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[MikeT]

Has any body got a picture of the correct indicator switch for a 1959 registered SWB.  They are coming up on ebay regular but 2 different tyoes.

[rosinante]

Mine has a vacuum self cancelling switch , google will show them , not cheap at about 140 quids, it doesn't self cancel any more , white handle and an orange dash light , all mounted on accessory panel , car is ex mil 1959,
Chrus

[MikeT]

Like this one?

[MikeT]

Oops no picture

[Peter Holden]

That is indeed the correct switch for factory fitted ones  Page 457 in the parts book.  Part no 271108 or Lucas part no LU031296

Magnatex switches wera also an option

Peter

[diffwhine]

Purely out of interest, how did those vacuum self cancelling switches actually work?

[Peter Holden]

I believe there is a leather diaphragm inside, they go wrong when it dries out and splits.

Peter

[diffwhine]

Thanks Peter. So am I right in assuming that the way it works is that they take a vacuum feed from the engine and that vacuum controls the release of the switch in either direction for a pre-set amount of time? I guess that can't be more than about 15 seconds. Ingenious even though possibly somewhat overengineered!

[Peter Holden]

No, no connection to the engine.  Move the switch and itpulls the diaphragm out of shape creating a vacuum inside and it pulls the switch slowly back to centre.  a very simple device really

Peter

[AlexB]

There is a supposed "fix" whereby you take them apart, grease the leather and place a thin bit of card behind it - to compensate for wear - which is meant to allow a vaccum again

I have tried this on 2 but without success

[diffwhine]

No, no connection to the engine.  Move the switch and itpulls the diaphragm out of shape creating a vacuum inside and it pulls the switch slowly back to centre.  a very simple device really

Peter

Every day should be a learning day! Thank you!

[Marky Harvey]

Thanks Peter. So am I right in assuming that the way it works is that they take a vacuum feed from the engine and that vacuum controls the release of the switch in either direction for a pre-set amount of time? I guess that can't be more than about 15 seconds. Ingenious even though possibly somewhat overengineered!

As you rotate the lever it depresses the piston against a spring. The force of the spring pushes the piston back, but the return speed is limited by restricting the ingress of air into the chamber, through a piece of wadding. You can have my old one to look at if you like.

[JonB]

I think there’s a repair guide on the main sites technical docs, which I supplied a while back. I’ve brought a couple back to life, they’re very simple inside 👍

[Biglandy130]

As you rotate the lever it depresses the piston against a spring. The force of the spring pushes the piston back, but the return speed is limited by restricting the ingress of air into the chamber, through a piece of wadding. You can have my old one to look at if you like.

Next pub meet you come to remind me to bring mine I have one not attached to the vehicle yet