mgs
[Top] [All Lists]

Re: odometer symptoms

To: gardner@lwcomm.com
Subject: Re: odometer symptoms
From: barneymg@juno.com (Barney Gaylord)
Date: Wed, 20 Aug 1997 07:08:57 EDT
On Wed, 20 Aug 1997 01:25:15 +0000 "Scott Gardner" <gardner@lwcomm.com>
writes:

>..... Also, my tenths' wheel doesn't move smoothly, like a sweep-second
hand.  It actually moves a small increment at a time, like a second hand
"ticking".  Is this normal, or is it wearing out, as well?  It moves five
small "ticks" for every tenth of a mile.

I assume you're talking about MGB here, and I wouldn't bet on it being
exactly five ticks per tenth mile.  The incremental motion of the tenths
wheel is normal.  The tenths wheel of the odometer is driven by a ratchet
pawl pushing on a toothed wheel.  The number of teeth used on that wheel
is part of the factor to get the odo to come out right for the final
drive ratio and tire size.

As I recall, the odometer in my MGA 1500 has 58 teeth on the ratchet
wheel.  So, it sees 6 ticks for every 1/10 mile, except that twice per
mile it only uses 5 ticks to come out even.  All that irregular motion
makes it real tough to get an accurate reading during a TSD rally.

Also, as a matter of curiosity, that ratchet pawl continues to trace out
a similar motion when the car is moving in reverse.  So, the odometer
cannot be made to run backwards by driving backwards.  I would think the
odometer would continue to run forwards when the car is going backwards,
but as I recall, it doesn't, it just stops turning.  I seem to have tried
this in a rally once.

Barney Gaylord
1958 MGA with an attitude

<Prev in Thread] Current Thread [Next in Thread>