Miata Mailing List: February 1997, Message #15
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   From: (none)

Subject: RE: Tach gauge and other gauges

   Date: (none)







I think the most accurate way to calibrate a speedometer would be using the

tach.  Get your tach calibrated (that one's easy!) or use an external,

--> Where can one get an external tach, how much would it cost, and how does 

it hook into the engine?



 then

check your speed against the revs.

-->I noticed the guage faces said 1024 equals 20MPH in 5th gear, which is true 

as my car always did about 3K at 60MPH.



  You'll have to take tire wear into

effect, though - I've seen almost 10% difference in odometer readings

between old and new tires.  That can be checked by measuring the tread depth

and comparing to new.  There's a solid connection between the engine and the

wheels, so you've cut out a lot of variables, and I think it's easier than

using a GPS!

-->Actually, I know my tach and speedo are back in the right place because of 

the fifth gear test...it all checked out just like before the new faces.

Matt