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Re: TR-4A - 4.28 rear end; what gives?

To: triumphs@autox.team.net
Subject: Re: TR-4A - 4.28 rear end; what gives?
From: Keith A Edwards <kedwards@norfolk.infi.net>
Date: Thu, 04 Mar 1999 07:53:04 -0500
Cc: John Cowan <jfcowan@earthlink.net>
Organization: Suffolk
References: <3.0.5.32.19990304004918.01826630@earthlink.net>
Yes, there was an optional 4.3 rear axle ratio available from Triumph
for "speed" use.  I have that ratio in my former SCCA E/P TR3B.  There
was another numerically higher ratio, as well.  4.55 perhaps.

I really like the 4.3 ratio for autocross.  For track use, the general
theory is to select the ratio that will put you at redline in high gear
at the end of the longest straight.  4.3 will work well for _some_
tracks (but don't ask me which ones).

Keith Edwards
Suffolk, VA
kedwards@norfolk.infi.net
http://members.tripod.com/~Keith_Edwards/
2 TR3Bs (one former SCCA race car)
2 TR4As "live" axles
1 Austin-Healey 100
1 Austin Princess Vanden Plas limo


John Cowan wrote:
> 
>     I measured the ratio of the differential on my '66 solid axle TR-4A
> several times and it fell between 4.26 and 4.28 to 1.  This result was
> unexptected, but is borne out by the fact that the car revs up and tops out
> especially quickly.  I've heard rumor of a special 4.3 to 1 rear end, which
> if accurate could explain what I have (the disrepancy being experimental
> error, although I was pretty careful).
>     Is there a 4.27 or 4.3 to 1 differential available?  If so, it would
> seem suitable for Autocross.  Would it also be suitable for road racing?
>     Thanks.
> John Cowan
> 
> Visit - In Their Own Words Website - an on-line non-commercial publishing
> experiment, plus movie reviews, articles and Left/Progressive links at:
>                            http://home.earthlink.net/~jfcowan

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