[GTOh!]

I could be wrong, but I’m quite sure that all of a sudden and without doing anything to the car but drive it, it seems my speedometer is reading approximately 10mph higher than the last time I had the car out and 10mph higher than actual speed.

Ideas?

Thanks in advance for your thoughts!

[Peter Serio]

You could be right at the end of it's service life. No cable driven speedometer will last for over 1/2 a century. At some point it will lock up. typically this happens when you are on the freeway. Given the RPM on the cable, for example at 60 MPH on the dial, the cable is in rotation at 1,000 RPM.

[GTOh!]

Thanks, Peter. Could/would reaching end of service life actually cause the needle to read higher by a consistent 10mph? Whether I'm traveling at 30 mph, 45 mph or another speed, it's reading 10 mph over actual. FWIW, It has been wavering (not a steady readout) on occasion ever since I got the car. I did receive a new speedo cable with the car.

Maybe the PO had an inkling that it would soon be needed? put approximately 600 miles on it since buying it last July.

[tstroud]

It’s probably the speedometer cable getting ready to break.
They do need replaced occasionally.


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[Peter Serio]

The wavering could be a sign that the cable is going bad. I would replace the cable and casing assembly and then road test.

If the pointer is still wavering or your speedometer is reading higher MPH than true the only other thing it could be is the bushing inside of the speedometer is worn and the old oil inside of that bushing has long since turned to glue. Over time the original oil breaks down and once all of the slippery parts of it are gone what's left is more like glue or tar.

What you DON'T want to happen is for the speedometer to lock up. The damage caused when that happens is severe!

[GTOh!]

Originally Posted by Peter Serio

The wavering could be a sign that the cable is going bad. I would replace the cable and casing assembly and then road test.

If the pointer is still wavering or your speedometer is reading higher MPH than true the only other thing it could be is the bushing inside of the speedometer is worn and the old oil inside of that bushing has long since turned to glue. Over time the original oil breaks down and once all of the slippery parts of it are gone what's left is more like glue or tar.

What you DON'T want to happen is for the speedometer to lock up. The damage caused when that happens is severe!

Ugh. Thanks, Peter. I appreciate that warning.

I have a new cable. It came with the car. I’ve replaced cables on my Corvette and other cars, so I’m familiar with that. What kind of job might it be to replace the speedo bushing? Sadly, I just had the whole dash out and part, replacing all the instrument panel bulbs and the gauge lenses.

Thanks again.

[gomowgto]

I had the same thing happen to mine probably 10 or 12 years ago. Speed didn't change, but he needle kept bouncing all over when I drove it. I sent it to Pete, and he rebuilt it, replaced that bushing, resilkscreened all the speedo numbers and marking, and repainted the interior workings in the proper reflective paint like the factory.
His work was flawless and as good or better than new. It's still working as good as it was the day I reinstalled it. I would recommend Pete to anyone. Thanks for the great job Pete.