Speedometer Cable Not Spinning

[Fleetwood Meadow]

I’m trying to get my speedometer working again. I drove it last year and it stopped working halfway through a drive. I bought a new one and hooked it up and it didn’t work. So I made sure everything was tight and the connection at the transmission was loose. Thinking I solved the problem I got in the car and drove and it didn’t work. So I removed the speedometer side of the cable and drove. The cable isn’t spinning. I can spin the back of the speedometer and it functions. How does the mechanism in the transmission function? Do they fail or is my problem somewhere in cable even though it’s brand new and I pulled on the transmission end and the cable would not come out indicating to me that it is connected straight through? 

[hchris]

At the trans end, the cable fits into a square shaped receptacle which is the inside of a little pinion gear being driven by the output shaft of the gearbox.

 

As the cable isnt spinning when you removed it from the back of the speedo, the problem lies in this area. Either you havent pushed the cable far enough into the pinion receptacle or the pinion itself is at fault, possibly damaged stripped or whatever. Normally there is a retaining plate which holds the pinion gear in the gearbox outer housing, so you should be able to remove it and investigate if needs be, but first try and push the cable well into the pinion before you go any further. 

[Rusty_OToole]

Model, make and year of car not stated. So we have to guess everything. Most cars of the fifties and sixties had a plastic speedo drive gear in the transmission. The gear could be changed for different rear axle gear ratios and tire sizes. If you take off the whole cable at the trans, the gear should come out with it. You can then check if the gear is damaged or worn and if the drive gear inside is intact. Since the drive gear is bronze and attached to the main drive shaft it seldom goes wrong.

[Fleetwood Meadow]

I apologize Rusty for not mentioning that. After being on here for years and posting many things I was under the assumption that people would start to recognize my handle. I even am in the Restoration threads talking about my car. This one happens to be a 1952 Cadillac Series 75 with a Hyda-Matic 4 speed.

[JimKB1MCV]

It does sound like either your speedo cable is broken or simply not engaged at the transmission.

 

I've been following your posts here for a while and I'd like to suggest you find yourself a '50s vintage Motors Manual and spend some time studying  the general automobile configuration and repair hints you'll find there.  That will give you a deeper background and help you better understand some of the usually excellent advise you will get here.

 

I really like to see cars like yours being saved and repaired by their owners, and you have come a long way with yours. So many people seem to have  lost the willingness to learn  anything new.

 

Good luck.

 

 

[Fleetwood Meadow]

Jim, thank you for your input. I have a 1954 Motors manual that came in the back of my Meadowbrook. I have used it for specific things when I’m trying to repair things but sometimes I don’t know where to start. I’ve noticed a lot of guys on here are great and I write these things hoping they will weigh in. And then there are the others who’s responses are always to replace it or send it out to get fixed. I will not do either if I can fix it myself. I’m planning on rebuilding an engine and every time I bring something about that sort of thing everyone keeps saying to send it out. It’s always been my thoughts that the professionals didn’t pop out of their mothers knowing how to do it and if they could learn how to do it I can too. But I rely on you folks to give me the direction to go in order to find the solution. So thank you all for your responses in the things I write. I did my tests on the speedometer. My next move will be to go under the car and check the gear. I just hate going under that car. It’s such a process since I don’t have a lift. 

[Spinneyhill]

LoL! It's not the getting under that is the problem, it is the getting back up again! Hope it is only a broken cable. But they don't usually just break. Mine have broken because the die cast speedo head has been swelling and gradually tightening its hold on the input, preventing it turning.

[maok]

12 minutes ago, Spinneyhill said:

LoL! It's not the getting under that is the problem, it is the getting back up again! Hope it is only a broken cable. But they don't usually just break. Mine have broken because the die cast speedo head has been swelling and gradually tightening its hold on the input, preventing it turning.

Cost me $110 learning that lesson...lol

[Fleetwood Meadow]

So I didn’t know that the cables inside the cable housing were different sizes. I took the gear out and checked it thinking it was broken or that some of the old cable was broken off in it but it wasn’t. So I put the old cable in it and tried to spin it without spinning the gear and it wouldn’t because it was the right size. I put the new cable in it and the cable spun inside the gear housing. So that means the cable I bought has a smaller diameter than the original and that was the problem. I checked the speedometer to make sure it will function and I checked that the gear was locked into place properly so when my new cable comes in everything should work properly. 

