Fried Speedo

[Mike in Mass]

1939 truck .Still 6 volt. .Installed electric wipers and had the toggle switch mounted in the throttle hole in the dash .Wipers suck,both go at different speeds ,no controls for that ,passenger side stopped working soon after I got it home(thankfully I was getting dizzy) ,drivers side died not too long after .All right ,,no wipers ,I can handle that ,,,,I unscrewed the toggle switch in the dash and left it hanging under the dash.. got distracted ,didn't think about it ,,,,,,Well I figure it was searching for a ground while hanging and glommed onto my speedometer cable While giving my son a ride to work .He saw a spark under the dash .It all came back to me . SO What did I screw up anhow do i fix it NO speedometer No Odometer.used to work great .sorry for the long story

[Angledrive]

Most likely you fused the outer cable to the inner cable and the inner cable broke.

[Mike in Mass]

yep , that's what it looks like ,,so what do I need ,just a new cable ? anything thing else I maybe screwed up
? Is the cable," Picup" only or will any 39 cable work .Did I screwup my turtle too . I Think I break more things on this truck than Old Age does !!!

[40cpe]

I destroyed my original cable with a torch. I had already disposed of the old cable when I replaced it. The seller offered two lengths of cables. Naturally I bought the wrong, longer, one.

[Flathead Fever]

That's strange. I'm thinking you need to run a heavy ground wire from the body to the engine. Maybe one from the engine to the frame too. If they grounded the cable to the block but did not ground the engine to the cab every electrical device on the cab could be using the speedometer cable and maybe the throttle linkage for the ground. How would you like to have your throttle linkage weld together at 60 mph!

People forget that the engine is setting on rubber mounts. The transmission rearend are hooked to leaf springs that "could" have insulated bushings. The shocks have insulated bushings. Its possible for the entire drivetrain to be insulated leaving no ground connection to the body or frame. The body could be insulated from the frame. You always need to run a ground wire from the engine to the body. You should run one to the frame. If you installed a electric fuel pump, taillights... and grounded them to the frame you would not have a good ground without a wire from the block to the frame. You can't have too many grounds.


When I was sixteen I was building a clone '65 GT-350 Shelby. I moved the battery to the trunk. Then ran a large welding cable from the positive terminal up to the starter solenoid. I ran the ground cable from the battery to the trunk's floor. I started cranking the engine and smoke started pouring off the manual choke cable in the engine compartment. Without thinking I grabbed the cable. It left little barbecue grille marks across my hand. It burned it pretty bad. The only ground that starter could find was through the choke cable, to the dash and then back to the battery in the trunk.

Later I took two AC and DC electronic classes at the local college. The instructor said, "all electrical devices run on smoke because if you let the smoke out they stop working."

[Mike in Mass]

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Thank you for the replies .I will get a new cable.

[richard crow]

next time put a fuse on the feed wire