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MG MGB Technical - Hydraulic Brake Light switches

With the help of a contact in the US, I have located a source of better quality hydraulic brake light switches. The current crop of switches (at about £6) have two separate but linked deficiencies. Firstly the pressure required to operate them is sufficiently high for the switch (and hence the lights) to operate only under “hard” braking. Secondly, and partially caused by this, the contacts do not close “hard and fast”. This leads to arcing and the build up of the resulting crud means yet more pressure is needed to operate the switch and lights.
The improved switch operates at about the same pressure as the OE did back when these things were properly made. This means that the pedal needs to be pressed less far down for the brake lights to come on. Furthermore, because it operates at a lower pressure the closing of the contacts is faster and harder. (However I shall still use the relay and diode I have fitted). There are indications that this switch is used in an OE application but as yet I have not found out what it is!

In an ideal world, a switch could be tested (and compared against the usual cheap offering). The alternative is for a bunch of us to buy one and try it. The results may not be wholly scientific but it should give a clear indication.

Bought singly, they are US$65 odd ( delivered including VAT and duty): In batches of 10 about US$45. Adding a jiffy bag and postage onwards in the UK (by me) it would be about £40. As yet I have not tried negotiating for bulk purchase or freight, so there may be a saving.

I’m prepared to buy them (in $) stand the exchange rate and post them on. Details of paying me can wait till I can gauge the level of interest.

There are no guarantees!

There are many “work-arounds” for this problem: each with their merits and problems. The purpose of this is to gauge the number of people interested in this particular possible solution
Michael Beswick

Just to clarify - "Adding a jiffy bag and postage onwards in the UK (by me) it would be about £40." - gets how many switches?
Nigel Atkins

One.
Michael Beswick

would also be worth posting this on the MGA and Midget BBS
Dominic Clancy

Thanks that's what I thought.

I'd be interested.

Dominic makes a good point about widening the potential.

Now for the points which you've probably already considered and just a little clarification so no one is confused (I used to order spare parts, not motor though, so I do have experience - which you also might have but I can't know this).

. As you've already put - there are no guarantees.

. The part is as an improved replacement to part number C16062(A)

(*in which case you can extend it to other makes and models)

. It might be a bit off putting that you will still be using your relay and diode with the new part - is that to save the bulbs, the switch, both or some other reason?

I'm not trying to put you off, only dealing with realities.

If you get sufficient interest I'd strongly recommend that you get all payments up front and specify that's there's no provision for cancelling the order at anytime (even with large deposits taken we had some parts were never collected so went to a very strict full payment up front).

Also what are you going to do if anyone gets a duff part?

Is there a way of fitting them wrong, or a preferred method (Guy on Midgets has a method, I've fitted at least 4 of these and used that method once and snatch fitted the others)?

Are you able to accept that if it works and is reported back on then one of the bigger suppliers may place an order to the US and sell them here for a much (much) lower price (*see also above), or the US supplier might contact them see a market, i.e. you do the work and prove the concept for them.

Nigel Atkins

Michael. Any potential you can post the seller in the US, so us in the US can order them? I have a relay on mine, but just this last week, had the brake lights not work.
Bruce Cunha

Bruce - If the relay that failed, is one that I did up for you, contact me at SUfuelpump@donobi.net and I will replace the relay for you. You might also want to check the brake light switch to see if that is the culprit.
Cheers,
DW DuBois

Bruce,
over here I'd also consider checking the bulbs as the quality of aftermarket bulbs for about the last 10 years that I can think of has been very poor. I've had bulbs fail straight out of the box or when stored in the boot for a number of years.

I saw a few years back "heavy duty" versions, I've never bought any but cynically wonder if they're just properly made versions of the standard versions. Also recently I bought some brake light bulbs for a friend and on the packet it actually had to "upgrade to rapid response" - "faster light up and greater intensity" but of course the shop didn't have any.

