Sticky speedo - lubricate?

[ianmack]

I have an early ‘54 car with gold dash and small speedo. It sat for years before I started using it and even now is lightly used. When I first worked on it the speedo didn’t work at all. The needle had stuck in the rest position and I managed to free it off. It worked ok last year but the car has now been sitting for several months.

0n a run the needle moves up as usual but then tends to stick and can sometimes remain at the maximum speed reached for the rest of the journey. When I stop it may not return completely and sometimes even needs a short reverse to zero it.

The question is what to do about it. I could use the car regularly perhaps, or maybe spray its innards with some kind of cleaning product. I’m concerned that the wrong product could glue it solid. What do others recommend?

[MCYorks]

It's probably old oil that's gummed up on the needle spindle and causing it to stick. It could well have gone 67 years without the speedometer ever being cleaned. If that's the case it's not surprising if the original oil is past its best
Applying a small amount of light oil to needle spindle may free it up. The emphasis being on small, as too much oil can cause other problems. I've used 3-in-1 oil in the past and that worked. Also has the advantage that you don't have to dismantle the whole unit, but success usually depends on how bad it was to begin with.

There are some really good guides on the web regarding overhauling Smiths speedometers. If you feel confident doing that. It's important to take care because the speedometer has some rather delicate parts, like the hairspring, etc. So it takes some patience and a steady hand, but it can be done.

[ianmack]

To update this post, fairly regular use since the spring has seen the speedo gradually return to normal activity without dismantling it. It will soon be time to put the car way again so I’ll see how it fares this winter.

[gtt1951]

Hi, your initial comment about the needle being stuck in the rest position - I've got 2 early dashboard cars (and a spare instrument cluster) and have found that the needle actually embeds itself on the rest post! It looks as if it chops its way in.
If you look very closely, you may find a fine "cut" in the post.
With care, you can take off the front bezel and remove the glass. This will give access to the post and the needle. Smooth the post with some fine grit paper and, at this stage, you can repaint the speedometer needle if the paint has been flaking.

Also, you might want to replace the speedometer cable - these are available - as it might be this that has a sticking inner drive cable inside the sheath.

Regards, George.

[ianmack]

Thanks George I’ll bear this in mind if it sticks at rest again. The cable was lubricated when I assembled it and I think it is in good condition. A poor cable will more likely cause erratic swinging of the needle rather than sticking.

[don58van]

There is no mechanical link between the input from the cable and the spindle that the pointer is mounted on. Therefore any efforts to unstick or lubricate should be directed toward the pointer spindle -- that is, the bearings closest to the speedo face. They should be cleaned and lubricated (with great care).
Don