[Spinneyhill]

Usually, it is a bad idea to oil a flexible drive cable, esp. if dust can get in. More and more dust will be held by the oil (which is a wetting agent) and bog it up. Soon after that, the cable will brake. I learnt that one with my motorbike brake cables: no oil or they break near the handle.

[Hubert_25-25]

This company sells all the parts you need to fix or make a new speedometer cable.  They even sell a small crimping tool for the ends.  There are 3 sizes of inner cables.

http://www.texasindustrialelectric.com/speedo.asp

 

#1) Remove the speedo cable at the transmission.   With the transmission in neutral, jack up 1 rear wheel.  Parking brake off, have a person rotate the raised rear wheel.  You should see the inside of the speedo output on the transmission spinning.  If you can, give the inner cable a twist from the transmission end.  You should see the needle jump if the cable is good and the connection to the speedometer is good.  

#2) reconnect the speedo cable at the transmission.  Disconnect it under the dash.  have someone rotate the raised tire.  You should see the end of the cable spin.  

[Fleetwood Meadow]

The issue is that the square part of the cable isn’t grabbing onto the gear housing. It spins inside it which means the cable is too small. It doesn’t make much sense because it’s a standard Hydra-Matic transmission. 

[Rusty_OToole]

On 7/26/2019 at 10:06 PM, Spinneyhill said:

Usually, it is a bad idea to oil a flexible drive cable, esp. if dust can get in. More and more dust will be held by the oil (which is a wetting agent) and bog it up. Soon after that, the cable will brake. I learnt that one with my motorbike brake cables: no oil or they break near the handle.

There is a special lubricant made for speedo cables. A tube used to cost 79 cents at any auto parts store. One tube is a lifetime supply. Every 10 to 20 years disconnect the cable at the transmission, pull out the inner, wipe it off with a rag and apply fresh lube. Do not lube the top 6 to 12  inches . You don't want the lube working its way into the speedo. Put the cable back in the housing and put it back on the trans. This should be done if the speedo needle starts jumping. Or as a regular part of servicing the car.

[Bloo]

On 7/26/2019 at 4:54 PM, Fleetwood Meadow said:

put the new cable in it and the cable spun inside the gear housing. So that means the cable I bought has a smaller diameter than the original and that was the problem.

 

Can you compare it to the old one? That can be frustrating.

 

1) In just about any transmission, there is a worm gear around the output shaft, and a "speedometer pinion" in there underneath the fitting. You can pull that out. The piece that holds it in  is colloquially called a "bullet". The gear might or might not be able to be removed from the bullet. If you take this apart to inspect the gear, be sure to look inside the hole at the worm gear too. As it's an automatic, there could be a bunch of trans fluid behind the bullet, I don't know. If you have a bad gear, the number of teeth matter, as you might imagine, for calibration. Also, there was very little interchangeability between speedometer gears in those days, so make sure you have the application right, and thirdly look at which way the teeth lean. Getting that wrong and stripping the worm gear inside the transmission is a common mistake.

 

2) The cable might just not be engaging the square hole in the gear like you thought. Sometimes an old cable gets rounded off and looks fine but does not catch until a new cable is used. Sometimes the cable just needs to be shoved into the gear further. Many cars have more endplay in the cable than you would expect, and it is sometimes possible for everything to hook up and feel good, but the cable is still not far enough into the gear at the transmission end. The square hole in the gear could be stripped, too. Measure the square part of the cable if you think it might be wrong due to faulty manufacturing or something. I don't have much advice about this part. It can drive you crazy. Check it for engagement every way you can think of, and nitpick the little details until it works.

 

3) Make absolutely sure the speedometer head is not dragging. Pot metal rotting and expanding around the shaft is one possibility. Another thing to be aware of is that there is usually an oil wick for the part that the cable spins, but it is usually inaccessible without disassembling the speedometer. If you suspect it is dry, send it to a speedometer guy and let them go through it. If you are on a tight budget, and can't do that, you might have to get the mechanism out, get your eyeball right up to it, and try to figure out how to get a drop of oil in the wick (which is probably completely enclosed) without getting it out in the mechanism. If you get a wee bit of oil where it shouldn't be there can be big problems. If a tiny bit works its way out and gets on the magnet and drum, the speedometer will peg and maybe bust the needle off.