Wanted - egg shaped overdrive switch TR3A

[PXC]

I tried this in “For Sale and Wanted” but no luck so I’ll try it in this forum. 
Switch must be working, for a 1959 car. 
Thanks

Paul

 

[RogerH]

David Manners have one on Ebay for £100

Moss/Rimmer have them for £80

 

Roger

Edited November 4 by RogerH

[Lebro]

I think I have one, but it is not painted black, just natural alloy.

Let me know if intetested,& I will dig it out

[PXC]

Hi Bob

Yes that would be fine. I can paint it myself.

Regards

Paul

 

[Lebro]

Actualy found two of them. The black one is as good as new, I would want £60 for that, the unpainted one (with non standard fixing bolt) £10

Of course if you wanted to employ my "Logic" overdrive circuit I could modify one or the other prior to shipping ?

    

Operation is flick switch lever up for O/D in, down for O/D out, if in O/D & change gear it drops out.

Bob

[GreatOldOne]

That looks as if it could be ripe for a 3D printed version if they’re hard to come by… 🤔

it is after all a n over large shell for a three position switch (or I guess SPST if it’s original o/d in or out?)

[Lebro]

Original switch is actualy SPDT, but only one side is used.                                                                                            

Bob

[BlueTR3A-5EKT]

The original switch unit   Also used as a switch on older motorbikes.

 

 

Edited November 7 by BlueTR3A-5EKT

[Ian Vincent]

18 hours ago, Lebro said:

Actualy found two of them. The black one is as good as new, I would want £60 for that, the unpainted one (with non standard fixing bolt) £10

Of course if you wanted to employ my "Logic" overdrive circuit I could modify one or the other prior to shipping ?

    

Operation is flick switch lever up for O/D in, down for O/D out, if in O/D & change gear it drops out.

Bob

And I have mine mounted so that up is ‘off’ and down is ‘on’.

Rgds Ian

[james christie]

16 minutes ago, Ian Vincent said:

And I have mine mounted so that up is ‘off’ and down is ‘on’.

Seems more logical to this brain!

james

[BlueTR3A-5EKT]

This is the switch I’ve done for my brother’s cars which have Roger’s overdrive logic boxes fitted.    The switch is spring loaded passing contact.

 

[PXC]

On 11/6/2025 at 5:02 PM, Lebro said:

Actualy found two of them. The black one is as good as new, I would want £60 for that, the unpainted one (with non standard fixing bolt) £10

Of course if you wanted to employ my "Logic" overdrive circuit I could modify one or the other prior to shipping ?

    

Operation is flick switch lever up for O/D in, down for O/D out, if in O/D & change gear it drops out.

Bob

Hi Bob

That seems a good improvement. I am happy with the unpainted one, with the “logic” replacement switch. 
when you say the “overdrive relay” is the addition of the resistor the only other change (apart from the amended switch)?

As per my earlier post (overdrive dropping in and out) my J type overdrive has currently been wired without the relay in the circuit at all, just operated by the dash switch. But I will re-incorporate the relay when I wire in the new switch. 

Photo of the  relay - assume suitable for the logic amendment? It does work.

Regards

Paul

[harlequin]

6 hours ago, Ian Vincent said:

And I have mine mounted so that up is ‘off’ and down is ‘on’.

Rgds Ian

I believe up for off, down for on is the UK norm for electrical switches.

George 

 

Edited November 7 by harlequin

[Lebro]

5 hours ago, PXC said:

Hi Bob

That seems a good improvement. I am happy with the unpainted one, with the “logic” replacement switch. 
when you say the “overdrive relay” is the addition of the resistor the only other change (apart from the amended switch)?

As per my earlier post (overdrive dropping in and out) my J type overdrive has currently been wired without the relay in the circuit at all, just operated by the dash switch. But I will re-incorporate the relay when I wire in the new switch. 

Photo of the  relay - assume suitable for the logic amendment? It does work.

Regards

Paul

Ok, will modify the unpainted one & post off.  To achieve the "logic" function you need the resistor wired across the relay, & three  wires from the switch as per my diagram. Which way up you have it is up to you !  I can't see the pin descriptions of your relay, but as long as you can identify th two winding pins, & the two "normaly open" pins then it should work fine.
PM me your address & contact details.

Bob

[Lebro]

If you wanted to send your relay to me, I could check it out, & pre-wire it ?

Bob

[Ben Davies]

That’s a fiendishly simple way of setting up the logic facility, Bob!  Very clever. 

[Lebro]

I did publish it in TRaction a while ago, a few people have run with it.

Bob