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Re: Does the OD tranny require a shorter drive shaft?

Subject: Re: Does the OD tranny require a shorter drive shaft?
From: Florrie & Allen Bachelder <>
Date: Tue, 21 Dec 1999 16:16:47 -0400
In my experience, the 1000 and 1280 speedos (or at least their faces!) are
not interchangeable as the drive gears were different.  But these
differences were not related to the presence or absence of overdrive.  I
had occasion to swap out the original O/D tranny in my '73 GT with one from
a '76 B parts car.  Both O/D trannies, but I had to swap speedos also.  In
my case, the solution was simple - use the speedo from the '76 donor car.
But it is useful to know one can just swap out the faces... WAIT A Minute -
it can't be that simple.  Changing the face will not recalibrate the
odometer!  There must be an internal difference.


BTW, I now have occasion to swap back to the '73 O/D tranny... Amongst it's
other faults (due to rebuilder's oversight), unlike a proper '76 O/D, this
one shifted into O/D in ANY gear.  ' Was quite perturbed one day as I wound
it out in 2nd and it upshifted at about 35 mph.  The lockout switch was
faulty.  ' Would have cut a hole in the tunnel to replace it but the tranny
has other problems and has to come out anyway.

>From: David Councill <>
>This would seem logical. But I thought the internal gearing was different
>on the speedos originally. Even if so, a recalibrated face would be an
>easier fix. When I first changed my o/d, I just put a couple of small
>pieces of scotch tape on the side and then made marks for 60 and 70 mph
>which I determined by a long highway drive, timing the intervals between
>mileage markers.
>67 BGT
>71 BGT
>At 12:59 PM 12/21/99 -0500, Kai M. Radicke wrote:
>>The speedometer does not need to be changed, I repeat... the speedometer
>>does not need to be changed.  The only difference is the face of the two
>>speedometer, the internals are all the same.  It is a simple swap... and
>>much less costly than purchasing a new or used unit.  Not to mention that if
>>you have a sad looking speedometer, a new face can really bring the life
>>back to it!
>>Call Nisonger /
>>They'll have the face in stock.
>>Again this is another "ask me how I know" learning experiences ;-)
>>Kai M. Radicke --
>>'74 Triumph TR6 --
>> > And the speedometer will need replaced, I think the 1280
>> > is the o/d and the 1000 is the regular. Or maybe its the
>> > other way around. My BGTs are home right now, out of
>> > the snow, so I can't verify that part. But its one or the other.
>> >
>> > David
>> >
>> > 67 BGT   w O/D
>> > 71 BGT   w O/D

         Allen H. Bachelder  =iii=<
         Sinking Creek Home for Wayward MGs
        49 YT, 57 ZB, 58 ZB, 65 B, 67 BGT, 73 B, 73BGT, 76 B, &...
         New Castle, VA 24127

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