Christopher McCann wrote:
In my 76 240D, the speedometer reads 10% high,
regardless of the speed (according to my GPS). The
trip meter (didn't pay attention to the odometer) was
accurate to .1 miles over a 12.2 mile commute.
HOW IS THIS POSSIBLE?
The speedometer needle is positioned to a point a centimeter or two
counterclockwise from the lower post/stop when the speedometer is
initially assembled and calibrated. The precise location is specific to
that speedometer (it's usually about the distance that is roughly equal
to 10 mph on the scale). Then the needle is pulled up and lifted over
the post/stop and released. It settles back against the stop. I have
watched VDO technicians do this - sometimes having to do it several
times before the speedometer is within tolerance.
This setting of the speedometer needle has NOTHING to do with the
accuracy of the odometer - which is absolutely fixed by the combined
gear ratios of the speedometer mechanism, the transmission takeoff, the
differential and the tire size. This is NOT adjustable (you would need
to change gears to make any adjustment).
Marshall
--
Marshall Booth Ph.D.
Ass't Prof. (ret.)
Univ of Pittsburgh School of Medicine
Department of Pharmacology 1300 BST
Pittsburgh PA 15261 USA
[EMAIL PROTECTED]
