Allen,
Right on.. But if the spinning magnet looses strenght hence coupling
between the plates, the speedo will begin to slowly read low. It also
won't read low one day then correct then next, or vise versa. Now if one
of the mechanical bits in the speedo where to go south, bearing, spring,
etc. then it would suddenly read bad, but I think I would be a continuos
thing, not come and go ( could be wrong...). I lean toward an electrical
connection problem with the tach. in this case, because I have a very
simular problem with one of my cars that I'm sure is electrical ( well,
as sure as anything else when it comes to this sort of stuff.....).
Harlan.
-----Original Message-----
From: Ajhsys@aol.com <Ajhsys@aol.com>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: Thursday, September 17, 1998 11:51 AM
Subject: RPMs
>>Date: Wed, 16 Sep 1998 19:19:11 -0500
>>From: "Harlan Jillson" <hjillson@argolink.net>
>>Subject: Re: RPMs
>
>>The speedometer on the other hand is a mechanically
>>driven device running off of the gearing in the transmission. The speedo
>>should read correctly if there isn't a problem with the drive cable, lack
>>of lubrication, frayed wire in the cable etc. that would cause the cable
>>to bind in its rotation, which would usually cause the speedo to 'jump'
>>around.
>
>After you get past the mechanical drive of the speedo, the cable ends with
a
>spinning magnet that attracts the cup on the back of the needle to indicate
>the correct speed. If the needle and magnet aren't aligned correctly, or
if,
>after many years of high speed fun, the magnet starts to lose its strength,
>you will get false readings from a speedo, altho usually low readings. If
the
>speedo were completely mechanical with the cable driving the needle,
wouldn't
>the needle just spinnnnnnnnnnn!?! (FWIW)
>
>Allen Hefner
>Honesty is the best politics. (Stan Laurel)
>
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