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MG MGB Technical - LED Brake Lights

Hi,I'm having the usual problems with BL switches burning out.
Before I go down the relay option would another solution be to replace the bulbs with LED's since the current draw would be considerably less?
And can anyone please tell me the original Lucas number for the hydraulic brake switch and what the thread/fitting data is?
(68 GT)

Thanks, Mike
Mike Christie

I think a thread like this was operating before? I have a GT also with the original hydraulic switch, which is still working. But with all the woes we are getting today with bad quality replacements burning out I am also considering alternatives before faced with the real emergency. As far as the swith, why not go to the mechanical ones that virtually all cars have now, LED lamps I think are good also, but quite directional, in the sense that not all can be viewed or seen from all angles?. whats the general responce? Mike
J.M. Doust

There was a thread on the midget board recently about LED brake lights and there reports about the varying amount of light from different types, as well as the angle of light output.

My brother's brake light switch recently failed on his GT. It appeared to be a fairly new item. I managed to find him a good secondhand original one.
Dave O'Neill2

What switches have you tried? I replaced mine early last year with an Intermotor item from the MGOC and that has been fine so far. Because of the reported problems with these, and mine being iffy just before a run I did fit a relay, but it packed up anyway. Originally I had intended to fit the relay with the new switch but then thought "Why should I?". If vendors are supplying inadequate parts they should be told and have to supply replacements.
PaulH Solihull

I have and am satisfied with leds. Having said that a relay is cheaper, and is very easy to wire up. Many leds sold for brake light purposes now are an array that helps make them less directional, than early ones
Michael Beswick

Ron Francis makes an uprated brake hydraulic brake light switch. It goes for around $30, but will last as long as the original units. My '67 still has the original unit. RAY
rjm RAY

So, excuse my ignorance but no comments were put forward for or against the use of a mechanical switch for the brake lamp activation. Indeed why is it that the hydraulic brake lamp switch eventually fails? Too much amperage through it?? or what. Mike
J.M. Doust

One argument against a mechanical switch is that it isn't just a straightforward replacement part.

Also, the replacement mechanical switches for the US (and later UK) dual-circuit brakes are just as unreliable, I am led to believe.
Dave O'Neill2

I'll second that, I went through about either three or four mechanical switches in 10 years before I gave up and fitted LEDs, my only comment on the them [which I think I've posted here before] is the intesity difference between tail lights and brake lights isn't as much as ordinary bulbs but as I very rarely drive the car in the dark it's not all that important.
Ron
R. Algie

The factory mechanical switch is a fiddle to fit, and seems to have as many problems, which are the contacts not up to the current they are required to carry. For years now these switches on modern cars simply operate a relay, which takes a lot less current than the lamps. If the contact material on our switches is the same i.e. not an OE design then that could well be the cause. However relays have their own problems of inductive emf arcs damaging the contacts, so a quench diode is needed. I don't know how switches on modern cars deal with this. OTOH maybe the troublesome switches are just cr@p.

The best mechanical alternative to the hydraulic seems to be a generic one that mounts under the firewall 'shelf' and replaces the brake pedal return spring as well - a screw-hole or two and away you go http://www.electricalcarservices.com/brake-light-switch-push-or-pull-ecs-d057951-p-1538.html
PaulH Solihull

Mike-
A load of only 30 mA should make your switches last. Click on this- http://www.autoelectricsupplies.co.uk/catagory/90
Stephen Strange

search the midget general archive for "Led test = disaster"
You will find the pics of the LED's there.
Onno K

Ohh, Thanks Mike
J.M. Doust

This thread was discussed between 13/01/2012 and 17/01/2012

MG MGB Technical index

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