And on looking I've also found longer life bulbs.

standard - https://www.ringautomotive.com/en/product/r380

rapid response - https://www.ringautomotive.com/en/product/RW380RR

longer life - https://www.ringautomotive.com/en/product/RW380LL
Nigel Atkins

Bruce: no problem, can you email me on genesismb@aol.com.
You may also have some knowledge from people in the US about the supplier and even the part.
Michael Beswick

Nigel: all valid points but I was trying to keep this simple.

The purpose is to find about 10 people who are prepared to punt £40 in an effort to 1-help themselves;2-figure out if the switch does what it needs to and so help others. There are no guarantees as I said, and I am fully aware that most people will not pay more than the minimum, and others will wait till "others have gone first"

So yes it could be widened to Midgets As and so on but I'm not trying to take on a career in posting and packing. Also With just 10 there is some chance of feedback.

The switch's main claim to fame is the lower pressure at which it comes on. This should reduce arcing, as well as getting the brake lights on quicker. However I very much doubt the contacts of the switch are as good as OE ones from the 60's which were engineered to overcome arcing. There would be no market now as "replacement" switches are at £6. By keeping my relay /diode I am reducing arcing as far as I can. It might not be necessary, and might be regarded as not being a true test of the switch. I just want it to work.

Payment: I was going to cover this only when there is sufficient interest, but I won't place the order till I have all the money in. If people don't like that,or don't want to trust me, they don't need to play.

Fitting: let's leave that till we see the interest.

I have no interest in becoming a parts supplier. If a major player wants to-great. However they already have the option and have clearly decided the market is not there. If by doing this we create sufficient interest I shall be delighted.
Michael Beswick

Hi Michael,
thanks for your reply, I wasn't knocking you in fact I feel just the opposite, you're doing what the clubs should be doing.

I was thinking of going to the A, Midgets (Minis, Jags, etc.) not to increase the sales of jiffy envelopes or the coffers of the Royal Mail but to get to the 10 people you want and perhaps quicker. I might be wrong but I doubt you'll get 10 from just the B section here, I'd be very happy to be proved wrong.

If yourself or Bruce could get some USA testers that might/could provided enough information to decide whether it's worth your effort to proceed further.

I've literally just been kindly offered the chance to test a (£4) switch, my existing switch IIRC was from Brown & Gammons (ukmgparts) about (possibly) 5 years ago and works but I don't really know how quickly and how much pressure and have no formal testing equipment just my wife and I discussing our definitions of speed and pressure which based on decades of experience will differ.
Nigel Atkins

Dave. B is working fine. I will be installing one on the TD and would like a new one to start with.
Bruce Cunha

Nigel: You may well be right. Interest so far is minimal with nothing from those who complain about parts quality!

Bruce-you have mail
Michael Beswick

Michael, so far you've found what the clubs and suppliers would probably say - customers complain about parts quality, mainly between themselves but when offered an alternative part that costs more most still buy the cheaper part that some complain about.

If you're interested I'll let you know the result of my new switch compared to my existing modern made switch, the source isn't a secret as it's quoted on this site but I'd sooner test it before saying anything as I'm a magnet for car part problems that no one else ever seems to suffer, I recently had an electronic part that suffered because my engine bay had a 1 in 5,000 environment.
Nigel Atkins

Nigel.
Yes please with regards your new switch.
I think I can safely say that there is no interest is the switch I have found!
Michael Beswick

Bruce - Contact me at SUfuelpumps@donobi.net I can work a brake light relay/arc suppressor for you.
Cheers,
DW DuBois

Hi Micheal,
switch arrived today from a kind, fellow BBSer.

Lucas SMB423, green and white labelled plastic packet, Made in UK, week 28 of 1997.

I don't think I'll be able to test it until the weekend.
Nigel Atkins

I'd be interested to know how you get on with that in use. I sectioned one and it was basically the same internally as the rubbish ones from the usual sources, basically just a piece of metal pushed against two other pieces of metal to bridge them and make the contact.

