1956 speedometer & tachometer cable replacement difficulty

[LA 56]

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.

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[MEL]

Send it to Bob's speedometer he's in Michigan he is the best just expensive he fix mine and tack fuel gage

 

[ICON 56]

Depending on your physical size you would need to get under the dash to disconnect the both. Each are tighten by finger pressure. There is an internal flexible shaft cable that can be pulled through on the speedometer the cable is connected to the drive gear outside (see photo) of the transmission. this would require the car to be jacked up or on a lift. The tachometer cable also has an internal flexible cable the feeds through the firewall into the side of the distributor which connects to a tach gear. You can easily get to the Tachometer inner flexible cable and pull it out to replace it. Or inspect.

 

[doug7740]

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

 

[Frankie the Fink]

Sometimes, if the speedometer gods smile down on you, a cable could have just have come loose on either end creating the symptoms you describe. Still a good idea to lube it if you are so lucky.

 

[cokefirst]

Bob's speedometer does a good job but his prices are extremely high. I broke a cable because the tachometer seized on my car. His estimate, not counting shipping back and forth was $500. I took an old speedometer cable and cut the end off. I lubricated the bushing for the tachometer with some 3 in 1 oil and then used a pair of pliers and carefully turned the drive back and forth. once it was loose enough to turn, I lubricated it again and used the drill to spin the tachometer at 3000 rpm for several minutes. the unit freed up and I was able to reinstall it with a total cost of a couple hours of my time. and a few drops of oil. If you live in a larger metropolitan area, there are still a few speedometer shops around and the old school guys can make you a new inner cable and square the ends up just like the factory.

 

[doug7740]

I commend you for repairing the tachometer yourself instead of paying someone else to repair it for you. Like the speedometer, the tachometer needle moves by the centrifugal force of the magnet spinning around the inside of the metal cup, but since the tachometer has fewer moving parts, it is easier to repair.

doug7740
1955 Thunderbird Blue

 

[Frankie the Fink]

Just for the record you need something like Kable_Ease for speedometer cables, not just any old lube...

Amazon.com

 

[LA 56]

Thank you all. I've gotten the spedo cable out. It was a real PIA getting it off the rt. angle drive on the trans. I ended removing the rear trans. mount to get up to the knurled nut. Then I had another PIA getting the rt. angle derive out of the trans. but it finally came out. I wanted to look at the gear Glad I took it off The gear teeth looked ok but I realized that when I turned the nylon gear in the angle drive it would skip or spin without turning the output end of the angle drive if I inserted the cable into the drive and held it with a pliers. Without holding the cable the nylon gear would not skip or spin an the drive seemed to work ok. The inside of the nylon seems to be damaged/stripped out. I'll order a new 19 tooth gear. Is it possible to lub the angle drive. There is what appears to be a pipe plug on the end where the drive makes the 90 degree turn. Can I remove the plug and grease or oil the drive there?

I'd also like to spin the speedometers by inserting the cable and turning with a drill or by hand but I'm afraid to damage the spedo by turning it to wrong direction. Any one know if that will damage it or which direction is correct and looking at it from the front or rear.

I have many of the same questions related to the tach.
Thanks LA

Similar threads

 

[Tom Alpers]

Thank you all. I've gotten the spedo cable out. It was a real PIA getting it off the rt. angle drive on the trans. I ended removing the rear trans. mount to get up to the knurled nut. Then I had another PIA getting the rt. angle derive out of the trans. but it finally came out. I wanted to look at the gear Glad I took it off The gear teeth looked ok but I realized that when I turned the nylon gear in the angle drive it would skip or spin without turning the output end of the angle drive if I inserted the cable into the drive and held it with a pliers. Without holding the cable the nylon gear would not skip or spin an the drive seemed to work ok. The inside of the nylon seems to be damaged/stripped out. I'll order a new 19 tooth gear. Is it possible to lub the angle drive. There is what appears to be a pipe plug on the end where the drive makes the 90 degree turn. Can I remove the plug and grease or oil the drive there?

I'd also like to spin the speedometers by inserting the cable and turning with a drill or by hand but I'm afraid to damage the spedo by turning it to wrong direction. Any one know if that will damage it or which direction is correct and looking at it from the front or rear.

I have many of the same questions related to the tach.
Thanks LA

Similar threads

You can turn them with a drill, people have done it. And people have done it and damaged their speedometer. There is no reason using a drill to turn the cable to run the speedometer should damage it but I would add this caveat... The speedometer is designed to read 60 mph and to "clock off" 1 mile, when the cable turns 1000 revolutions in a mile. At 60 mph you drive that mile in one minute. That means the rpms of the speedometer is 1000 rpm. I think were people get into trouble with drills is in two areas. They use an electric drill that can turn 3000 rpm, the equivalent of 180 mph and they run it like that for several minutes. The speedo wasn't designed for that kind of "speed" and I would think there's a good chance the little brass bushings it all spins on would get rather warm. The other possible problem is if people don't use the cable but just make an adapter of some sort that they can put in the drill chuck and then stick in the back of the speedo head. Doing that without sideloading the bearings would be very hard to do when holding things by hand so I suspect people doing it that way sideload the bearings, which would not happen with the sloppy cable end driving it. That side load may well make the bearing quite warm. It doesn't seem like turning it backwards should be a problem... but the odometer part wasn't designed to turn backwards except for short distances and usually at very slow speeds. I would suspect it has a thrust bearing to take the loads from the worm gear when it's being driven in the normal forward direction... but there may not be a decent thrust bearing, perhaps just the pot metal housing or some plastic when it's driven backwards. I have not looked at one in a long time so perhaps my thinking is off in that regard.

