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Re: RPM and 'actual' speed

To: randallyoung@earthlink.net, triumphs@autox.team.net
Subject: Re: RPM and 'actual' speed
From: Herald948@aol.com
Date: Fri, 16 Jun 2000 21:07:14 EDT
In a message dated 6/16/00 7:29:11 PM EST, randallyoung@earthlink.net writes:

> Oops !
>  In re-reading my previous reply, I see that I've used 'rpm' to mean 
>  revolutions per mile, instead of the more customary revolutions per minute.
>  
>  To get the conversion factor between your tach reading (rpm in hundreds) 
>  and miles per hour....

Actually, it's probably easier yet just to look in almost any book on 
Triumphs to find that an "original" (original size tires, non-OD 3.7:1 diff. 
ratio, etc.) TR4 would yield around 20 mph per 1000 rpm in top gear, or about 
25+ mph for OD top and the optional 4.1:1 diff. Given the accuracy of a 
38-year-old tach along with tires probably a slightly different size than the 
original, I suspect that this rule of thumb is close enough for anything 
except a solid defense in traffic court. ;-)

--Andy Mace

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