Subject: [TR] Replacing TR2 gearbox with TR6 gearbox

From: "ashleys" <[email-masked]>
Date: Thu, 21 Feb 2013 20:51:53 +1300

Hi!,What does one look for changing long door TR2 gearbox with the later 1970
TR6 overdrive gearbox.Ie clutch/driveshaft.Any thoughts would be welcomed.
Thanks,
Ashley

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From: "Randall" <[email-masked]>
Date: Thu, 21 Feb 2013 01:06:08 -0800

> TR6 overdrive gearbox.Ie clutch/driveshaft.

Keep your old clutch setup, it will work with the TR6 box.  You may need to
do something creative with the clutch slave cylinder mounting, as the TR6
box is thicker in that area.  On my TR3/A I just made up a shorter pushrod
to account for the difference (but it has the Girling slave instead of
Lockheed so your solution may be different).

I installed the TR2/3 brass bushings to carry the clutch operating shaft,
and added zerks so they could be greased.  Not necessary, but should reduce
wear in that area.

The driveshaft will bolt right up, the sliding spline has enough range to
cover the slight increase in overall length.  Be sure to replace the Nyloc
nuts.  I prefer to use all-metal lock nuts (aka Stover nuts) as I've found
that even new Nylocs will back off sometimes.  Note that the bolts are
specials but available from the usual suspects.

Slot the holes in the rear crossmember, to allow for the extra length (about
3/8" or one bolt width).  I also had to fold down the lip at the back so it
wouldn't rub on the mount.

You'll probably need longer studs and bolts on the back of the engine.  The
studs can't be too long though, or the output flange will hit the tunnel
when trying to R&R the gearbox with the engine still in the car.

Although not necessary, I swapped the TR6 shift linkage components into an
early top cover, so I could keep the dipstick.  If you do keep the TR6 top
cover, you'll probably want to install the TR2 shift lever, which may
require drilling out the holes on the sides.  The TR6 lever will work, but
is longer (and curved) and just looks odd to me.

Of course you'll need the OD wiring if you don't already have it, but that's
covered in the manual.  I added an in-line fuse in the hot wire to the
relay, so the fuse will open if the solenoid gets stuck in some manner and
the cutout contacts don't open.  Hopefully that will save the solenoid from
overheating and letting out the smoke.  Of course that means the OD will
drop out, potentially over-revving the engine, but I figure that will happen
anyway when the solenoid burns up and my engine doesn't seem to mind brief
excursions to 6k rpm.  I used an 8 amp "slow blow" fuse just because I've
got a bunch of them, but an ordinary 10 amp (or even 5 amp) fuse should do
fine.

The original relay lasted a long time; but replacements seemed to fail
quickly until I added a snubber diode from the load terminal to ground.  Not
being a stickler for originality (obviously), I just used an ordinary
Bosch/Tyco type automotive relay from the local parts store.

It's probably worth doing a pressure test on the OD, and replacing the
isolator switches before installing it in the car.  I put in an iffy switch
for 2nd gear and I'm regretting it now as it stopped working the other day.

-- Randall

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From: [email-masked]
Date: Thu, 21 Feb 2013 17:04:31 -0500 (EST)

Hi!,What  does one look for changing long door TR2 gearbox with the later 
1970
TR6  overdrive gearbox.Ie clutch/driveshaft.Any thoughts would be  welcomed.

Ashley:
Let me get this straight - You have a TR2 Long  Door and you want to use a 
TR6 transmission.  Why would you purposely  ruin the rarest of the rare?  
Sounds like someone just gave you a free  TR6 transmission with overdrive.
 
Lou Metelko
Auburn, Indiana

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From: Chris Simo <[email-masked]>
Date: Thu, 21 Feb 2013 17:36:15 -0500

I have a longdoor TR2 - The original transmission is not an overdrive and
was, well overdue for a rebuild. I put a TR4 transmission in the car for
now and  I'm looking for an old overdrive I can rebuild and I'll put that
in there next.

I've saved the original transmission for the future caretaker of this car.
 I've kept all the original bits and boxed them carefully for the future
owner. I recommend you do the same.

The TR4 transmission was still a bit of work to fit.  Slotted the
transmission mount and also loosened up the motor mounts and pulled the
engine as far forward as any slop would allow. It's just a bit longer than
the TR2 but fit and all covers bolt down nicely.  Clutch slave cylinder
bolted up just fine .  I seem to recall the TR4 transmission flange is
thicker than the TR2 so it may be a similar exercise to fit the tr6
transmission. No issues with driveshaft.  If unsure - I'd go ahead and
replace the universal joints while you have it out.

Since you have an early TR2 - you'll have the push pull overdrive switch
that fits into the dash  vs the toggle switch version.  I'd connect that to
an external relay and control the overdrive wiring that way.

I still want an overdrive,  I feel so bad when I take the TR2 on the
highway and the RPMs are over 4000 to get to 70mph.  It must have a low
gear in the diff.

Until then, we'll motor on and stay off the big roads as much as possible.

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From: [email-masked]
Date: Fri, 22 Feb 2013 01:50:04 +0000 (UTC)

Lou, 

Would you be happy if the TR2 gearbox was converted to o/d? One could remove the o/d from the TR6 'box and install it on the original TR2's. Just need a mainshaft. 

Ed

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From: "Randall" <[email-masked]>
Date: Thu, 21 Feb 2013 20:40:31 -0800

> Would you be happy if the TR2 gearbox was converted to o/d? 
> One could remove the o/d from the TR6 'box and install it on 
> the original TR2's. Just need a mainshaft. 

"Just" he says, like changing the mainshaft is as easy as changing a tire!
<G>

And some light modifications to the adapter plate IIRC.  The difference
wasn't much, but ISTR that unless you remove some metal, the TR6 plate won't
sit properly on the back of the 3-synchro gearbox.

-- Randall