ckr wrote:
>
> Thomas J Pokrefke wrote:
> >
> <SNIP>
> >
> > While I am at it, when I drive, the needle on the speedometer fluctuates
> > over a 20 mph range. While I have the speedo out and on my desk, is
> > there any area I could clean/oil to have a 'normal' speedometer?
> >
> > Thanks in advance,
> > Thomas James Pokrefke, III
> > 1970 MGB
> > thomas_pokrefke@juno.com
> > http://ocean.st.usm.edu/~pokrefke
>
> Thomas ... I'll be as interested as you in the answer to this. My speedo
> does the same thing.
>
> Corey
> 75 MGB 'Rags'
Tom and Corey and list: This is a classic case of "tired cable" The
inner speedo cable becomes softer and more flexible as it ages and
wears. The odometer mechanism of the speedo works on a ratchet principle
and has a little pawl that climbs up a ramp on a gear. The extra effort
required to climb up this slope "winds up" the cable a little and so it
slows down. As the pawl drops off the tooth, the cable unwinds and
speeds up. This small speed variation is enough to cause the needle
swings which can be as much as 50 MPH! Quite often replacing the cable
cures the whole problem, although sometimes an older dried out speedo
may need cleaning and lubrication as well. Jarl
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