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G3GM 1973 to 1977 A-bodys. Chevelles, Monte Carlos, El Caminos, Laguna, 442, Cutlass, Malibu, GTO, LeMans, Century, Regal, Grand Am, Grand Prix, Sprint, Gran Sport, Can Am, Hurst-olds, and other 73-77 A-bodies


speedometer

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speedometer Empty speedometer

Post by mychev123 Tue Jan 29, 2013 7:37 pm

Is there any way to calibrate the speedo on my 77 malibu? Its off by atleast 10mph.
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speedometer Empty Re: speedometer

Post by dynchel Tue Jan 29, 2013 8:19 pm

Why is it off? Has the tire size been changed? The rear gearing? I have heard it's possible to correct (or at least improve) by changing a gear in the transmission. I have never done this and have no first hand experience. If your speedometer is reading to fast a taller tire will lower the reading. The opposite is true if it's reading to slow. Good luck Leg Hump
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speedometer Empty Re: speedometer

Post by mychev123 Tue Jan 29, 2013 8:42 pm

When I got the car it had the stock tire size on it and it was off then, now it doesn't but its still off about the same. Not sure if the gears were changed before I got it.
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speedometer Empty Re: speedometer

Post by 77mali Tue Jan 29, 2013 8:54 pm

Is it a sweep style gauge or round?

I can't see how it's off if you did none of the mods that dynchel mentioned but I suppose it's possible the speedo gear has been damaged somehow or is worn out or that something is going on with the cable.
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Post by 77mali Tue Jan 29, 2013 9:03 pm

Here is a good link...get your new tire size and call these people...They sell all the parts & can walk you through what needs to be done.

http://www.partshp.com/speedometer_gears.htm#350

1-888-8771008, 6:30 to 5:00 CST, M to F
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speedometer Empty Re: speedometer

Post by bigredlaguna Wed Jan 30, 2013 12:03 am

Check your odometer to the mile markers. The speedometer cable is linked directly to the odometer. If the mileage is good, then the speedometer part may need cleaning or lubed. If the mileage is off, then adjustment via gears or tire size will correct it.

The cable drives a rotating magnet, and the needle is held back with a spring. gummed up innards may increase the resistance and cause a low reading. The spring may be weak and allow a high reading.
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Post by Brainstain Wed Jan 30, 2013 9:16 am

The little gear inside the tranny is super easy to change. It's one bolt on the driver side where the cable goes in. After that it should just slide right out.

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Post by 77mali Wed Jan 30, 2013 10:36 am

This is what it looks like (or similar if you have a TH350)- the fluid will come out of the trans when you remove it- so be ready. Very Happy

Just unbolts & is easily removed by hand as mentioned.

speedometer P1030810

Inside Tail Housing:

speedometer P1030811
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Post by mychev123 Wed Jan 30, 2013 12:37 pm

Thanks for all the info, Ill check it out!
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