You might remove the speedometer (4 nuts hold it plus hi-beam bulb and night illumination bulbs) and see if you can use some naphtha to free up the wheel where the cable connects...this wheel is brass and is about 3/8 inch in diameter. Usually there will be dried old grease there and this could be causing the problem you described. See if the wheel (you can turn it with two fingers) back there turns easily and see if you feel any resistance or scratchy areas. It sounds to me like your speedo unit needs lubrication. I have one for sale here. Another fellow has asked about buying it, but I haven't heard back from him yet. I don't know where you're located but pickups from the late 40s to the early 70s used basically the same speedo guts. Below is a look at the wheel you need to turn...
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Just below the bolt shown in the above picture there is usually a small cup soft plug. If you pry it out with a small sharp corner screw driver you will find a felt wick. Add a few drops of light oil to the felt. This most likely will cure it.
Yes, it is Dave...it is the one I had offered for sale a few weeks ago (which one fellow has told me he wants). Apologize for any confusion. It came from a 1969 pickup but like all these (up through around 1973 or 74) it fits right in and it looks like the plug was up inside by that time. Sorry...I didn't have one of the earlier ones handy. Now everyone can see early and later.
If you want to see something interesting, I'm still working on adapting the 1995 S-10 speedometer plus tach & vacuum gauge into the 1952 speedo unit. Take a look at the screw pattern on the back side of the electronic unit (first image) compared to the screw pattern on the old 1952 speedo (next image). Not only is the angle and orientation the same, the distance between screw centers matches...although you would need to use a washer to use the smaller diameter screws:
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
The first thing to do is pull the core out of the cable. Feed some grease to it as you feed it back through the casing. Put a little oil on the spindle in the back of the speedo. Usually that will fix it.
George
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne Super In the Gallery Forum
Maybe if you didn't drive so fast........the speedo wouldn't be screaming so loud. LOL
Craig
My '50 Chevy 3100 5 window, '62-235cu, 3:55 rear My truck ....... Respect The Rust If I'm not working on my truck, '65 m00stang or VW camper, I'm fishing with the wife or smoking Salmon.
I'd buy a new cable and see if it improves. You're located in the US. Cold weather, perhaps? My old cable would grind and bounce fro 0 MPH to pegged when it got below 10 degrees or so. I'll bet it's a sticky cable.
34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.
54 1st series 3600. Speedo screaming, and needle flipping from 0 to 90. Took cable off at speedo, no noise from cable test drive. Thanks,Dennis
The same thing started to happen to me yesterday driving my 51 3100. I think it was the freezing temp, but it didn't stop as it warmed up, just got louder and more erratics. Then it got weird: the speedo needle started spinning around very fast BACKWARDS , counter clockwise that is, and continued for maybe 20 seconds that way, then settled back to jumping around again , sometimes 20-40 sometimes 40-60. The odometer seemed to be working normally the whole time. Did I fry the spring or something? Is it terminal?
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)