Brake Pedal - Switch

[Colin]

Hello Team!

Here I go again;

I've been playing today. I discovered, following one electrical red herring that seemed to have summat to do with the hazard switch I'd fitted recently, that my brake lights weren't operating. The red herring did kind of relate to the brake light circuit initially, but on measuring volts in and zero volts out of the brake pedal switch, decided this was the culprit and have ordered a new one through the club.

The original (or at least the one I took out) was Delco. All plastic. And it sits in FRONT of the brake pedal. It has no moving parts. I expected to see a plunger that would meet with the welded square pad on the brake pedal and cut the current to the brake lights in an arse-about-face type opposite of the conventional switch ( push for 'on' etc..).

So  . . . how did it work?? No moving parts; long thread, wider body (don't know why) - looks as if it may have been filled with fluid - but I can't actually imagine that. Club accessory book makes it look as if the new, lauded all-metal switch has some type of plunger.

What's the real design of this switch, folks??

Best,

Colin.

[Colin]

Think by looking online I've answered my own question - they all seem to be plunger-driven.

Mine must have its plunger jammed in . . . P'raps I can fiddle with it . . .  😉

Best,

C.

[Badwolf]

I bought a plastic one a couple of years ago and shortly after fitting it, it exploded all over the driver's footwell. Finally found all the pieces but many advocate a version with a metal body. I did have a link to one on fleabay a while ago. I'll try to find it.

[Colin]

Thanks Badwolf!

I have ordered one of the Club's - all metal, apparantly.

Because my original has nothing in the way of moving parts, I couldn't figure how it operated. I think thd plunger is either completely stuck in, or part has snapped off.

When the club replacement comes, I'll disect the old one!

[Badwolf]

Colin - I appreciate that you have ordered a new one, but you might find this thread of interest...

https://forum.tssc.org.uk/topic/5058-brake-light-switch-poor-quality-parts/#comment-60145

Also this...

https://forum.tssc.org.uk/topic/4967-led-fuse-failure-light/#comment-58955

I think that this was the one I bought eventually..

https://www.ebay.co.uk/p/25017000539?iid=302943046841

[Colin]

Hi Badwolf,

I honestly did a search before I launched my new thread! No resukt.

Yep - all the wording was very confusing in some of those threads but the other Colin came to the same conclusion I did.

My confusion was there has been no semblance of moving part in the old one (in that photo I posted).

But it couldn't be anything else other than plunger extending and making the circuit whilst the pedal is depressed, once thought about (and others looked at online!!).

Thanks a lot! 😉

C.

[Badwolf]

If your plunger isn't stuck inside the body of the switch then it has probably departed and is lying around somewhere. It happens to us all. As for the search routine, the trick is knowing what to search on or a couple of words. I think in this case it was 'brake' (and) 'switch'.

 

 

[Josef]

The arse about face switch is more usually called a push-to-break (break the circuit)  vs the push-to-make which you’re describing as a conventional switch. Love the new term though

[Pete Lewis]

this switch was commonly used by many it  makes contact as soon as the pedal moves away from the switch 

there is a problem with all these  it really needs a steel nut to hold the swittch and also act as a pedal bacl stop

relying on the switch and its plunger as the foot off back stop untimately wrecks the switch  it often pops the switch apart or the button fails 

the solution by many makers was to use a deep nut so the pedal strikes the nut not the switch

Pete

[NonMember]

1 hour ago, Josef said:

The arse about face switch is more usually called a push-to-break

Also referred to as N/C (for "normally closed"), where the more usual push-button is N/O ("normally open")

[Peter Truman]

47 minutes ago, Pete Lewis said:

the solution by many makers was to use a deep nut so the pedal strikes the nut not the switch

Always wondered why the nut was so big thanks for the info PL, have found the aftermarket white switch's are not long lasting but our local Jaycar, your old Maplin type electronics chain has an alternative which is crimped steel case and fit for purpose also under $10

[Colin]

PL - indeed it was secured by a large steel nut - I thought even by my own standards somewhat over engineered but now I can see why!

Seems Triumph liked this kind of plunger switch - after all, the courtesy lamp, door switches are just the same on a smaller scale, aren't they!

Best,

C.

[NonMember]

20 minutes ago, Colin said:

the courtesy lamp, door switches are just the same on a smaller scale, aren't they!

No, they're even less well engineered. At least the brake light switch is actually a switch. The door ones use the bodywork as one of the terminals.

[Pete Lewis]

the club shop version(and sold by others ( is a prpoper metal bodied switch not a cheap nasty plastic pop together orrible thing 

we used this plastic abomination   on trucks back in the 70s it was a nightmare and as i said used by far too many makers its failings are not new  

Pete

[Clive]

45 minutes ago, Pete Lewis said:

the club shop version(and sold by others ( is a prpoper metal bodied switch not a cheap nasty plastic pop together orrible thing 

To be fair the original plastic ones are pretty good. The new "lucas" tat in plastic is about as long lived as a packet of hob nobs in our house. 

My worry about many of the metal bodied ones is the source. If lucas (likely) it is always a concern. However, I would hope even they could make one that lasts. After all, the switch is incredibly simple.

I found an OEM switch from a VAG car that was perfect substitute. Cost about a tenner, but most recent vehicles seem to use bespoke switches that are unsuitable for our cars.

[Colin]

I decided to patronise our Club shop! 🙂 

[Colin]

I will say now:- I understand this switch is a plunger operated switch.

Now, as is my way, I've butchered the old Delco (poss original?) switch (pics).

I cannot, for the life of me, having pushed what should in theory be either end of the plunger, move any part of it! 

And therefore, not understand how this switch until recently, actually worked!! 

Additionally, I cannot report to have found any of what might be considered to be the 'operating' end of said (in my case alleged) plunger in the footwell, broken off, without me realising what it had been part of! 

Pics follow.

Thoughts/comments appreciated!! 

[NonMember]

The plunger is inside the threaded part but has become welded to the outer tube. Your photos look like it failed in the "on" position, though, so I'd expect a bit to protrude at the end. Note that if you sit your foot on the brake pedal for a few minutes with these switches, the current through the brake lights flows through the not-very-good contact between those terminal posts and the copper disc behind the spring, and the resistance in there creates enough heat to melt the plastic, thus welding the plunger in place.

[Colin]

Hey Non Member!

Thanks. Yes, it shows that it's been a bit overheated.

Not a foot-on-brake kinda guy, but I'm sure I've had to use it more recently. 50 years (potentially) in, I give it full permission to fail! 

Cheers,

C.