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Why does my speedometer keep bouncing back and forth?

Why does my speedometer keep bouncing back and forth?

The cable spins and the faster it spins the more it can fluctuate. The cable spins the gear for the miles and a magnet for the speed. There is a spring on the back (inside) that puts tension on the the spinning magnet to keep the speed steady.

Where is the clock spring on a speedometer?

The “clock spring” on the front speed cup ensures that the speed cup’s resting position is at the “zero index” point on the speedometer’s face plate . . . no more, no less, although it’s possible effect upon speed calibration is compensated for by the magnetic force of the rear speed cup’s bar magnet, typically.

What kind of noise does a speedometer make?

This noise should be similar to a scraping and ringing noise when it momentarily happens with each revolution of the speedometer cable. Each “touch” can make the speedometer needle jump.

How can I Make my odometer go back up?

You can MAKE it do this, by holding down the odometer reset button with the car turned off, until the self-test starts. The needles will move, and all lights and LEDs will light up. It takes about 20 seconds.

How much does it cost to rebuild a speedometer?

Begin by cleaning and lubricating the cable, but you probably have a combination of issues. On average, a speedometer rebuild runs $150. If you can purchase a guaranteed speedo for less than that by all means do so. Just keep in mind that the old lubricants, even in an NOS unit, dry up over time. Sign up for a new account in our community.

What should the temperature be on a certified speedometer?

On “certified” speedometers (for law enforcement use vehicles), their calibration is specified to be + or – 1mph over the full speed range, IF the interior temperature is within a normal temperature range. It could well be a special clock spring which makes this close-calibration possible, as well as tighter quality control.

Why does the needle bounce on the speedometer?

That should cure it… The speedo cable for those old cars is like a spring. If it hangs up somewhere due to poor lubrication when it releases there is pent up energy so it “over releases” and creates the needle bounce you see on the speedo. This is first a lubrication issue.

What to do if your speedometer keeps jumping?

Pull out the inner cable, clean and inspect it, coat it with light grease, or M/C cable lube and put it back together. That should cure it… The speedo cable for those old cars is like a spring.

This noise should be similar to a scraping and ringing noise when it momentarily happens with each revolution of the speedometer cable. Each “touch” can make the speedometer needle jump.

Why is the speedometer bouncing on my Caprice?

The lighting, background building, the feeling of the 70’s and of course, the beautiful looking ’78 Caprice. More sharing options… In some cases it can be a build-up of dust, grime or dried out grease on the moving parts inside the speedometer. This is just an example and not your actual speedometer head. Yours will be similar.

What does a zap gun do to a speedometer?

At the speedometer shop, to effect such calibrations, it’s a cut and try method with a “zap gun” (for those who were around in the earlier days of color television, you might remember the “degause” treatment of the picture tubes . . . the “zap gun” is similar, as it affects the ultimate magnetism of the rear speed cup’s magnet.

The cable spins and the faster it spins the more it can fluctuate. The cable spins the gear for the miles and a magnet for the speed. There is a spring on the back (inside) that puts tension on the the spinning magnet to keep the speed steady.

The “clock spring” on the front speed cup ensures that the speed cup’s resting position is at the “zero index” point on the speedometer’s face plate . . . no more, no less, although it’s possible effect upon speed calibration is compensated for by the magnetic force of the rear speed cup’s bar magnet, typically.

At the speedometer shop, to effect such calibrations, it’s a cut and try method with a “zap gun” (for those who were around in the earlier days of color television, you might remember the “degause” treatment of the picture tubes . . . the “zap gun” is similar, as it affects the ultimate magnetism of the rear speed cup’s magnet.

What to do if speedometer needle jumps up and down?

Reach around behind the speedometer or remove the instrument cluster to gain access and disconnect the speedometer cable from the speedometer. Pull out the inner cable, clean and inspect it, coat it with light grease, or M/C cable lube and put it back together. That should cure it… The speedo cable for those old cars is like a spring.

How can I remove the speedometer cable from my car?

Reach around behind the speedometer or remove the instrument cluster to gain access and disconnect the speedometer cable from the speedometer. Pull out the inner cable, clean and inspect it, coat it with light grease, or M/C cable lube and put it back together.

What should I do if my speedometer needle shoots up?

Although it usually takes a mechanic to be able to fix this problem, you can do some simple troubleshooting for the speedometer needle so you have an idea of possible causes and what to expect. Scenario: you are driving at normal speed when suddenly your speedometer needle shoots up by 10, 20, or even 40 miles an hour.

Why is the speed sensor on my car not working?

Possible problems: the speed sensor on the passenger axle may need to be replaced. The speedometer cable may be damaged or broken. If the vehicle has cruise control, the cruise control transducer could be faulty and a new one should put in its place.

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Ruth Doyle