1957 Speedometer fixing updated

[Oregon John]

When my speedo started making noise and the needle jumping around, I looked up forum comments. There were plenty, including ones blaming the cable, and one declaring that he had never seen an internal issue [the small drum inside], which I had found to be common on speedos in general. This made me pause and decide to check the cable. This is easier than anyone suggested. If you remove the speedo, or just let the cable hang down, you can feel it with your fingers while you are driving. Be careful not to grab it hard, maybe just gently lay a finger on the rotating tip. If it is not turning, the answer is obvious - replace the cable. I suggest the whole thing, not just the inside, or you will break the new inside again. If while driving, the inside part binds and jerks, you can feel it, and try to lube the outside sheath. Yes, there is a special graphite lube available, but how to do the job without removing the whole cable setup? Maybe get a large syringe or turkey baster, hold it snugly, and squirt? Be ready for a real mess!
My inside cable part turned well, so I sent the speedo off for pro repair. Note that a suggested business, Tacoma Speedometer, replied that they no longer had parts, but referred me to Clawson Classic Instrumentation in Anacortes, WA [www.markclawson.com], which did a prompt job at reasonable cost. Mark also taught me something about these speedos: the apparent lube spot on the back of the speedo is actually a plug, so trying to oil back there whilst upside down under the dash may be useless. He uses a special lube that I had not heard of and advised that the usual bearing lube that we reach for is a big mistake. And once the noise starts, get on the task right away, before more internal wear occors.

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[Tom Alpers]

When my speedo started making noise and the needle jumping around, I looked up forum comments. There were plenty, including ones blaming the cable, and one declaring that he had never seen an internal issue [the small drum inside], which I had found to be common on speedos in general. This made me pause and decide to check the cable. This is easier than anyone suggested. If you remove the speedo, or just let the cable hang down, you can feel it with your fingers while you are driving. Be careful not to grab it hard, maybe just gently lay a finger on the rotating tip. If it is not turning, the answer is obvious - replace the cable. I suggest the whole thing, not just the inside, or you will break the new inside again. If while driving, the inside part binds and jerks, you can feel it, and try to lube the outside sheath. Yes, there is a special graphite lube available, but how to do the job without removing the whole cable setup? Maybe get a large syringe or turkey baster, hold it snugly, and squirt? Be ready for a real mess!
My inside cable part turned well, so I sent the speedo off for pro repair. Note that a suggested business, Tacoma Speedometer, replied that they no longer had parts, but referred me to Clawson Classic Instrumentation in Anacortes, WA [www.markclawson.com], which did a prompt job at reasonable cost. Mark also taught me something about these speedos: the apparent lube spot on the back of the speedo is actually a plug, so trying to oil back there whilst upside down under the dash may be useless. He uses a special lube that I had not heard of and advised that the usual bearing lube that we reach for is a big mistake. And once the noise starts, get on the task right away, before more internal wear occors.

After you unscrew the cable from the back of the speedometer you can pull the inside cable out of the outer sheath. Be careful to not let it touch anything because it will be greasy and black from years of turning inside. It may be dry but will still be have a dirty coating that you don't want to get on anything. When I have worked on mine I pull it out and then clean it off with brake cleaner and then lube it with white grease. You can buy the whole cable assembly if the sheath is worn out but then you have to get under the car and remove the end that is screwed onto the transmission and that is tight area to work in. I've always been able to either relube and reuse the inside cable or replace the inside cable with new and reuse the sheath. When you feed the inside cable back into the sheath you may need to rotate it a bit to get the far end to seat into the transmission driven gear as the far end.

 

[doug7740]

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. When 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 a long nose plier, pull on the cable while supporting the housing. The cable should come out fairly 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

 

[Oregon John]

I don't know if the 1955 speedo cable differs from the 1957, or some are just made differently. But my inner core would not pull out from either end. In fact, it got stuck and required some effort to push back in. So, no lubing easily. Re: the back of the speedo, the lube hole comes plugged, according to the repairman [mine was]. He also suggested that owners quite often over-lubricated through this hole after unplugging.