[TR] TR3 gearbox

[Greg Lemon]

The TR6 used both the A-type (early) and J type (late) overdrive.  The TR3
should be A-type.

I would not want to use a non-synchro first gear box on a TR6, seems like a
downgrade.

If you don't take the car on trips of any length on the freeway you
probably don't need overdrive but you might still want it, even if you
don't because it is a fun option.

I think what others are saying is you can install the A-type from the TR3
on the TR6 box (you may need a new main shaft, not sure if TR3 and TR6 are
the same, but you use a different main shaft with O/D, so I don't know if
you could use the TR3 overdrive shaft, the more I think about it probably
not, or you would need to get a TR6 main shaft for O/D).

Anyway to put in a new main shaft you need to rebuild the transmission,
take it all apart and put it back together.  I have done everything on
these cars, engine, suspension, electrics, etc., transmission is the only
one I tried twice and gave up on, read all the books, measured thrice,
installed once, still had a dodgy gearbox when done (second gear stopped
engaging).  Some guys say they took one apart and put it back together in
an afternoon with no manual over a couple beers with and adjustable spanner
and a hammer and rod to drive bearings in and out and it ran great for
years,so maybe I am an idiot and your mileage may vary, but transmission
rebuilds are tricky in my opinion.

Anyway, the A type can be mated to the TR6 box, but it is a bit of a chore,
you can do yourself or pay somebody,you will also need to fabricate new
transmission mounts. (fairly easy, there are even instructions out there
somewhere to do it with angle iron and no welding), and your speed drive
will now be geared wrong I think.

This is my long winded way of saying I would sell the 3 box and 0/D and see
if I could get a TR6 box and O/D if it were me.  Which seemed like it was
your original inclination.

Greg Lemon
TR250







On Wed, Oct 25, 2023, 3:41 PM dave northrup <dave at ranteer.com> wrote:

> I recently acquired a car with a TR3 overdrive that probably needs to be
> rebuilt.  I was wondering – is the non synchro first gear really an issue?
>
>
>
> The car has a TR4 engine anyway and I have a nice TR6 tranny (non
> overdrive).  We do not care about originality; rather we are going for
> performance with a mild cam, 89 mm pistons, lightened flywheel, etc
>
>
>
> Am trying to decide if I should sell the TR3 tran to fund the upgrade on
> the TR6 tran
>
>
>
> both the engine and tran were out of the car; its going to need some work
> anyway
> ** triumphs at autox.team.net **
>
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