1930 Hudson Super 8 speedometer, how it works?

[timecapsule]

I'm trying to figure out how the speedometer works in my 1930 Hudson Super 8.  The speed indicator dial rotates horizontally.  However there is no mechanical connection between the dial and the drive portion of the speedo, which has me scratching my head.  This first picture shows the speedo complete, except for the small 4 machine screws that I already removed from the dial assembly, that holds it to the rest of the assembly.  The mounting bracket is aluminium, however as the arrow shows, there is a steel plate below it.  Just below that steel plate is the dial that spins.  The steel round plate is fixed in place.  

[timecapsule]

So here is a picture of the dial flipped over.  It is Aluminium.  "A" shows a diagonal arm that acts as a return stop for the spring loaded dial.  At the top of that arm is a brass screw "C".  Below it is a pin point shaft.  I'm guessing that that is a way of calibrating the speedometer. "B" shows one of two spun areas in the Aluminium.  I'm guessing that they were done at the factory to balance the Aluminium dial.  It's interesting to note the shape of the circular slot opening.  It's offset, and to compensate for that offset the centre portion is offset in the opposite direction.  I've spun that dial many many times trying to figure out why it was manufactured with that offset, but I havent come up with a reason yet.

The "A" diagonal arm is part of the top assembly that houses the return spring.  So where I have "A" pointing to the holes, that was just to sow that it is one piece and the Dial is separate but firmly held in place by that centre pin and brass round ( knurled) nut.  At least I think it is a nut. 

[timecapsule]

So here's where it gets interesting, and confusing for me.  However I think maybe it has something to do with magnetic forces, maybe....

As indicated in this picture, the round piece is a magnet.  But it's really weak.  It will barely pick up a 5/16" lock washer.   it does not touch the under side of the rotating dial.  But the magnet is fixed to that brass centre which is connected to a shaft that goes through the centre of the speedo and is driven by the speedo cable.

[timecapsule]

There is a section of that flat magnet, that is separate, and I can lift it up and even take it out.  But it doesn't seem to supply any clues.

On the bottom side of that removable section is a clip of some sort.  That clip also clips to the centre of that brass portion.  It goes about half way around.  It looks like it could be spring steel.  I didn't want to mess around with it because there doesn't seem to be any way to remove that centre shaft.  It's been pressed in there from both ends from the factory with a designed press.

 

The reason I have the speedo out, is because it was disconnected when I bought the car.  When I put a speedo cable in it, it broke the cable.  That lead me to investigate and the grease in the worm gear that drives the speedo was hard as a rock.  So after some time I got it freed up and working ( on the bench).  When I installed it and took the car for a drive the dial was jumping wildly all over from zero to 90 and everything in between.  Which lead me to where I am now.  Scratching my head.

[rocketraider]

You're on the right track. 

 

Speedometer cable rotates the magnet(s) which induces the speedometer needle, or dial in your case, to rotate and hopefully give an accurate readout of car speed.

 

Magnets do weaken over time and speedometer repair shops remagnetize the unit as part of a calibration.

 

Once you get all the hard dried grease out, use a toothpick dipped in very light oil to lube all the pivot points. Then try operating it again and see if the "jump" is out. If not, may be time to have a speedometer service look it over.

 

I'm guessing you may be in Canada, UK or a Commonwealth country?

[timecapsule]

3 minutes ago, rocketraider said:

You're on the right track. 

 

Speedometer cable rotates the magnet(s) which induces the speedometer needle, or dial in your case, to rotate and hopefully give an accurate readout of car speed.

 

Magnets do weaken over time and speedometer repair shops remagnetize the unit as part of a calibration.

 

Once you get all the hard dried grease out, use a toothpick dipped in very light oil to lube all the pivot points. Then try operating it again and see if the "jump" is out. If not, may be time to have a speedometer service look it over.

 

I'm guessing you may be in Canada, UK or a Commonwealth country?

I'm in BC Canada.  Thanks for confirming my suspicion.  So is there a DIY way of remagnifying that disc?  What's with that small removeable section? 

[Rusty_OToole]

Jumpy speedo usually means a dry or kinked speedo cable. Make sure the cable is hanging in easy curves not bent or pulled up tight. First thing to do is pull the inner out and grease it. You can get speedo cable grease at any auto parts store, at least they used to all have it. Do not put grease on the top 6 inches or a foot of the cable, you do not want it working its way into the speedo.

 

It is possible to make a device to remagnetise . Here is a video using an old transformer, there are other videos showing how to make an electromagnet but this is about the simplest.

 

 

Edited July 3, 2023 by Rusty_OToole (see edit history)

[timecapsule]

Interesting that you should mention not to get grease into the speedo.  In the picture below it indicates where the speedo cable enters.  Inside that brass fitting is a gear that meshed with the gear you can see at 90 degrees which in turn drives the mechanism.  In this picture I have the pressed in oval inspection plate removed.  Inside was hardened grease, preventing the mechanism to turn, as I mentioned earlier.  So after freeing up those gears, I only assumed that that cavity is supposed to be filled with grease.  The inspection plate popped off fairly easily with a micro slot screwdriver.  This lead me to believe that it is supposed to be periodically inspected to make sure those gears are will greased.  So I filled that cavity with John Deere Corn Head grease.

 

But now you're telling me that there shouldn't be any grease in there?

 

Oh btw, that brass fitting is adjustable clockwise and counter clockwise to get the proper clearance of the gear meshing. ( similar to differential backlash sort of) But there is no real way of checking it.  Perhaps you would screw the one gear ( brass fitting) against the other until it was tight, then turn it out a specific distance to get it in the proper position for clearance.  In the picture, I have that brass fitting that holds one of the gears backed off so I could get all the hardened grease out of there.  I screwed it back in to where it was, and it felt comfortably tight or appropriately tight so to say, so I went with that.

