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TR2/3/3A Brake light switch.

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DavidApp

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When I rebuilt my TR3A I decided to go with the micro switch setup for my brake lights as I had read about all the headaches people have with the hydraulic pressure switch.

I bought a switch from one of the local auto stores. That one failed after being a pain to get adjusted. I replaced it with a better micro switch I had from work. It snaps open or closed.
I have noticed that it works some times then other times it does not even though it is Snapping closed as I press the brakes. Possible it is not suitable for DC current.

Any suggestions on a good brake micro switch?

David
 
Most folks in Europe with this problem fit a BMW switch. - sorry don’t have the part number - plenty of other sources on internet

james
 
Thank you.

I have a BMW one on order from a local Non BMW supplier. Should be there in the morning. Will be glad to noyt have to check the brake lights every time I drive.

David
 
I use a metal mechanical switch sourced from TRF for a TR4. It's mounted to the brake mc/pedal box in the engine bay. It's been working in my TR3 for more than a decade.
 
David, did you remove the original switch due to failure or just in case? maybe you can refit it.

Graham
 
David,

Ditto JFS with the TR4 switch. I’ve used the same one for close to 10 years with no issues. Prior to that I used two TR3 switches and both failed probably due to the use of silicon brake fluid.

Tom TCF 3B
 
I too changed to switch activated by the brake pedal so that it is pretty much completely hidden. Works very well and making a small bracket was pretty easy. Was sure I had some pictures of installation and the part itself, but can't find them. Will post update if I find those pics. Cheers, Mike
 
Hello Graham

I did leave the original switch but fitted the micro switch just in case the original failed or did not work. It was easier to modify the wiring harness while I had it opened up for the alternator mods.

David

Graham H said:
David, did you remove the original switch due to failure or just in case? maybe you can refit it.

Graham
Click to expand...
 
Precisely what kind of microswitch did you use? Most of the ones sold for general electronic use cannot handle the current used by brake lights. They often can handle substantial AC current, but not DC.

I think I'd use a switch that is specifically designed for brake lights.
 
I used this switch from Amazon:

https://www.amazon.com/gp/product/B...rue&ref_=ox_sc_sfl_title_9&smid=ATVPDKIKX0DER

Pedal operated, not a Triumph but British:

Mwjls9K.jpg
 
A bit of a tangent on this subject: Both wires from my brake light switch are green, therefore I can't distinguish them. Does it matter how they're connect to the green and green/purple wires off the harness?
 
Cool. Thanks!
 
Here is a photo of the connector on the switch I am trying to use.

May have to go to a junk yard to get the pigtail.

David

Brake light switch s.jpg
 
Mike , I am in the final stages of restoring a 54 Long Door. The green and green/purple are not long enough to reach the hydraulic brake switch. I was going to just splice wires so they will reach. If the switch doesn't work, I will try one activated by the brake pedal. Does the switch you bought operate as a contact switch, when you step on the pedal?

Dick Vinal
 
Redoakboo said:
Mike , I am in the final stages of restoring a 54 Long Door. The green and green/purple are not long enough to reach the hydraulic brake switch. I was going to just splice wires so they will reach. If the switch doesn't work, I will try one activated by the brake pedal. Does the switch you bought operate as a contact switch, when you step on the pedal?

Dick Vinal
Click to expand...

Hi Dick

Switch I used closes as the pedal is moved away from the switch. Here is a picture I just took of my set up showing my homemade bracket and the switch. Has worked very well for a few years.

Cheers, Mike

Switch_and_Bracket (Medium).jpg
 
Perhaps the ideal switch would be a used TR4 switch - mine has been in service for 56 years. They look like this:

triumph-tr4-tr4a-brake-light-switch_360_e8aff60b39c261f25f557fffda44be1f.jpg


It mounted on the pedal box about where the TR3 stop bolts were once used. NOS ones come up on eBay from time to time for little money - I even bought a spare which should guarantee I never need it.

Oddly, the switch used on the TR4 was made by Delco (in England) rather than Lucas.
 
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