27 replies to this topic

[yorkshirechris]

I have a 1980 Mini GT...

The brake lights only come on when I really press down the pedal, the pedal is quite stiff as it is but I'd say I need to push it down 50% of the way in order for the lights to come on... which is quite worrying at times.

It's an electric switch so I've been told, what's the best way to adjust it so it comes on when I actually start braking?

If it can't be adjusted, do I need a new switch? How easy is this to do?

Cheers!

Chris

[Retro_10s]

Hi chris.

The switch is located behind the brake pedal and screws onto a tab on the pedal box with one big bolt on the back, you should be able to see it if you look under the pedal arm, it's usualy white and has two spade connectors going to it.

I can't remember if the switch is 'ON' or 'OFF' when it's compressed,... but if you look at it you can see how it works... you might be able to shim it out slightly but this will only work one way.

Easy to replace (could be fiddly if you have sausage fingers lol) as it just screws out once the spades are disconnected.

[yorkshirechris]

So it's accessible from inside the car? It's not somewhere on the car where I've worked or looked at before to be honest

Is the switch the only thing it can be, really?

[Southy]

Its easily ajustable as its on a slide located in the side of the pedal box roughly with abouts 1 1/2 inch travel held in plce by a single nut. Its a push to break switch memory serves me right so in your case it will need to be a ajusted so that its further away from the pedal arm itself so it disengages sooner.

[Retro_10s]

The switch is plastic so it's unlikely that bit on the pedal that engages it is worn and there's nothing else in the circuit to go wrong.

Might just need a darn good clean though... or try adjusting it up as Southy suggests

[yorkshirechris]

Mmm.. I don't quite get this bit...

it will need to be a ajusted so that its further away from the pedal arm itself so it disengages sooner

stupid question, is the pedal arm the actual thing that the pedal is mounted on? I guess it will make much more sense when I see it for myself.

I'll have a little play with it when I get chance anyway.

Cheers people

Edited by yorkshirechris, 01 March 2009 - 02:00 PM.

[Southy]

You can see on my pedal box here the slides at the bottom of the pedal box, your switch will be sat here with the pressure switch pointing backwards and the 2 spade connectors facing towards the drivers seat

[yorkshirechris]

Ahh I see... where exactly is the switch located in that picture then?

[Southy]

Mmm.. I don't quite get this bit...

it will need to be a ajusted so that its further away from the pedal arm itself so it disengages sooner

stupid question, is the pedal arm the actual thing that the pedal is mounted on? I guess it will make much more sense when I see it for myself.

I'll have a little play with it when I get chance anyway.

Cheers people

Basically the brake light switch is a PTB (Push To Break), whilst the pedal isnt pressed the arm at the top of the pedal is pressed agaisnt the switch breaking the circuit. As soon as you press your brake pedal, pressure on the switch is relased allowing it too create a circuit. Your pedal is having to travel further to allow this to happen so the switch needs to be moved to the left as your looking at the slide side on to allow it too make the circuit sooner once the pedal is pressed.

[yorkshirechris]

What is this 'slide' you speak of? I take it it is accessible from inside the car?

[Southy]

Its the holes circlied in red in the picture below.
Not sure which one of these it uses exactly, its just one nut along with a tabbed washer holding the switch in place, its easily accessible from inside the car yes, had to re-ajust mine when I built the car due to the same problem as yourself.

Edited by Southy, 01 March 2009 - 02:18 PM.

[yorkshirechris]

Now I'm a bit confused the way I understood it was that the switch was mounted "above" the pedal so when I press the pedal, the pressure came off the switch...

But if it's mounted under the pedal, surely when I press the pedal, it will put pressure on the switch?

[Southy]

The picture is a bit misleading and I understand why your confused, perhaps the pic wasnt the best example to use in this situation. Currently in the pic there is no pressure on the pedals and the linkages on them arent connected so the return springs on the pedals have pushed them all the way up, in reality when connected to the bottom of the brake and clutch master's they will sit a lot further down.

Have a look at your pedals and you will soon see how I mean.

[yorkshirechris]

Ah I see, so the pedals actually sit lower down than the slides you have circled in the pic.

Thanks for your help

[dklawson]

Early cars used a hydraulically actuated switch mounted on the right side of the front sub-frame. They were not adjustable. The pedal actuated switches came later, I'm not sure what year they were introduced.

You are correct, the standard switch should be referred to as a "normally closed" switch. When the pedal is all the way "up" it holds the switch contacts "open". Pushing the pedal downward moves the pedal away from the switch plunger allowing it to move forward in the switch, closing its contacts. A simple implementation of this can be seen in this MGB picture link:
http://www.britishv8...nMasters-GE.jpg
This car has a lot less clutter around the pedal assembly so it's easy to see how the switch is "generally" mounted and how pedal actuation will allow the switch to change.

This link shows a very simplified schematic of the mechanics (for a generic car). The switch in this link is shown just above the pedal return spring.
http://www.howstuffi...brake_pedal.jpg

Almost all British cars I'm familiar with eventually used a brake switch that looks like the one in this link:
http://www.minimania...ges/13h3735.jpg

It's quite likely that all you need to do is locate the switch and adjust the stop nuts (or reposition the switch bracket) to reposition the switch "further up", away from the pedal so less pedal travel is required to close the contacts.