Re: [alfa] Speedometer Calibration

["Gwynne W. Spencer" <gwynnes1@xxxxxxxxxxx>]

Lots of speedometer shops can adjust the speed reading if the unit is the 
old fashioned mechanical type, and some of the electronic units can be 
adjusted also. Try to find a speedometer shop - if there is no local one, 
they often advertise in enthusiast magazines.
BUT, if it is off despite stock wheels and tires, you may have to provide 
the shop with error data like you took, as they usually just set them up to 
factory specs - ie: speedo should read XX MPH at some specified input RPM 
to the speedo head. There used to be places where you could buy a 
correction gear box for speedometers - tell them what change you are 
looking for. Of course, that also changes the distance recorded as well as 
the speed shown.

Gwynne Spencer

At 12:53 AM 3/24/2004 -0500, you wrote:
>Dear Alfisti:
>As Sir Smokey so rudely brought to my attention, my speedometer is, ah,
>misleading.
>I knew I was over the limit, but the number from his radar was way higher than
>I thought I was going.
>So I got out my handheld GPS and did some experimenting:
>At indicated 55mph, Mr GPS says the car is doing 64mph
>At  indicated 60, actual speed is 71mph
>And at indicated 65, 79 mph - which agrees with Sir Smokey's radar.
>
>I'll use this to try to get charges reduced to what the speedometer said, but
>have any of you an idea why the speedometer is so far off?
>The car is an '87 Spyder Quad, with stock rims (6J x 15" H2) and Owner's
>Manual spec'ed tire size: 195/60 R15.
>And what can I do to get it fixed?  Is there a gear in a sending unit that can
>be replaced, or an adjustment screw somewhere?
>Dave Martin
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