Lotus Elan

Vacuum switch

PostPost by: Emma-Knight » Tue Aug 22, 2006 12:18 pm

My Vac switch happened to be opened, so I opened it again and found a very simple device inside: its a hollow rectangular rubber block connecting or disconnecting the headlamp pods to the vac tank. It is moved back and for by the switch handle, pressed down by a leaf spring.
Leakage could come from rust on the metall surface where the rubber moves. The rubber could also cause leakage (was still perfect in my car),
even the angeled tube soldering could leak. Its all hand build and soldered
so can be repaired. The rubber could simply be cut from massiv rubber block. I hand grinded the metall sealing surface with 1000 grade paper on a block and had it regalvanized with zink. The cover can be opened by gently undoing the 4 top "rivetings". the undoing of the vacuum (lamps down) is via the housing slots so they need to breathe!

I could add a picture of what is inside.

Anna :wink:
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PostPost by: chrishewett » Tue Aug 22, 2006 9:48 pm

An old engineer pal of mine always says " If it was made by man it can be repaired by man".
We could always add woman!
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PostPost by: gjz30075 » Wed Aug 23, 2006 12:56 pm

Yes, I'd like to see what's inside. This is one area I haven't been in yet. I can't get my headlights to stay down for more than a day. I believe its the switch leaking.

Greg Z
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PostPost by: Emma-Knight » Wed Aug 23, 2006 3:11 pm

..here we are:

The main housing was rezinked, showing the lower angled tube sunk down a bit, but still tight and workin - a factory option...

the cover housing has a clip riveted inside, two rivets showing on the outside. This clip snaps into one of two half-moon cutouts in the push/pull device, fixing up or down position. (cutouts not to be seen it in the picture)
The rubber block will face with its caved surface towards the two tube openings in the main housing, covering one (engine suction) or both (vac pod line) openings. When released, the air is sucked back through the housing slots to the pods.
The black leaf spring is between rubber block and push/pull device, pressing the block on the main housing flat.
So a clean, smooth surface is required to be air-tight. If the rubber is resistent enough, it might help to blow some WD 40 like stuff through the housing slots as dirt or little amounts of oxide or sticky substances may be washed away. Maybe better than opening as a first try.

Mine still holds together when clipped back.

PS: I should have turned the push rod the other way round, the two little arms facing towards the main housing, holding the leaf spring and rubber

Vacswitch02.jpg and
this is a better view of the rubber block cave
Vacswitch1.jpg and
the full assembly
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