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RE: TR3 tranny interchangability with TR4

To: "Triumph" <triumphs@Autox.Team.Net>
Subject: RE: TR3 tranny interchangability with TR4
Date: Wed, 29 Sep 2004 10:37:50 -0700
> I have a grinding, clonking TR4 overdrive transmission so I'm planning
> to swap in the spare supposedly rebuilt TR3-sourced transmission I have
> stashed in the garage.  I wanted to double-check; it's a straight swap,
> right?

Not really.  A TR3 gearbox is shorter than the TR4 box, and lacks
synchromesh on first gear.  The gear lever also moves farther forward on a
TR3 box, although I don't know if that's a problem on a TR4.  The levers
will interchange, but moves farther forward in 1st gear.

If it's an early (pre-TS50k) TR2-3 box, then it won't fit with your TR4
starter.

And of course your overdrive won't fit (if the TR3 box is non-OD).  The
mainshaft is different between TR3 & TR4 and also different between OD &
non-OD.  Takes a full teardown to change the mainshaft, once you source the
right one.  You'll also need to attend to the lockout switches (if you try
to keep the OD), since the TR4 top cover will not fit the TR3 box unless you
swap over the shift rods & forks.

> Anyone care to estimate the time it'll take, including clutch
> replacement, based on been-there-done-that experience? I've never done
> it, but after 5 years of daily driving I've done about everything else
> with plenty of advice from the list.

I'd allocate an entire weekend, if it's your first time.  And have a backup
plan for not being able to drive the car on Monday.

> Finally any reason not to order a
> Moss Borg & Beck clutch kit?

I don't know of any, but I've never bought a complete kit from Moss.

Randall

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