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Using Tachs as Speedos

To: Scions of Lucas <british-cars@autox.team.net>
Subject: Using Tachs as Speedos
From: Greg Meboe <meboe@wsuaix.csc.wsu.edu>
Date: Thu, 29 Sep 1994 17:01:51 -31702 (PDT)
> Sandro Menzel writes >
> 
> >On my '66 Midget, my calculations had me going 15 + the tach's value
> >when in fourth gear. So, traveling at 5000 rpm = 65 mph, give or take a
> >couple mph.

I think some who read that may get confused.  the relationship between 
the tach and road speed will involve multiplication, not addition.  For 
example, a tachometer could read 1/2, 1/3, 23/64ths or some other such 
obtainable fraction of road speed in any given gear.  This relation will 
hold throughout the rpm range in that gear, (tyre expansion and guage 
inaccuracies notwithstanding).  
        Since I drive a Triumph, it stands to reason that my speedometer 
continues to break faster than I can fix it, so the tach frequently 
doubles as speedo.  Maybe it was intended this way, I mean you can get 
both engine and speed data from one gauge. Neat huh.


   Greg "gosh officer, I was only doing 7" Meboe   meboe@wsuaix.csc.wsu.edu




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