Goofy speedometer

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daren007

Well-known member
Today my 30 A speedometer started acting erratic. This has never happened before. The speedometer has always operated as it should even in cold Minnesota weather. It is jumpy as if the cable needs lubrication. Todays outside temp is 96. Will the drive cable do this when hot? I will have to wait for cooler weather to see if it returns to normal meanwhile your thoughts.
 
Two items are possible and I have had both! My car had the original speedo cable and outer part and it had been kinked at some time. The speedometer jumped a bit. I got the kink straightened got some graphite and really lubed up the cable and got it going for a while, but the kink I fear had a memory and came back. With that said, while I had the speedometer pulled down to replace the connections at the top end, I got a little flat head screw driver and turned on the speedometer input a bit. It was kind of stiff, my thoughts are it should turn easily. Talked to my cousin who also has a model A and he suggested to me, to take the one screw out of the speedometer back and fill it with wd40 as best as I could and just let it sit face down for a day or two. I did it and got my screw driver in the input again and just started turning and turning and it did loosen after a while, yet I think I was just lucky. I know there is a small thin metal cover at the bottom and I also remove it and the grease inside was hard. I did the same thing with wd40, and used some permatex to reseal the thin plate, put everything back together and no jumping around. So for me, eventually, it was two things, the speedo cable had to be replaced and the speedometer just getting tight with dry lubrication that I was able to loosen up.
 
Yesterday it was just fine. Today the speedo is erratic constantly at all speeds. This is something you would see in cold weather but I would think not in hot weather.
 
DHZIEMAN said:
Two items are possible and I have had both! My car had the original speedo cable and outer part and it had been kinked at some time. The speedometer jumped a bit. I got the kink straightened got some graphite and really lubed up the cable and got it going for a while, but the kink I fear had a memory and came back. With that said, while I had the speedometer pulled down to replace the connections at the top end, I got a little flat head screw driver and turned on the speedometer input a bit. It was kind of stiff, my thoughts are it should turn easily. Talked to my cousin who also has a model A and he suggested to me, to take the one screw out of the speedometer back and fill it with wd40 as best as I could and just let it sit face down for a day or two. I did it and got my screw driver in the input again and just started turning and turning and it did loosen after a while, yet I think I was just lucky. I know there is a small thin metal cover at the bottom and I also remove it and the grease inside was hard. I did the same thing with wd40, and used some permatex to reseal the thin plate, put everything back together and no jumping around. So for me, eventually, it was two things, the speedo cable had to be replaced and the speedometer just getting tight with dry lubrication that I was able to loosen up.
Click to expand...


That one screw at the back is a blind hole.


You have to drill to get to the mainshaft to do any good with lube into there.
 
daren007 said:
Yesterday it was just fine. Today the speedo is erratic constantly at all speeds. This is something you would see in cold weather but I would think not in hot weather.
Click to expand...

Have you disconnected the cable from the back of speedometer? Sometimes when put back together, the connecting nut is tightened to much. This could cause cable to bind within speedometer.

Try lubing cable, and not snugging down nut, only takes a few turns.
 
Hay what it is that the bushing in side the speedometers are all dry and the best thing to do is have it serviced. You can try to oil it from the back but that will help some but it will always come back to the same old thing. If you get it total service all the bushing and main parts are cleaned and it will be good for years. If you need it serviced I have a 2 day turn around. papanick. But first check the cable.
 
My speedometer jumps around sometimes at low speed. What is the best lube to use on the cable. I have just used grease in the past.
 
wmws said:
My speedometer jumps around sometimes at low speed. What is the best lube to use on the cable. I have just used grease in the past.
Click to expand...

I would pull cable out at dash. Clean all the old grease off of it. Than use some white grease.

I have seen a lot of Model A’s, including our 29 that have had the same problem. From first starting out up to about 5 mph speedometer would jump. Once you get going, problem goes away.

Tried rebuilt speedometer, new cable, grease, still had issue? Enjoy.
 
A cable down to its last threads will make the speedo jump around.

From a watch maker forum on servicing:
"If they are obsolete, or uncommon (like my Seiko 6309's, my old Waltham 100 Jewel, etc), then they go every three years, or when I remember, whichever comes last."

After 90 years the speedo might be a bit dry.
 
This is not a steady tic tic that increases decreases with speed but random jumping (for lack of a better definition)
 
daren007 said:
This is not a steady tic tic that increases decreases with speed but random jumping (for lack of a better definition)
Click to expand...

My vote is for cable binding. Pull it out of its housing, clean and inspect for wear and lubricate with copious amounts of lithium grease or graphite.
 
Ok I have the speedometer head apart. There is (was) a bind on the main shaft. Now a new problem. I just could not leave anything alone. I moved the calibration thingy. Now I need info on how to reset it. I have a drill of constant revolutions I can drive the speedo with but I need to convert revolutions into MPH. Help.
 
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