Overdrive column switch - parts interchange?

[rhalkyard]

The overdrive column switch on my Mk1 is very touchy – it will only engage if moved in just the right way, and often disengages going over bumps and the like.

I'm based in the US, and I've noticed that the usual suppliers (Moss Motors et al.) have a column switch for the TR4 that looks very similar to the Mk1 2000's switch, though it's hard to tell from the small photo. I've also seen one for the Volvo P1800 that again looks close, but it's hard to tell. Could anyone confirm whether either of those cars do use the same switch, or if they're known to be common to any other cars?

Alternatively, has anybody had success in rebuilding an overdrive switch? I imagine that my problem is just dirty or displaced contacts, but I'm hesitant to rip into something like that without prior knowledge.

[TedTaylor]

I am awaiting delivery of the TR4A type (couple of days) from Chic Doig and others who sell on ebay.

It looks as though it is OK apart from needing to swap the round button on the end and possible direction the switch operates but that should not be a problem.

I'll report back next week when it arrives.

MUT

[rhalkyard]

That would be a huge help. Thank you!

[TedTaylor]

Received the switch today but found that the overdrive switch for a right hand drive TR4A is NOT really suitable - the on-off positions are reversed when switching forward and back and the kink in the arm makes it not possible to swap over.

I am checking with the supplier whether the LHD ones fitting on the other side of the column will give the suitable action. Mind you if all else fails I suppose you could use the RHD ones and accept the different switching action.
I'll advise if I get any more info.

The reason I am trying to get a replacement is that the original one from my August 1964 car had become very rusted in storage and although they could be painted silver it won't look right.

MUT

[johnnydog]

I probably have a secondhand genuine / original steering column Mk1 overdrive stalk if you are struggling to find one. There are two different types; one has a slightly longer chrome stalk from memory. If you are interested, then let me know and the length of your old one and I will check the ones I have.
John

[TedTaylor]

Thanks Jon I'll check.

MUT

[TedTaylor]

I am checking with the supplier whether the LHD ones fitting on the other side of the column will give the suitable action. Mind you if all else fails I suppose you could use the RHD ones and accept the different switching action.
I'll advise if I get any more info.

MUT

Checked up on this. Because of the way the arm is bent it would appear that you would have to use a RHD one and accept that the switch works the other way round - on is off and off is on

In other words when the Mk1 switch is in the mid position it is off but with TR4 it is on.
When you move the switch up, with the Mk1 it is on but the TR4 is off.

MUT

[tony]

Ted,
Do you have Irish ancestry.
Tony.

[rlubikey]

Add a relay to reverse the sense of the switch!

Cheers, Richard

[Mike Stevens]

There should be a relay in the circuit anyway. I can't remember, but if it is a Change Over type (C/O) then the other contact (Normally Closed (NC)) could be used.

However, that would mean that the relay is energised when the overdrive is Out, and energised when it's In. Shouldn't really matter though.

Ted, I'd have thought that someone with your experience should be able to sort it!

Cheers,
Mike.