[TR] Alternative gearboxes for Triumphs

[Randall]

> Is it advisable to override the switch and let the OD run in all gears?

 

I would certainly advise AGAINST overriding the lockout switch!  Much too
great a chance of forgetting and leaving the OD engaged in reverse (the OD
will be badly damaged if it engages while the car is moving backwards).

 

My guess is that Dave is thinking of an A-type overdrive, used on early TR6
& Stag.  In the TR3-6 application, it came with an additional lockout switch
that enabled operation in 2nd gear.  I'm not certain offhand, but I think
the Stag did not have the extra switch even with the A-type.

 

But I think Sujit is talking about a J-type, as used on later Stag & TR6.
The J-type works differently, among other things it does not carry a
reservoir of high pressure oil to allow for instant engagement.  It takes
several rotations of the driveshaft for it to engage, which of course will
be much slower in 2nd gear.  It would probably still work OK though, if you
always make the concession of waiting for it to shift fully before applying
power in 2nd OD.

 

But if you do decide to allow OD in 2nd, I would certainly add the extra
switch rather than just disabling the existing switch.  I believe (not
certain) that the ramp on the back of the 1-2 shift fork is still there, so
all that is needed is to drill and tap the top cover for the second switch.

 

There is an article on the Buckeye Triumphs site with details on how to add
the switch.

http://www.buckeyetriumphs.org/technical/Gearbox/ODSwitches/ODSwitches.htm

 

-- Randall

 

 

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