[T3] Recalibrate speedometer

[Mike Fritz]

Okay, it sounds like the deviation is linear. This means it's not an 
issue of wheel size, or gearing. If it were, the symptoms would be 
exponential. (If I'm getting my math terms right!)

That is, it would be off a PERCENTAGE not a fixed deviation. Having 
never experienced this problem before, how I would approach this repair 
is to carefully pull the needle off the shaft in the speedometer and 
reposition it correctly. How is this done? I have no clue!

Thinking aloud, I suppose I would remove the speedometer and have a 
friend drive the car at a fixed speed while you hold the connected 
speedometer in your hand. Remove the needle and reposition it that way.

Or, you could remove the speedometer and cable. With the cable attached 
to the speedometer, use a drill to get the speedometer going at a 
certain speed, say 20 MPH. Tape the trigger on that drill so it stays at 
that speed. Then, remove the needle and reposition.

That's just me thinking aloud, no idea if any of that is practical, or 
even the best way. Keep up posted on how you proceed!

Regards,
Mike

On 5/7/2015 1:24 PM, Jacob Adam Schroeder wrote:
> Yes.  So my needle does not move off at all until I'm going about 10 mph.
> When I'm driving at 30 mph (according to my smartphone's GPS), the
> speedometer reads 20 mph.  When I'm driving at 70 mph, the speedometer
> reads 60.  I will confirm again on my drive home from work, but it appears
> that my speedometer registers 10 mph under regardless of which speed I
> drive.
>
> I have owned this car for about 20 years and I have never taken this apart,
> whether the PO did is another question.
>
>
> On Thu, May 7, 2015 at 10:25 AM, Mike Fritz <mwfritz at lycos.com> wrote:
>
>> On 5/7/2015 9:43 AM, Jacob Adam Schroeder wrote:
>>
>>> I have a 1972 Squareback and my speedometer is consistently about 10 mph
>>> slow.  Is this just a case of my speedometer needing to be recalibrated?
>>> Is this something that is easy to do or are specialized tools required?
>>> Thanks!
>>>
>>> Jacob
>>>
>> I suppose that depends. When you say "consistently about 10mph slow", do
>> you mean at 10 MPH it's registering 0 MPH? At 30 MPH, it's registering 20
>> MPH? I guess my question is: Is the deviation linear?
>>
>> Regards,
>> Mike
>>
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