Brake Light Switch

47 Brake Light Switch question

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Lowbikemike
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Brake Light Switch

#1

Post by Lowbikemike »

The plunger on my 47 EL OEM brake light switch was very hard to pull. Opened up the switch, found things pretty much gummed up, cleaned everything and reassembled and works much easier. It appears there is very little in the switch to keep it from shorting to ground when the brakes are applied. Should there be an insulator on the brass cup that rides on the plunger? Should there be something insulating the plunger bottom end (larger end)? Did some testing with ohmmeter after reassembly, works fine, but sometimes when wiggling the plunger I do get continuity between a terminal and ground. Parts book doesn't show any serviceable parts. What do you think?



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Re: Brake Light Switch

#2

Post by 47str8leg »

Truly have to see a picture of the inside of what your talking about to see if there is a fix ( such as lightly applied silicone to act as an insulator between these questionable areas).
Tim

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Re: Brake Light Switch

#3

Post by Lowbikemike »

For those inquiring minds, here's what you'll find inside the brake switch.

The first picture shows the complete assembly.

Second picture are the components. When the brake is applied the rod is pulled foward and the brass cup touches the contact points.
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Re: Brake Light Switch

#4

Post by Lowbikemike »

The next two photos show how the cup is insulated from the rod and switch case.

I'm going to try and find a new lipped washer. The cup itself has a rubber insert that keeps the parts from grounding also.

If I cannot find a suitable washer its going back together as is. I don't think the rod has much side to side movement in normal operation so I should be good to go.
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Re: Brake Light Switch

#5

Post by RooDog »

So the cuped washer needs to be completely isolated from everything else? Correct?

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Re: Brake Light Switch

#6

Post by Lowbikemike »

That is correct.

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Re: Brake Light Switch

#7

Post by RooDog »

Mike....
How about taking an AM switch apart and sapping out what ever internals you may need to make the OEM case functional once again? I have done this with the dash mounted ignition switches as needed....
....RooDog.....

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Re: Brake Light Switch

#8

Post by 1950Panhead »

How about taking an AM switch apart and sapping out what ever internals you may need to make the OEM case functional once again? I have done this with the dash mounted ignition switches as needed....
The reproduction internal parts differ ... Mike needs and insulated washer and sleeve ... (been here, done that)

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Re: Brake Light Switch

#9

Post by Lowbikemike »

RooDog wrote:
Wed Feb 05, 2020 1:51 pm
Mike....
How about taking an AM switch apart and sapping out what ever internals you may need to make the OEM case functional once again? I have done this with the dash mounted ignition switches as needed....
....RooDog.....
Good idea, thought of that and took apart one of my aftermarkets.

As usual the aftermarket is not exactly like the OEM and generally speaking not as well constructed. The biggest obstacle is the larger end of the stem measures .355 and the OEM is .310, so the cup, washers, etc, wont exchange. The aftermarket isolates the cup in simliar fashion so you wouldn't be gaining much anyway.
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Re: Brake Light Switch

#10

Post by Larry »

Makes sense, the original is American (5/16) and the aftermarket is metric (9mm).

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