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MG Midget and Sprite Technical - Brakelight switch

The second replacement hydraulic brake light switch was driving me nuts. I had to stamp on the brake pedal before the lamps illuminated. Bleeding and adjusting the brakes made little difference so I bought a £1.89 classic mini electrical switch from ebay.
My midget (71) has a predrilled hole for a brake light switch on the and with a little drilling and filing the switch can be made to fit. Friend Rob had already fitted a relay and a diode so these were retained just in case. The switch fitted perfectly and works by contact being made only when the pressure is released i.e. when the pedal is depressed and surprise, surpise the two wires from the existing switch were a straight fit for the new switch.
It operates just like a modern now and I can relax again! Picture shows installation and I need to mop up the swarf I know.

Jeremy
Jeremy 3

Picture 1


Jeremy 3

Picture 2


Jeremy 3

I love it. Thanks Jeremy.
Nick

Jeremy,

I like this simple upgrade as the standard hydraulic switches have a bad reliability record.

Can you please clarify the references to a diode and relay? Did you directly replace the standard switch with the Classic Mni switch [part 13H3735?] and use the existing wiring without modifications? Or did you need to use a relay and diode?

Doug
Doug Plumb

The replacement hydraulic switches are no worse than the mechanical switches - they are all crap unless you spend the bucks to get one of the switches provided by the Ron Francis Wiring company http://www.ronfrancis.com/ (the part number is SW 32). A number of years ago, I started using a relay and arc suppression circuit of my own design in conjunction with a standard replacement switch (both hydraulic and mechanical) and have not had any problems since. For instructions on making up the relay/arc suppression circuit, see the article, Brake Light Relay in the Other Tech Articles section on my web site at: http://homepages.donobi.net/sufuelpumps/ Cheers - Dave
David DuBois

Doug -
"Friend Rob had already fitted a relay and a diode so these were retained just in case."
seems clear enough to me...
David Smith

David,

From the photos:

The green wires to the switch appear to be original – ie from the hydraulic switch

Assuming the black box is the relay, it doesn’t appear to be connected to the switch


Hence my question.

Doug
Doug Plumb

Ah, as my colour vision is defective I can't see that level of detail...
David Smith

Doug,

you're correct the black box is the relay and the wires are the original wires from the hydraulic switch. They are all still connected and I'll take a couple more photos to show how.
I did visit and read David (Dubois) very good website as it appears in the archives as does other good advice on how to preserve the replacement switches i.e. using a relay. The diode was added as the relay interfered with the ICE - well an MP3 player and small amplifier! This was also advice from the archive.
Bootom line is I don't have to worry about people behind me not realising I'm braking and it was a very simple conversion.

Jeremy
Jeremy 3

Jeremy,

I look forward to the additional photos for clarity.

Doug
Doug Plumb

I had a full on girly tantrum today, I found a great SOB tool and threw it against the garage wall.

Someone please tell me why the two mounting bolts nearest to the firewall are screws and nut 7/16th bolts like the other four. It took 2 hours to drill them out as they where mashed beyond recovery. I picked up a Landrover brakelight switch today, same thread and fitted perfectly. The only thing is that a landrover switch is push to brake not push to make, that was my first little tantrum, I them went for a Mini one, of course that means removing the pedal box the drill the hole out....ARRRGGGHH!!!!!! Anyway, I am doing what prop tells as all to do, and have a break, coffee, TV, F1 in the morning and then its angle grinder time!!
N Sayle

Doug,

sorry not had time for the camera yet - helping said friend Rob replace n/s sil on his MGB but will take a couple today.
N Sayle - you shouldn't need to remove the pedal box especially if there's already a small hole - it was possible to drill it out in situ; not easy but not as difficult as removing the pedal box. I also filed both sides of the swith to help it fit the enlarged hole and that helps stop it rotating when you're tightening it up.

Jeremy
Jeremy 3

Jeremy, yes I have since discovered the angle I could have enlarged the hole, however, It has given me the chance to strip down the starboard side of the engine bay and get it ready for priming and painting. I found all good metal under the layers of gunge so I'm really please. it will look nice with when it done. I have tapped out the mounting bolts to 8mm and will fit stainless allen drive cap heads, not going through that one again
N Sayle

those two at the top were screws from the factory because it was too small of a work space to fit a socket driver under the pedal assembly's stiffening flange.

You can fit hex head bolts now, of course, because you are not in as much of a hurry as the guys on the assembly line were, you've just gotta use a box end wrench to tighten all of the way.


Norm
":oD
Norm Kerr

N Sayle,

good excuse to have a thorough examination! I use plenty of copper ease as well for all bolts etc.

Doug,
picture attached which hopefuly shows how the wring links up. I was mistaken the original wires go the the relay with new wires (cut from the old loom - hence the confusion) from the relay to the new switch. Hopefully the picture will help show what I mean althoigh it's pretty crowded there!

Jeremy


Jeremy 3

Well my slightly intermittent brake light switch has turned into a proper saga. I have just ordered a new mechanical late type switch, will be here tomorrow. So, today, I will replace the master cylinders and pedal box water heater tap and fuse box now the paint is dry. It has given me chance to clean the whole area down to bare metal, A coat of etching primer, 3 red oxide, and 2 top coats. Due to the fluid spills over the years it was al a real mess. The pedal box found its way into the kitchen sink where I spend a couple of hours cleaning it down for re painting. When my hands started to hurt I decided it was clean enough for a coat of paint as I realised I was going a bit over the top for a lump of metal that only I will see. I then found the Mr Muscle oven cleaner under the sink. I though, why not. It is now gleaming shiny and clean. The whole area I have brought back to new is just over 1 square foot. But a whole weekends work, I wonder whats next!!!!!


N Sayle

Clean enough to eat your dinner!

Jeremy
Jeremy 3

all this because I had to change the brake light switch!!! I'm happy with it though, couple of fiddly things to do yet like connect the new switch and re tap the cover plate screw holes. these will be stainless cap heads as well. whacked on the new air filters as well, they make a massive difference!!




Nick Sayle

This thread was discussed between 13/04/2010 and 20/04/2010

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.