Speedometer is 15 MPH fast

spdway1

spdway1

Well-known member
My 28 Oval speedometer is close to 15 MPH FAST! :eek: What would be the culprit to this?:confused: The speedometer or the gear under the car? :cool:

Thank you for your help.
 
To determine whether the speedometer gears are correct, go for a drive over a known distance (or measure the distance you cover with a GPS) and compare the odometer with that distance. If they agree, the gears are right. If they are out, you almost certainly have the wrong ones.
Most of these old instruments read slow but after all these years, who knows. There are a number of guys about who can overhaul them, especially he oval face ones.
 
Most likely it is the speedometer vs the turtle gear. Is it 15mph off at 10 and 20 and 40 and 60 mph?

Just do as syncho mentioned against gps.
 
Synchro has the correct answer as to how to test the gear ratio. If you don't have a known distance to travel, you can use a GPS to measure the distance. If the gear ratio is correct then you can take the speedometer apart and adjust the spring tension. There is a little arm on the spring that is adjustable. Making the spring shorter will increase the tension and reduce the indicated speed. Don't do this unless you are comfortable working with delicate parts like the innards of a mechanical clock. Otherwise ship the speedometer off to someone who can fix it.
 
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