Thanks for the detailed input.
Are you sure about the change date for the od, I'm quite sure that the 74
already had aJ type which makes it not a few TR's but quite a number,
coincidently I do have a 74, I have to have a look at what od is fitted.
AFAIK the speedo drive refers to a PI diff ratio, in which case you are
right in saying that the ratio is somewhat out for a carb car. I did indeed
notice the difference in the speedo drive cable clamp.
Gernot
> ----------
> From: Terry O'Bierne E.S.P.[SMTP:esp@hypermax.net.au]
> Sent: Friday, December 04, 1998 10:05 AM
> To: triumphs@autox.team.net
> Cc: gernot.vonhoegen@stir.ac.uk
> Subject: 2500 vs Tr g'box
>
> The 2500 saloon range uses a A type o/d till 1974 then a J type
>
> The TR did not change to J type till about 1975
>
> The 2 o/d units do not interchange as the gearbox mainshaft is
> quite different
>
> Assuming you have either type, the TR has a unique speed drive
> ratio. In the A type o/d, the gear is ground into the rear annulus
> output shaft and the TR only shares this with a few Rovers. It is not
> readily changeable. The 2500 box has a quite different speedo gearing
> and no amount of buggering around
> will get a sedan o/d unit to read the speedo properly in any TR.
>
> The rear drive flange on the TR uses a different bolt spacing than a
> sedan. The TR & Stag both use the same bolt spacing as the rear 1/2
> shafts ona TR5-6
>
> The rear mounting (x member) is also unique on TR with an A type
> o/d. The rear case is quite different
>
> Each model had unique overdrive setting pressures but that frankly is of
> no significance and will not stp a change over
>
> In summary, apart from the few TR's with J tyoe o/d, its simply not
> worth trying to fit a sedan unit to a TR
>
> Terry
>
>
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