 

[doug7740]

It doesn't seem like turning it backwards should be a problem... but the odometer part wasn't designed to turn backwards except for short distances and usually at very slow speeds. I would suspect it has a thrust bearing to take the loads from the worm gear when it's being driven in the normal forward direction... but there may not be a decent thrust bearing, perhaps just the pot metal housing or some plastic when it's driven backwards. I have not looked at one in a long time so perhaps my thinking is off in that regard.

Since the odometer drive gear is plastic and the driven gear is metal, there is no thrust bearing.



The metal driven gear turns the side gear which is attached to the first odometer wheel by four plastic protrusions.



The gears inside the odometer wheels are plastic with a metal drive gear between them.





If for some reason the odometer wheels would jam, the plastic drive gear would strip.



doug7740
1955 Thunderbird Blue

 

[John H]

What is the best and easist way to check the spedo gear on the trans without taking the motor and trans out? Speedometer doesn't work took the cable out and inspected it,no kinks. Thinking its the plastic gear on the trans. Want to take it out and inspect it to see if it's striped.

 

[ICON 56]

The Drive gear is located up on the bell housing near the trans tunnel Drivers side.

 

[cokefirst]

to remove the driven gear, remove the bolt that holds the collar of the speedometer cable to the tail shaft of the transmission. Once the bolt is removed, pull straight up on the cable and the driven gear will be sticking out of the bulb at the end of the cable. Check that gear for missing or damaged teeth. If the teeth are damaged, try turning the driven gear in the end of the cable ad see if it turns freely. If you feel resistance, you may have to lubricate the speedometer head. to to this there is a wick you can put a small amount of oil on and it will lubricate this part. You can do this with the speedometer installed but it is easier to remove the speedometer assembly from the dash and do this with the speedometer head removed from the dash. With that speedometer assembly out of the dash, check the speedometer input to see that it turns freely.

 

[My2ndFord]

Are the connector and clip required for the tach cable where it attaches to tachometer? I bought a new tach cable for my 56, but it won't operate the tach. The old cable has the connector and clip. It slides on to the flattened end of the cable core. The new cable has a square end and is too long for the connector and clip and won't fit the slot in the connector. The new cable core fits into the tach, but spins without engaging the tach. It will turn by hand if I use the old connector and clip with just the connector inserted. Was the original opening square? I wonder if, at some time in the past, the clip spun in the tach and rounded out the hole? Thanks

 

[Tom Alpers]

Are the connector and clip required for the tach cable where it attaches to tachometer? I bought a new tach cable for my 56, but it won't operate the tach. The old cable has the connector and clip. It slides on to the flattened end of the cable core. The new cable has a square end and is too long for the connector and clip and won't fit the slot in the connector. The new cable core fits into the tach, but spins without engaging the tach. It will turn by hand if I use the old connector and clip with just the connector inserted. Was the original opening square? I wonder if, at some time in the past, the clip spun in the tach and rounded out the hole? Thanks

Preface, all my comments are for my 57, If you have a 55/56 yours may be different in some aspects.

I'm having trouble following your issue without photos as each end of the cable has aspects of square and flat. If my memory serves, The cable end which goes into the back of the tach has a square end with a bigger diameter spot on it, like a ferule, which butts up against the back of the tach's mating sleeve to prevent the cable from going too far in. In the attached photo you can just barely see the brass ferule on the left side of the photo. The cable end at the distributor has no ferule as I recall.. I think it's basically the end of the cable crushed into a square shape at the time of manufacturer and that slips into the gear that goes into the distributor. I think the clip, if there was one, goes somewhere on the distributor end. My memory is a little fuzzy on that.

On your other question about whether the cable has spun in the tack and wallowed out the hole.... Yes, something like that's possible and it happened to my tach. I was driving one day and the tach needle got erratic for a few minutes and then stopped moving at all. When I pulled out the cable the end of the cable had rounded off.. thank goodness it was mostly the cable and not the tach mating sleeve although I'm sure that has wear too. I bought a complete new cable with sheath (the old one was wrong length and diameter and may have been for a different car). The new cable end has enough meat on it to mate up successfully with the sleeve and the tach works again. Photo shows how the old one had worn down.

 

[My2ndFord]

Thanks for the input. I conclude the core in the replacement tach cable I purchased does not extend far enough to engage the tach. I suspect what was once a square opening has been worn round which is why the new square core won't engage. The original core with the spacer and "clip" extends significantly farther than the new core. I think you can see from the attached pictures what the issues are. I conclude a "new" tach would engage the new cable, but don't think that's an option I'll pursue. I've made a "U" shaped shim that seems to extend deep enough into the tach to engage. Ideally, a new cable identical to the original would be preferred. One picture shows the connector, clip, and new cable, one picture shows the slot in the connector, and last shows the assembled original connector next to the new cable.

 

[Tom Alpers]

I've never seen that kind of end on a tack or speedo cable before. Every online source of parts shows the 55 and 56 and 57 all use cables with the square end. I have never seen one with that pointed spring end before.

 

[My2ndFord]

Did some more research and found: "Ford part # B5A 17306-B Connector and clip. This connector was used on all 1955 and 1956 Thunderbird and 1955 Ford passenger car original speedometer cables."

It appears the replacement cable would work if my tach had a square input as it probably did when new. My original cable case is damaged and they don't seem to be available, now. I was curious if anyone else had run into this problem and how it was resolved. For now, I stick with my shim. Thanks, again for your comments.