 

Edited July 3, 2023 by timecapsule (see edit history)

[Rusty_OToole]

Maybe it was supposed to be full of grease. Newer speedos only have a drop of light oil on the bearings and they don't gum up the same way. Every repair manual I have seen, suggests not to grease the top of the cable and that getting grease into the speedo is bad. But, I do not have a 1930 Hudson manual. If you do, go by it.

[Dan Cluley]

The gears in there also drive the 2 odometers, so if one or both of them is not working smoothly the speedometer will be jumpy.

[paulrhd29nz]

On 7/3/2023 at 7:20 AM, timecapsule said:

I'm in BC Canada.  Thanks for confirming my suspicion.  So is there a DIY way of remagnifying that disc?  What's with that small removeable section? 

Is this by chance your Hudson? 
not to many 30’s badged SUPER 8 

after Packard gave Hudson a cease and diseased order weeks after Hudson announced SUPER 8. 
I’ve seen three in 50 odd years of memories.  All in Canada. 

[timecapsule]

1 hour ago, Dan Cluley said:

The gears in there also drive the 2 odometers, so if one or both of them is not working smoothly the speedometer will be jumpy.

That's a good point.  The tripometer spins nicely.  I guess the only way of checking the movement of the odometer would be to pull it out.

[timecapsule]

17 minutes ago, paulrhd29nz said:

Is this by chance your Hudson? 
not to many 30’s badged SUPER 8 

after Packard gave Hudson a cease and diseased order weeks after Hudson announced SUPER 8. 
I’ve seen three in 50 odd years of memories.  All in Canada. 

Yes, you bet, that's the old boy.

[paulrhd29nz]

Cool. Saw it up close at the Sanich fair grounds last weekend at the swap meet. 
I had  my 51 there and dad had his 19 Essex. By chance was your car a light cream colour that came from the Parksville area?

[timecapsule]

On 7/3/2023 at 4:38 PM, Rusty_OToole said:

Maybe it was supposed to be full of grease. Newer speedos only have a drop of light oil on the bearings and they don't gum up the same way. Every repair manual I have seen, suggests not to grease the top of the cable and that getting grease into the speedo is bad. But, I do not have a 1930 Hudson manual. If you do, go by it.

I'm guessing you've never seen the manual.  It's ridiculous to put it mildly.  295 pages of redundancy. No illustrations or pictures and no index.   Very little specs.  One of the key and redundant phrases in the so called manual is "adjust as necessary"   I also have what's called "Instruction book"  8" X 6" 30 pages.  It's full of information with illustrations and diagrams and photos. Laid out like a normal service manual.  But nothing about the speedometer.

[timecapsule]

3 minutes ago, paulrhd29nz said:

Cool. Saw it up close at the Sanich fair grounds last weekend at the swap meet. 
I had  my 51 there and dad had his 19 Essex. By chance was your car a light cream colour that came from the Parksville area?

Same car I'm thinking because it was a light tan colour with dark brown fenders.  But I got it from Courtney and before that it was in Cobble Hill / Shawnigan Lake area.  It came from Victoria originally.  I've saw your Dad's 19 at the swap meet.  I saw it there last year as well.  Is your 51 a Hornet?

[paulrhd29nz]

From the factory it’s a commodore 6, but under the hood is 52 308 Twin - H with a 262 head. Goes real good. 
come to Pender Island on July 15. We host a car show with the Pender Island Highlanders. Cars, pipes and drums , hotdogs and beer. You can park your 1930 Hudson beside 10 or 12 other Hudson’s. ( my dad and I apparently have a problem ) bring your speedo. My dads buddy is a horologes and works on our Speedo’s. I’ll PM you to get this thread off the hyjacked list. 

[timecapsule]

Just as an update.  I did get a spare speedometer along with the rest of the entire dash, when I bought this car.  At one point I did try to hook it up but the internal threads where the outer speedo cable screws in, were badly cross threaded.  However the speedo drive on that one spins feely.  So yesterday I decided to make a tool to clean up those threads.  I took the handle end of a small file. heated it up and bent the end over to form the shape of a "J"  Very very little room between the threads and the centre section of that drive unit.  But after some time I managed to shape, sharpen, and fit the tool into the threads and after some time using a lighted magnifier, I managed to clean up those threads.  I hooked it up and low and behold the speedometer not only works, but the indicated speed is remarkably close to what my speedometer phone apps says that I'm traveling at.  Probably within one mph. 

I mig welded together pieces of my broken inner cables and to my amazement it works great.  I had to weld two lengths together so I chose the straightest portion of the cable for the weld, because the heat does make the cable stiff for about 2 inches.  Both ends had to be welded on to the new inner cable as well.  The square end that goes into the speedometer, had to be built up in size, since a generic speedometer inner cable from a parts store is not big enough and just spins freely in the speedo drive.  The other square end going into the transmission was made from a #6 machine screw, squared off, with the head cut off.  It took a couple attempts to get the cable perfectly welded in line, in those 3 places, so it rotated without any wobble.  A tig welder probably would have been easier, but I only have mig.  

The reason I went through all this bother is that even though an inner cable would work (once I increased the size of the end going into the speedometer), there were none available locally.  The parts store wanted more for the shipping to bring it in from another Provence than what the cable was going to cost me.  

Apparently, previously I had bought the only two available inner cables in BC, and I managed to break both of them on the original speedometer. 

I'll keep playing with the original speedometer and if I ever solve the stiff rotating issue, I'll let you know what it was.