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Speedo revs/mile

To: alpines@autox.team.net, tigers@autox.team.net
Subject: Speedo revs/mile
From: Jay_Laifman@countrywide.com
Date: Mon, 16 Oct 2000 09:24:28 -0700
Over the weekend, I marked off 52' 9.5" and counted the number of
revolutions of my speedo cable.  It was exactly as an article in the SAOC
handbook says - 1440 rev/mi.  This is with a 3:89, SV OD tranny and
Michelin 165-13 XZX tires.

In case anyone wants details on how I did it:

First I parked my car in the street and put a large square trash can up
against my front bumper.  I marked the ground right where the bottom of the
can met the ground.  I measured 52'9.5" away.  Made a mark, and moved the
trash can to that spot (then rechecked a few times).

Then, I disconnected my speedo cable, and let it hang down.  I cut out a
little pointer out of thin cardboard, cut a small "X" in it and pushed it
on the end of the cable (sort of looks like a little Washington's Monument,
1.5" long 0.5" wide with a point at one end).  I then took an index card,
punched a hole in the center, slightly larger than the cable.  I slid it on
the cable (so from top down: hanging cable housing, pointer, flat card, end
of cable.  I then hung the flat card by dropping tape from the cable
housing a few inches up and down to the edges of the card.  This way, the
card was flat, held in place (just below the pointer, with no binding), and
the pointer would spin on top of it.  (if this doesn't make sense and
someone wants more detail, let me know).

I marked on the card where the pointer was pointing and drove to the
garbage can, 1/100th of a mile away.  When I reached 14 revolutions, I
stopped the car, and then slowly pushed the car until just touching the
garbage can again.

Then, I marked the card where the pointer was.

I did this 3 times, one time stopping about .125" from the can.  Each time
the results were almost identical.

So, off to the speedo shop it goes.

Jay


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