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MG Midget and Sprite Technical - Mechanical Brake Light Switch

Hi,

After what I shall only call "a bit of an electrical issue", I need a new mechanical brake light switch. The replacement ones I have seen all seem a bit, well, crap.

Does anyone know of a good alternative, or do I just have to bite the bullet (connector) and pay 10 quid or so for the one that looks like it'll last about 2 minutes.

Thanks,
Philip Dodd

Fit a relay and then the switch only carries a tiny current and should last for ages. That's what I have done. I've actually got 5 relays on my midget.
Mike Howlett


I recall that there was an article in Mascot involving surgery on new & old stock & how the contacts were made. Current ones were woeful & subject of early burnout.

New switch plus relay is a simple solution & had no problems since fitted last year.

Originals are like hen's teeth I believe.

Gavin Rowles

Thanks for the feedback - now you mention it I do recall something in Mascot.

Anything I should know/be wary about if I try and fit a relay? I'm not the most electrically minded (though I add that I do not think I am the cause of the electrical issue I mentioned...).
Philip Dodd

See the article, Brake light Relay in the Other Tech Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/ Cheers - Dave
Daved DuBois

BTW - the 0.47uF capacitor across the switch will cut down arcing (in the sme way if does for the points) and this should help extend the switch service life.

A
Anthony Cutler

There was an article by Dr J.E.Davies in Midget & Sprite Club magazine Mascot June 2011
Alan
Alan Anstead

Thank you all for the useful feedback.

I'll go down the relay route. Dave - I had found your very insightful page, though I have to admit that I was planning on leaving out the capacitor.
Philip Dodd

Sorry for being a dummy here, but according to your vehicle profile, your car is a '73 chrome bumper version. Shouldn't it be a hydraulic switch? Weren't the mechanical ones introduced with the rubber versions post '75?
Lawrence Slater

It's a US spec LHD, and has dual circuit brakes with a mechanical switch. I believe the US cars had a dual circuit system and mechanical switch quite a while before the domestic market got them with the 1500 (Moss US list the hydraulic switch for only 1967 models, the mechanical switch for '68 onwards).
Philip Dodd

I understand that if the modern switches have poor connectors that 'burn' out quickly a relay will help

but

is it more the case (or in addition) that they are so poorly made they spring apart with use - because that what I found the problem was when I had to use them on my Triumph, fitting a relay wont solve that problem
Nigel Atkins

Ah, I hadn't realised about the US spec having that system. Could you retro fit a hydraulic switch? They seem to be bullet proof going by how long they last.
Lawrence Slater

sorry Lawrence but the modern hydraulic switchs can be unreliable too, I've had two on my present Midget that only worked when the brake pedal was pushed hard and I had one moderen one do the same on the 70s Rover I had whereas a NOS Rover part worked fine
Nigel Atkins

My brother suffered brake light switch failure on his B. It appeared to be a modern replacement.

I acquired a good used original switch and it is working fine.

Another reason that I keep lots of secondhand parts, as well as any NOS that I come across.
Dave O'Neill2

the current stock may be OK as I'm going back a couple of years

the problem is when you test them they appear to work OK because on the tests you normally push the pedal harder
Nigel Atkins

Crazy ain't it? Stuff made 50+ years ago, is superior to stuff made today.
Lawrence Slater

I'm on switch#3 on my hydraulic system.

Hence I'm also on brake light relay#1.

Modern ones "seem to be" utter rubbish


[there, all bets hedged]

I have a couple of 0.47μF caps around somewhere, best stick one across the switching terminals huh?
Bill1

A warning about hydraulic brake light switches: We had a Lucas branded one fail earlier this year in a customer's car - but the failure wasn't the normal switch-don't-work variety, rather it was one in which fluid escaped. Result was a large spurt of fluid across the engine bay and instant loss of brakes.

Scary!

Fortunately it occured when the car was being parked, so no damage done other than to engine bay paintwork.

We binned the remainder of our stock of switches (40 of them) as a result and re-sourced to a different brand.
Paul Walbran

Both of my failed ones were in "branded" Lucas boxes

Green they were!
Bill1

Paul

Which brand have you switched to? (pun intended)
Dave O'Neill2

I went through several hydraulic switches which only worked under hard braking and only lasted a few years.

However, touch wood, I seem to have found one that works properly and lasts. I think it was the pattern brand that comes in red boxes.
Jeremy Cogman

FWIW I modified my pedal box to take a common mechanical switch from a popular Japanese car, end of story, no more problems buy the switch at the local parts store for $7.99 if it ever fails, no relay or cap needed.BTW a relay is something else to fail an added complication if you like.
Cheers
Rod
R W Bowers

Intermotor at the moment, they are more expensive but we seem to get least claims from them.

It's intriguing just how much less some of the things round now last compared with original. Cooling system hoses is another that spring to mind. I know the wisdom now is to use silicone hoses, but originally you'd get years of good service out of OEM hoses. And they were made correctly too.

Paul Walbran

doooooooooon't get me going on rubbish rubber

some of the electrical stuff seems to have come through the bad quality, whether they lasts 30-40+ years like the originals is a different matter

indicator units seemed to go through a bad patch, I've used a couple of s/h units but now have swapped to electronic - so if anyone needs an original unit
Nigel Atkins

more than words can say, susuki cheap reliable

Flip


Flip Brühl

If the lucas hydraulic switches are rubbish these days, then I would guess Flip has the answer. Use a Jap or German replacement hydraulic switch. All that's needed is a thread adapter.
Lawrence Slater

Flip's Suzuki switch appears to be mechanical...motorcycle?
Dave O'Neill2




I did hear that a brake light switch for a certain model of Harley Davidson motor cycle was a straight swop for a Spridget but never followed it up.


Alan Anstead

This thread was discussed between 15/10/2012 and 20/10/2012

MG Midget and Sprite Technical index

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