The Stovebolt Site Forums The Shop Area General Truck Talk 1950 Chev truck speedometer

Anybody take one of these apart, I was hoping to hear from Jeff of the teck tips regarding the subject but maybe he is not around.
I have two that are not working, wonder if the magnet loses its magnetism over time as there doesn't seem to be anything wrong, the odometer works on both as I have one in the vehicle etc and the one taken apart the odometer works. There must be a common problem with these gauges which may be affected over time...any ideas...Glenn

I took one apart after breaking the needle shaft.

They're not hard to take apart and reassemble, but I understand from Jim Carter's speedo rebuild guy that restoring the magnetism isn't that easy. Get it wrong and it won't work or will indicate a totally incorrect speed. Re-decalling (notice the word I just invented?) is probably within the capabilities of the average shade tree mechanic, but getting the speedo to indicate the correct speed may not be without some special skills/training. I get the idea that remagnetizing them is a closely guarded secret.

I wound up buying a remanned speedo.

i thought that restoring the magnetism was quite simple and straight forward

the soft iron is meant to be saturated, you cannot over magnetize it

so what you do is get a strong magnet and stick it on for a couple hours and go do something else
then come back and pull the magnet off in a clean motion
put your speedo back together and you should be good to go
mine used to read only about half the correct speed, verified that the ODO was counting miles up perfect so it must be weak magnet only
now it's bang on perfect speed

i put the magnets on so that each end of the speedo magnet was one pole N or S of the bar magnets, the Amazon magnets are so strong it either didn't matter that you get the original N/S figured out, or i got lucky

stack the bar magnets so that they bridge to the speedo magnet
you do not need to remove the magnet from the speedo, you need only get the number wheels and the metal cup out of the way

best of luck
-s

I rebuilt mine recently... was a p.i.t.a.... they work. Or atleast they did before i pulled the engine out.

Forgot to add the pic i just took

by far the biggest problem is removing the speedo from inside the dash, i am not a big person and i find i can barely manage
how is a normal size mechanics suppose to get it out?

i must be doing that part wrong
-s

Im 6'3" and just getting in the truck and sitting in it is a challenge. I think people were amller back then..

Now you've done it. You've let the cat out of the bag and ruined the livelihood of numerous speedo builders.

thanks for the comments, I had a feeling that over 60 years the magnets could lose their original potential, now I will just do some experimenting and maybe ending up buying what I need, its all part of the fun