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Brake light switch
JeffJeffers - 2/8/12 at 10:26 PM

Now I have clocked up a few miles I'm having to carry out a few product enhancements, as Vauxhall would call it.

One is my brake lights only come on when I brake hard. I have done a search and it seems this can be a problem when using a hydraulic brake light switch.
I have read a few post with people saying they have used a micro switch on the pedal but can't find any pictures of how they have set it up.
Has anyone got a picture of how this might work with floor mounted pedals?


maccmike - 2/8/12 at 10:29 PM

do hydraulic switches not come in varying sensitivities?
Mines like that and requires little pressure to activate


Staple balls - 2/8/12 at 10:56 PM

Sometimes a little air bubble gets trapped in the switch making it not work right, easy enough to remove it and get the air out.


RK - 3/8/12 at 01:34 AM

I don't think you want microswitches quitting on you at inopportune moments. The hydraulic switches are reliable, hence their widespread use.


loggyboy - 3/8/12 at 06:26 AM

From what I've read its the hydraulic switches that fail more often. most modern cars use a mechanical switch. they are not usually micro switches. they just need to be secured to the pedal box, but depends on your layout.


britishtrident - 3/8/12 at 06:33 AM

Mechanically operated switches have been in and out of fashion with Tintop manufacturers over the years. in the 1970s and 1980s a simple NC (push to break contact) switch was fitted in place of the pedal stop, so as soon as the pedal was applied contact was made.

For example

Do an eBay search on "
lucas SMB419 "

or " Lucas SMB421 "/

The other alternatives are motorcycle or car brake light switches from the classic era these are usually pull type switches connected to the pedal via tension spring. You will find various types here.

http://www.completeautomobilist.com/categories/complete-automobilist-auto-electrical-switch


Keep in mind the current through the brake light switch is fairly high at 3 to 4 amps so you need a fairly heavy duty switch.

[Edited on 3/8/12 by britishtrident]

[Edited on 3/8/12 by britishtrident]


britishtrident - 3/8/12 at 06:52 AM

OEM 1960s Lucas hydraulic brake light switches were very reliable failure was almost unknown the ones on the market now seem to be crap.

The 1970s era Lucas mechanical switches were a little bit less reliable, mainly because they also functioned as the pedal stop and the two main parts of the nylon plastic body tended to come apart.
Pedal stop switches are often fitted to modern cars to operate cruise control systems.

[Edited on 3/8/12 by britishtrident]


loggyboy - 3/8/12 at 07:10 AM

Here's a typical GM setup.

Would be pretty easy to replicate that on most kit pedals. is your a floor or top mounted box?


gingerprince - 3/8/12 at 08:34 AM

I had the same issue, and did this: -

Brake Switch
Brake Switch

Brake Switch
Brake Switch


Microswitch is "normally on", so when brake pedal is not pressed the button is pressed to the "off" position. As soon as I dab the brake the switch opens to "on" and the brake lights come on.

I've left the pressure switch in situ, and the microswitch is wired in parallel, so if I am emergency braking and the microswitch has broken for whatever reason the brake lights should still illuminate.


loggyboy - 3/8/12 at 08:37 AM

A few discussions on the same subject:

http://locostbuilders.co.uk/viewthread.php?tid=170948

http://www.locostbuilders.co.uk/viewthread.php?tid=169898


maccmike - 3/8/12 at 09:05 AM

quote:
Originally posted by gingerprince
I had the same issue, and did this: -

Brake Switch
Brake Switch

Brake Switch
Brake Switch


Microswitch is "normally on", so when brake pedal is not pressed the button is pressed to the "off" position. As soon as I dab the brake the switch opens to "on" and the brake lights come on.

I've left the pressure switch in situ, and the microswitch is wired in parallel, so if I am emergency braking and the microswitch has broken for whatever reason the brake lights should still illuminate.



very good that


JeffJeffers - 3/8/12 at 09:09 AM

quote:
Originally posted by gingerprince
I had the same issue, and did this: -

Brake Switch
Brake Switch

Brake Switch
Brake Switch


Microswitch is "normally on", so when brake pedal is not pressed the button is pressed to the "off" position. As soon as I dab the brake the switch opens to "on" and the brake lights come on.

I've left the pressure switch in situ, and the microswitch is wired in parallel, so if I am emergency braking and the microswitch has broken for whatever reason the brake lights should still illuminate.


Now thats what I was looking for.

Thanks


snowy2 - 4/8/12 at 06:57 AM

i prefer hydraulic switches as getting into a "7" pedalbox area can be a real pain in the bum if you have to replace a mechanical switch......my car is still using the same switch as when it was built 34 years ago, and its covered over 20000 miles in the last 4 years and not given any trouble.