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RE: [TR] Differential Identification TR4

To: "Randall" <tr3driver@ca.rr.com>, "Triumph Digest List"
Subject: RE: [TR] Differential Identification TR4
From: "Michael Andrews" <mandrews53@earthlink.net>
Date: Fri, 24 Nov 2006 19:12:05 -0800
The 3.7 gears have a smear of seafoam( light) green paint on the pumpkin
cover to indicate the gearing. Of course with partsgetting changed from car
to car, it maynot be there anymore. I don't know what color they used on
the 4.1 gears, Mike Andrews TR2inLA


> [Original Message]
> From: Randall <tr3driver@ca.rr.com>
> To: Triumph Digest List <triumphs@autox.team.net>
> Date: 11/22/2006 6:35:57 PM
> Subject: RE: [TR] Differential Identification TR4
>
> >     Apart from doing the rotation comparison test in Williams 
> > 'Restoring the 
> > TR4' book or pulling the rear cover off and counting the 
> > teeth on the crown 
> > wheel, is there any other simple way?
>
> As old as these cars are, I would say those are the only reliable ways. 
The
> gear sets interchange, so what it started out with is no indication of
what
> it has today.
>
> However, the calibration number on your speedo will give you some
indication
> as to what the car left the factory with ... assuming of course the speedo
> hasn't been changed.  The calibration number is a 4-digit number with no
> letters, which ISTR is printed below the odometer (or was that the trip
> meter ?).  For a 3.7 diff, it should be around 1150; for a 4.1 it will be
> more like 1300.
>
> Since they were (are) greatly prized by racers, there are very few 4.1
gear
> sets running around on the street today.  For example, judging by the
> calibration number, TS39781LO (a TR3A) left the factory with 4.1 gears. 
But
> it had 3.7s by the time I got it, in 1984.
>
> Randall


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