The Stovebolt Site Forums The Shop Area General Truck Talk 1950 Speedometer question

Couple days ago the speedometer went haywire on my way home from work.

Just before I got home it looked like the needle went all the way over to the right then rested facing straight down past the 80.


I disconnected the cable, lubed and reconnected

The odometer still worked but the needle would just barely move towards 5mph, 10mph and hard stop.

I disconnected the cable.


Today I finally got a chance to remove it and take a look.

So here are my questions..
When testing by hand should you move the hub on back counter or clockwise?

Here's a quick test I just did. Maybe some can tell if this is repairable or toast.

...test...Quicktime

...test..non quicktime...

before that test I removed the needle and reset it back to o

Thanks

Did you check the needle shaft spring to see if it came loose or broke? That is the tiny spiral spring behind the face. I have to turn mine counter clockwise. Another thing to check is the little brass plug on the back of the unit of the speedometer head. You can remove that plug VERY carefully. There is a small felt packing (washer) in the hole. Remove the the felt and clean it or replace it and place a few drops of light machine oil on it and replace the plug. If that shaft spring broke the unit is toast and you will need to get a replacement unit. Classic Parts has the best price I've found on replacement units so far.

I thought there was a stop on mine to prevent it going backwards from zero.

The spring intact ...pic...

I put it together after resetting the needle and went for a quick drive down the street. Speedometer did not work but odometer will.

At rest the needle will go both ways , I don't know if it did that before
QuickTime video


Maybe something broke in the can?

I am not an expert on these but I have played with some of my spares. The input shaft and the needle shaft and mechanism are concentric. There are bearings that take the thrust and keep the two functions separate. On one of my units, I believe pushing in on the area where the cable drive goes in will apply torque directly to the output indicator shaft. That sounds like what happened to your when you were driving. If that is the case, some of the bushings or bearings are worn out.

Thanks

Your correct about there being a stop. I've been messing with the broken one and a spare I have. I don't know if the spare s any good.

But it has a stop at 0

...here is a pic to compare...

I ran out of time today. You know how much fun it is to remove the speedo.

I tested the spare with a drill and it looks like it might work.. Just not 100% sure because the hub on the back was frozen but I got it free.

...here is the test with the spare speedo..


Didn't have time to install it for a drive test.

Just left it out and reinstall the choke cable so I can drive it the next couple of days to work. I have a iPhone app I can use for speed.

RE: the copper plug over the oil hole. You'll probably booger it up upon removal. I re-plugged my hole with RTV sealant.

Thanks for the tip

I was looking at that plug yesterday
...pic...

When I go back together with everything I'm going to use the knurled nuts you suggested a while back.
...pic...
...pic...
Should be a lot easier to remove the gauges that way in the future.

Thanks for that link ED

It's helpful
Denny looked at a few of my pics and noticed the shaft(spindle)
Had become separated from the speed cup ( now I know the name from the link above)

...pic...


So looks like I'm going to try the spare. Ill get it all lubed and inspected. I ll put my old odometer wheels on the spare to keep my mileage going.

If the spare won't work ill spring for the repo at classic parts $120.00




Also going to clean relube the cable, the initial cause of the problem

Anyone know what type/weight oil to use in the plug n the back?

I used light weight machine oil.....like 3 in 1 or sewing machine oil.

got the spare put back in today.

used the old odometer wheels on the spare to keep the mileage up.

first test drive was OK..the low range seems a little off,
hopefully this will work out.

it is not fun getting that thing in and out on an assembled truck with a wiper motor right behind it.

thanks to all.