Speedometer noise

B

Bates51

Junior Member
What is the preferred lubricant for a Model A speedometer? We lubed the new cable prior to installing and got the speedometer working but now it is making a moaning noise and wants to swing wildly at about 15mph. Any thoughts?
 
When the speedo swings "wildly", you canbet the magnet it sontacting the drum. The friction is way more than the forces induced by the magnet spinning in the drum so it gets a big kick, then trturns to normal until the next contact. I have two speedos that do that and one of them has just been "rebuilt" by an American guy who I won't name. It seems tome that all these guys do is makeit look pretty and if the drum moves, they think all is well. Both of my 'rebuilds" are no more accurate than the core I sent foir repair. Disappointing!
 
If lubricating the cable did not fix it, I'd say lubricate the speedometer itself.

Not that hard to do. Remove it from the instrument panel, take the back cover off, look for some small brass cup-shaped plugs.

Pull them out by clamping a small drill bit into a vice, the gently push the small brass cup on to the tip of the bit and twist a bit, then pull up. The cup will stay on the end of the drill bit.

Drip some light oil into the hole. You may find a wick in the hole (should find). Remove it and clean it up, if you want, then oil well. Then tap the brass cup back in place.

A light bit of grease in the gear area (remove cover to see gears).

Reassemble in car.

If the shaft inside the speedometer binds a bit, it will make the speed wheel swing up and down because the speedometer cable itself twists up like a spring a bit, then releases and spins the speedo a bit faster.
 
Be especially careful not to use WD40 on the pot metal castings as it will make them swell up and your speedometer will potentually sieze. Use oil!!!
 
I used used red tacky grease on the cable. BUT....there is special speedo cable lube
that is still available if you choose.
 
Thank you for responding. I have the speedometer out of the dash and on the next dry day I'm going to drive and see if the noise is gone. If it is then I will lube the gauge itself. Again thanks.
 
I use a light oil like 3 in 1 to lube the input magnet shaft and the drag cup. Any light grease can work on little gears. Generally the old zinc castings usually swell and cause the shafts to seize or get too stiff to rotate. The other problem can be if the input magnet shaft bearing surfaces get worn too far, the magnet can make contact with the cup. Some folks just find another one with relatively tight bearing surfaces and rebuild that. I've seen a lot of used ones on flea pay but it's always a hit or miss purchase. Some of these old units had a hard life. A lot of them are likely seized up.
 
Sewing machine techs do not like 3 in 1 oil used in sewing machines, it gums up the machine, they have a special oil !
 
I've owned a sewing machine for a long time and use only the crystal clear oil. 3 in 1 is just a light oil but it's not as clear as sewing machine oil. When you work with fabrics, you don't want oil on the fabrics but oiling the machine on a daily use basis makes it hard not to get oil on the fabrics. The clear stuff will wash out with no staining and that the reason it is preferred.

Oil is a product that may or may not have additives depending on what it's intended to lubricate. Since oil is refined, the price of the product is based on how refined it is and what it has added to it. I doubt that a speedometer is going to be harmed by any light lubricant you throw at it. The most expensive oil is generally vacuum pump or compressor oil but it may be a bit above the light oil viscosity.
 
Bates, the best way to test the speedo is to remove the cable.

Then hook up a drill directly to the speedo and put the drill in REVERSE, and start slowly and at the same time watch and listen to the speedo gauge. This test will eliminate any noise from the cable.
 
The drill test is very useful. If you put a new cable in your Model A, take the old cable and cut off the last 2” to save the ends from the old cable. Chuck them up in the drill to spin your speedometer.
 
I generally use what the manufacturers call out on flex drive cables and service them on a reasonable time schedule. Some use dry graphite and others use white lithium like lubriplate. The key thing on the model A speedometer is to make sure the head drive turns freely. If it's stiff then the cable will let you know about it.
 
The Washington coast tribes are preparing for a whale hunt ———-I’ll see if I can get some blubber from the catch.
 
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