TR6 Handbrake warning lamp switch build

[Gliderman8]

I just completed my brake lamp handbrake switch. Before I get into the "how to" let me say I am still looking for that "sweet spot" and I'm hopeful to find it with some adjusting of the mercury switch angle. If I can't find it, I may have to go to a mechanical or a proximity switch to solve the issue.

OK, I thought this was going to be an easy install; as it turned out, it was more involved. When I first hooked everything up, I noticed that my oil pressure lamp went OUT (without engine running) when the brake lamp was energized by lifting the handbrake. This had me stumped until I looked at the schematic and saw that the positive feed for the oil lamp went through the filament of the brake lamp. In order to correct that issue I had to move the positive wire to the oil pressure lamp as per the '76 schematic. Once I did that everything worked as it should.
Here's what I did:

Started with a mercury switch and a wire connector

I used the plastic body from the wire crimp and inserted the glass bulb into it.

Then filled the plastic body with epoxy.

Attach wire leads and heat shrink

ran a wire to the ground of the brake lamp

I mounted the switch temporarily with foam tape so I can reposition it to find the correct angle to keep it from flickering on during acceleration. (Note: you do not see the switch, I pulled back the leather handbrake boot to take the pic)

Lamp illuminated when handbrake is raised

 

[TuffTR250]

Elliot, I'm curious. Where did you run the wires from the switch up to behind the dash? Thanks!
Bob

 

[Gliderman8]

Elliot, I'm curious. Where did you run the wires from the switch up to behind the dash? Thanks!
Bob

The two wires from the handbrake switch run down under the carpet next to the passenger seat that is closest to the transmission tunnel. From there it runs under the carpet where the transmission tunnel meets the floor and then straight up behind the center dash support. All connections were made just behind the passenger radio speaker.

 

[DrEntropy]

Well engineered and executed, Elliot!

 

[Gliderman8]

Well engineered and executed, Elliot!

Hold that thought doc.... I'm still trying to find that "sweet spot". Brake light will momentarily flicker on acceleration. I may have to switch to a limit switch or proximity switch.

 

[DrEntropy]

Hold that thought doc.... I'm still trying to find that "sweet spot". Brake light will momentarily flicker on acceleration. I may have to switch to a limit switch or proximity switch.

Is there any way to set a N.C. micro-switch under the lever or behind it under the boot?

Been so long since I've been "intimate" with the TR's I don't recall the physical setup at the pivot point.

 

[Gliderman8]

Is there any way to set a N.C. micro-switch under the lever or behind it under the boot?

Been so long since I've been "intimate" with the TR's I don't recall the physical setup at the pivot point.

Don't know the answer to that until I pull the boot off the handbrake. What I'm hoping for is to find a place to mount the small magnet then attach a small proximity switch that I have under the boot. Stand by..... will update after pulling off the boot.

 

[poolboy]

What kind of switch was used on the 76's ?

 

[Gliderman8]

What kind of switch was used on the 76's ?

I believe it was a spring loaded switch that went to ground when the spring moved off of the handbrake.
Maybe someone with a ‘76 can tell us more.

 

[ed_h]

Is there any way to set a N.C. micro-switch under the lever or behind it under the boot?

Been so long since I've been "intimate" with the TR's I don't recall the physical setup at the pivot point.

Here's one way:

 

[Gliderman8]

OK, I removed the mercury switch and went to a micro switch like Ed did. Since I did not want to disassemble my handbrake I decided to add a "stop" to contact the micro switch button. I was able to run a 6/32 tap into the base of handbrake. The flat on the nut was just enough area for the switch actuator to make contact with.

Lever in the down position

Lever raised

 

[ed_h]

Looks like that will do the job, Elliot.

Ed

 

[Gliderman8]

Looks like that will do the job, Elliot.

Ed

Thank you Ed. I looked at what you did (it looks GREAT!) and just couldn't bring myself to disassemble the handbrake. I also tried a proximity switch but finding a place to mount it and the magnet did not work. In the end, the added flat on the nut was all it took for the switch actuator to work.

 

[DrEntropy]

Ed's setup is great. Well done, Elliot, too. Yankee ingenuity at its best!

I love micro-switches. I've used 'em to control the lighting in cabinets in kitchen and living room. Positive off and on, reliable for a lifetime.

 

[Gliderman8]

Ed's setup is great. Well done, Elliot, too. Yankee ingenuity at its best!
...........

In my case it was more like "Necessity is the mother of invention"