Speedometer bouncing?

[Guest Oldsman]

I have a '65 Starfire with a bouncing speedometer issue. While driving 20mph, it bounces to 40. While driving 40mph it bounces to 70. Driving at 60mph it disappears completely. I've add a dozen drops of trans fluid to the cable connections at the cruise control unit and it seems to bounce less, but only for a short while. I don't drive the car very much, and wonder if the cables have just dried out.

Any info appreciated.

Thanks!

[rocketraider]

They could need to be completely lubed from one end to other. My guess is that the speedometer head itself needs lubricating, or the cruise control regulator may need some. Is it the original electric motor driven cruise?

Speedometer magnets may have gotten weak too. A good speedometer shop can clean, oil and remagnetize the speedometer to work perfectly. 65-66 speedometer is not difficult to remove once you get the A/C ducts out of the way, just kinda close quarters. Disconnect the cable and wiring plug, remove two screws and it's out.

Here's a short tech session on how speedometers work. It's actually a small induction generator.

The cable drives a small two-pole magnet inside a small cage. The spinning magnets induce the cage to turn, and the cage is what drives the pointer. There are springs on the pointer that resist the turning of the cage. The faster the magnet spins the farther the cage turns within the limits the resistor spring puts on it.

[Guest Oldsman]

Glenn,

Yes, the cruise control is the factory installed electric unit.

Thanks for the info!

JEK

[franks 66 starfire]

check the front left wheel pull the greese cap off and make sure the cable is not restricted

i have a 66 starfire and had the same problems and i replaced the cap and it is working just fine now on the 66 olds the cable is connected to the left front wheel but mine did not have cruise control