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Re: TR6 - GT6 trans swap

To: Martin Secrest <msecrest@erols.com>
Subject: Re: TR6 - GT6 trans swap
From: Bill Birney <bill.birney@bigpond.com>
Date: Mon, 11 Oct 1999 15:29:33 +1000
Cc: Craig Parman <cparman@siue.edu>, triumphs@autox.team.net
References: <38010C9E.BA0455E2@siue.edu>
>I think you have a transmission for sale.  The GT's frame rails are too
narrow to accept 
>pretty much anything other than a GT6 transmission.

Not quite true.

The 4 speed box will drop into the GT6 with no modification to the car
(other than cutting back the top of the tunnel sheet metal). But some to
the box

This will require a new gearbox mounting plate (a piece of 5mm plate which
bolts in place of the existing plate and extends about 25mm further back
and two pieces of square tube mounted at 45 degrees and slotted take the
gearbox mounts), and some blocks welded to the tail housing of the gearbox
to take the standard GT6 'cotton reel' gearbox mounts (requires a tig, but
can be done at most good machine shops). Also requiring modification is the
gear lever and the clutch mounting plate and actuating lever (the actuating
lever happens to coincide with the chassis rail without modification!).
This will fit under the standard gearbox cover (although the gearlever hole
will need to be extended backwards slightly and made larger).

Now for an overdrive box it is a little more complex. The A type box needs
lots of mods to the chassis due to the physical size of the OD (however it
can be done - we have one car in the club with this setup). The J type need
less modifications, but still 3 places need cutting (releif for the back of
the solenoid on one side, releif for the back rh corner of the od sump on
the other, and the cross member needs modifying to allow the angle drive to
fit.), and a new cross member needs to be added just in front of the old
one to take the gearbox mount. A new / modified gearbox cover needs to be
made to accommodate the extra bulk of the od at the back of the gearbox.

For either case you need a TR6 engine backplate, flywheel, clutch etc. I
suggest the flywheel should be put on a serious diet - when you compare the
GT6 and TR6 flywheels you will understand why!

I can provide some photo's of the 4 speed box and mountings (as modified),
as I still have the box I pulled out of the GT6 when I put the J type OD in
(both these boxes are from 2500S sedans so are basically the same as the
TR6 box, possibly with slight changes to speedo output position). I can
take some photo's of the OD fitment, however that will have to wait until I
have time to pull the car apart (ie interior) to get them!


Bill Birney
Melbourne, Australia

'67 Spitfire  MkII - Under resto
'70 GT6+ (RHD)

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