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TR2/3/3A Is there a way to take apart and clean/repair TR3A headlight dimmer switch?

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TuffTR250

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Is there a way to take apart and clean/repair the inside of a TR3A headlight dimmer switch? Mine was very rusty and would not move. I sand blasted the out side and put a bunch of PB Blaster down in the push button. If I work and work the push button, at times I get continuity between the center connector (the one that gets power from the headlight switch) and the connectors on each side at separate times. So it would appear that the switch may be good, but just mucky inside and not allowing good movement inside. I have no idea what the inside of one looks like. It would appear that I could drill out the two "rivets" that hold it together by drilling from the front of the switch. But not sure what I'd do once I got inside. Has anyone tried to take one apart and clean up the inside? Thanks!
Regards,
Bob
 
I've had an early one apart, but it was too far gone to put back together. Later ones might be different, but as I recall there was a Bakelite drum with copper contacts mounted on it, and a ratchet mechanism that would turn the drum. Each terminal then has a wiper that rides on the drum.

Doesn't sound like you have much to lose by taking yours apart. Worst case, it still won't work :smile:

PS, that and the way the headlight switch is constructed, help convince me that headlight relays were a good idea.
 
Just did this on my TR4a. Remove the Knob by using pocking anything that fits into the hole on the side of the knob. Remove the retaining ring and the Dimmer should pull out the back. Disconnect the battery and remove
dimmer wires. There will be 3 prongs that hold the Cermaic back on. Pry them open and pull cermic back away from metal housing....use caution as some parts may fall out.
You will see the nichrome wire imbeded into the ceramic along with the center wiper....which is heavely oxidized. On the other side you will see the wiper the glides on the nichrome wire...look closely and you will see a pointy contact opposite the wiper. Make sure the Nichrome wire is not borken....its tought stuff and should be OK. Very gently sand the Wire Tip and point till bright and shiny. Do the same for the center ring of the ceramic. Before putting it togther use a light coating of grease, and put together.
Note: Make sure the stop is in the correct possition.
Test with an ohm meter to insure you get a small resistance change. Your good to go.
 
I think you are talking about the dash light dimmer, rather than the headlight dimmer. The headlight dimmer is a simple SPDT switch, as there are separate filaments in the headlight bulbs for "low" beam; no Nichrome involved.
 
If this is the "foot-switch" then Lucas are remanufacturing these. Their horns come from France. Maybe these do too.

I bought a Chinese one from Moss and had to dismantle it and fix it. Then new Lucas ones started to show up on Ebay.

Al.
 
I took mine apart and lubricated it and worked it and worked it, but still couldn't get it to "flip" correctly. I think the mechanisms are just worn out. So I bought an aftermarket dimmer switch for some GM car from CarQuest for $10 and made a new mounting bracket for it so I could get it up higher out of the way of the clutch. I much prefer this to the old original round TR3 switch. But then I'm not going for originality.
Regards,
Bob
 
alanjohnturner said:
If this is the "foot-switch" then Lucas are remanufacturing these. Their horns come from France. Maybe these do too.

I bought a Chinese one from Moss and had to dismantle it and fix it. Then new Lucas ones started to show up on Ebay.
Click to expand...
There were at least three different switches used, though, maybe more. They mount differently (so the bracket is different) and I think I remember that the captive nuts in the body moved around to match the bracket. My point being, if you buy a repro switch, be sure you're getting the one that fits your car. I believe all three are available from TRF.
 
At least two different Lucas branded foot-dippers offered at present on ebay.co.uk.

I got a TR4A one and it beats the Moss one hands down.

Al.
 
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