OK boys and girls... Grinding a little bit of length off the end of the cable might be a simple cure but... This spiral wound cable, wound opposite direction of applied forces, simply cannot "grow" in length.
The truth is, grease hardened with metallic wear debris packs the instruments input port. Same push on the instrument internals occurs. Harbor Freight has a 4 dollar set of hobby or jewelers files and there is a very small square file included. That file and some parts cleaner can clean and deburr the inside of that square drive and that end of the cable. We know we cant orient the square faces exactly the same as was before it was removed.
I never serviced 1 failed speedometer that wasn't damaged by forces applied at the input shaft.
About the worst thing one can do is replace a broken speedometer cable without cleaning the instrument input. It's like writing a death sentence for the instrument.
Even through the shaft bore assembly is nearly 2 inches long, It wont last forever. Nothing mechanical lasts forever.
Here's a tip, something to look for. We often see speedometers listed for sale here. When photographed, the instrument was leaning/resting on the end of the input shaft. OEM lengthwise travel clearance there was only .005 . This would not effect needle position. If the instrument is like new, one could lift and rest it in this position over and over again and never move the needle away from zero. So... Look at the pic. If the needle is standing at 5 mph, that instrument is well worn. At 7 mph or better, I won't buy it. That much linear wear suggests the bore clearance of .002 has increased also. Excessive bore wear is the worst condition since it allows rotating parts to collide. Result is severe needle bounce and eventual catastrophic failure.
