After the speedometer needle bouncing around for some time and being lubricated by a mechanic, which seemed to help a bit, the needle jumped a lot a few times and the speedometer quit working.
Now I'm hearing a fairly loud scraping noise that gets faster and louder as the cars speed and RPM increase. I assumed that the inner cable for the speedometer broke, but now I'm also noticing that the tach needle is bouncing a little bit and there is an intermittent scraping or grinding noise coming from under the dash or the engine compartment. This leads me to believe that it is more likely coming from the tach cable.
My question is how tough is it to get both the speedometer and the tach cables out to replace the.
If the speedometer stopped working and you are hearing a scraping sound that gets faster as the car speed increases, then the
speedometer cable cannot be broken. The speedometer has two main
parts, the speedometer head and the speedometer drive cable. When the speedometer fails to indicate speed or mileage, the cable may be broken. Most cables break due to a lack of lubrication or a bend or kink in the housing. The cable also might break when the speedometer head mechanism binds. A jumpy pointer, along with a scraping noise, is often caused by a dry or kinked
speedometer cable. The kinked cable rubs on the housing and winds up slowing down the pointer. The cable then unwinds, and the pointer jumps.
To
lubricate the cable and check for kinks, the cable will have to be removed from the housing. It is not necessary to remove the housing from the vehicle. From under the dash, disconnect the housing by its fluted nut from the back side of the speedometer head. Prior to removing the cable from the housing, cover the carpet and upholstery, as the common lubricant is graphite which will really make a mess to whatever it touches. Using long nose pliers, pull on the cable while supporting the housing. The cable should come out easily, unless there is a crimp somewhere in the housing, which could be the cause of the problem by itself.
With the cable fully withdrawn and out of the car, inspect the outer surface of the core for flat and shiny areas. These indicate wear areas, and you can use their position to approximate the area of the housing that may have an excessive bend or kink. To check for kinks, lay the cable on a flat surface and twist one end with your fingers. If it turns over smoothly, the cable is not kinked. But, if
part of the cable flops over as it’s twisted, the cable is kinked and should be replaced.
Before reinstalling the cable back into the housing wipe it down with a clean absorbent cloth and re-lubricate it with a graphite bearing lubricant. Then feed and twist the cable back into the housing. The last 3/8” to 1/4” will require twisting and pushing to engage the square drive at the far end of the cable.
Before re-connecting the cable housing to the back of the speedometer head, put a few drops of lubricant on the wick through the hole in the speedometer head.
doug7740
1955 Thunderbird Blue
