You might try lubing it before replacing it, although it is just about as much work to do that as replace it.

 

It sound like the cable could be running thin on lubricant. If it is it's an easy fix. Buy a tube of graphite speedometer lubricant, pull out the cable, force the graphic down and reinsert the cable. It's messy but cheap. If it doesn't fix the problem then I would try a new cable.

 

You could have a speedo head thats dry. Remove it from the truck. Where you screw the cable on, you'll see a small plug going in 90 degrees to the cable. Scrape out the crap and you'll see the brass plug. Remove it by picking at the edge of it gently. Sometimes you need to take a flat screwdriver that a little larger than the hole and try to twist it out. Don't drill it out as you'll put metal chips into the speedo. When you get the plug out, there's a wick in there that you add a few drops of 10wt. oil to it, something like 3 in 1 oil or sewing machine oil. Put the plug back in and re-install in truck. While it's out is a good time to clean the cluster. Also pull the core out of the speedo cable housing and look for kinks or frays. Both ends should be square tipped. If it's ok, lube it with dry graphite and re-install in housing . You may have to play with it to get the other end to seat in the driven gear in the tranny. it will go. You might want to pull the drive gear housing out of the tranny and inspect. Make sure the gear isn't worn to a concave appearance. If it's fine, put it back together. If it's still making noise, give a little while for the oil to lubricate things. If it's still there after a few days, I'd say the speedo head is worn. If so, take it to a speedometer repair shop and have them go thru it. Good speedo heads are scarce these days, so repair what you've got.

Barry

50 F-1

 

The speedo cable will come out of the housing. I can;t remember from which end, Myrphy's Law says its probably from the gauge end. Pull out the cable from the housing, clean it up with brake clean, carb, clean ,etc then lube it up. In the past I've had great luck with the Lubriplate white lube (alot of people use it as engine assy lube). Back when I worked at dealers I had some special adapters that would screw into the tranny end of the speedo cable and had a grease zerk on them, then I could use a small grease gun loaded with Lubriplate to force grease into the housing without ever having to stand on my head under the dash to remove the cable.

Good luck with it, its a fairly easy repair
Bobby

 

Go really easy with the grease. Too much and it will creep up into the speedo head and make a mess.