1948 Chrysler speedometer not working

[HCD]

I have a 1948 Chrysler New Yorker that Ive changed the speedo cable and speedometer is still not working. have also lubed the port near cable to cluster. Before it wasnt working at all, now it pegs to 100 when moving. I have a good shop manual but it doesnt have any info regarding speedometer. Im pretty sure the cluster itself will have to be rebuilt or replaced. Anyone had similar problems? any input appreciated.

[soth122003]

How long has the oil had time to soak in? Going from not working to pegging at 100 says it needed lube, but it might need more time to completely lube all the parts in the speedo. Granted it will probably need a rebuild, but you might want to give it a little more time to soak in and maybe it will work as needed, but probably not accurate. It might also help to slowly exercise it by using a low speed drill to turn the cable and work the speedo at a low speed.

 

Joe Lee

[Sam Buchanan]

It's possible the little clock spring that controls the needle has broken or come loose. So the needle "sees" the magnet spinning and has no spring to keep it from hitting the century mark.

[HCD]

replacing the speedometer cable was a real pain to replace, especially at the transmission. I was hoping that would have fixed the problem, if adding more lube doesnt work, Im afraid the cluster will need replacing or rebuilt.

[Eneto-55]

When I tore down the speedometer on my P15 (intending to just refresh the reflective paint) I found that what I guess to be white lithium grease was completely hardened. There was a lot of it right in the 'clock spring', so it wasn't able to perform normally.  I had to use a small jeweler's screw driver to carefully chip that stuff off of the spring. (Maybe not the problem with yours, if it was working correctly, then started doing as you described - my car had sat already for at least 40 years by the time I opened the speedo.  Plenty of time for that grease to harden like that.)

[HCD]

On 1/28/2025 at 1:17 PM, soth122003 said:

How long has the oil had time to soak in? Going from not working to pegging at 100 says it needed lube, but it might need more time to completely lube all the parts in the speedo. Granted it will probably need a rebuild, but you might want to give it a little more time to soak in and maybe it will work as needed, but probably not accurate. It might also help to slowly exercise it by using a low speed drill to turn the cable and work the speedo at a low speed.

 

Joe Lee

[HCD]

I was able to get a wd 40 straw into the lube pipe behind the speedo cluster a week ago and get more lubrication in there. Hopefu;;y if all it needed was more lubrication this may get it working again.

[Los_Control]

Thanks for the follow up .... I also need to work on my speedometer and was interested in others opinions on how they disassembled it and if any surprises?

My main concern is removing the needle without damage ... if there are any tips?

 

I have 2 different speedometers for my truck and there may be some differences but I assume they will be built similar as a car.

1rst speedometer on the bench with cable and drill, does nothing .... no movement of the needle at all.

2nd one it just jumps from 0-20 ... mostly just sits on 0 and jumps sometimes while the needle does vibrate when not moving.

 

I expect the 2nd one may have the same issue as @Eneto-55 describes and what I hope to find ... just open it up and give it a good cleaning.

I'm expecting to find something broken in the first speedo ... will be a experience opening them up. and then see if parts are available.