The originally fitted type had a sprung contact that rubbed against a fixed contact to give a self-cleaning action. The problem with the 'simple' type is that they are not snap-action like many switches are, so unless the brakes are banged on, as they come together slowly just a very tiny area of metal makes the initial connection, which with the very high initial current of incandescent bulbs - a theoretical 48 amps no less, that initial contact is melted to leave a blackened area. As time goes by that blackened area grows, and takes more and more pressure from the brake fluid to force a connection through, delaying the brake lights coming on, and eventually under light braking they don't come on at all.

I'm intrigued as to why the pedal-operated switches don't have the same problem, when the only contact pressure is from the internal return spring.

The attached shows a 'new' switch that started delaying after just 3000 miles. The Lucas are slightly different in that, instead of relatively large surface areas being brought together which means only a small amount of burning will stop the connection, the Lucas has the disc pressed against the ends of two pieces, which in theory gives 'points' which should be better able to pierce the burning. Having said that I have seen pictures of that style of contact with the same burning. They were described as 'OE', but they aren't MGB OE.

I've had a relay on a 'rubbish' switch, and a tell-tale, for five years now with no delay in lighting up.


paulh4

Sadly, as it rather vindicates the suppliers opinion of their customers, there is insufficient interest to make this US sourced switch worthwhile.
Michael Beswick

I doubt that you would find many people willing to speculatively invest that much money in a switch, if they don't need one immediately.

If someone was in desperate need of a switch and they were offered a choice of a cheap switch which may last a year, or a much more expensive one which may last considerably longer, they may or may not go for the expensive one.

Just my two cents.
Dave O'Neill 2

Sadly I'm not surprised. I think it goes further than the relative very high cost of this particular switch.

There are now, and I think it's been the case for a number of years, more people that own more than one classic, many owners very rarely drive their classic(s) so parts quality and durability doesn't matter to them, this is on top of the attitude that many want the cheapest parts. For many years people have been told to buy classics as investments and that they're cheap to run and parts are cheap.

I will report back on my totally unscientific findings.
Nigel Atkins

Sorry I forgot to soak the fitted switch in PlusGas yesterday so Sod's Law it needed it - so sorry it won't get done today, possibly during the week or next weekend.

I'll refrain from whinging too much but I can't remember having to fart about so much last time (I've got a Midget), three toolboxes out this time and some dismantling but more tools and dismantling is required really - so I've given up, left the PlusGas to do it's stuff and I going to drive the car now instead of having my head under the bonnet and back aching (belly aching instead).
Nigel Atkins

Andy Tilney kindly sent me the switch - Lucas SMB423, green and white labelled plastic packet, Made in UK, week 28 of 1997. Andy tells me that the supplier has 12 left in stock, 8 with a date stamp for 1984 and 4 with a date stamp of 1999, they cost £4-00 plus P+P from LMS Lichfield.

(SMB423 brake light switch- Lucas) - http://www.lmslichfieldltd.com/

Andy says the switch he has from them works very well on his MGB and the switch he kindly sent me works well enough - but no better than the switch I've had fitted for 5 years, date stamped 48 /09 (Nov 2009).

On totally unscientific tests, car static, handbrake off, no servo fitted, I pressed the pedal a bit further with both switches further than I expected but not excessively hard or beyond the start point of brakes operating as far as I could tell.

I don't feel these switches are the rubbish type and my previous one dated 2009 has worked for 5 years so far and I'd expect the same from the switch Andy sent me.

Make of this what you will, any questions for me just ask, as you can tell I can be as untechnical as you want.

Nigel Atkins

Sorry I forgot to put -
Having fitted new drums and one with a high spot means perhaps I’ve not got the shoes as snugged up quite as much as with the previous better original type drums so that might add a little to the impression of pedal travel.
Nigel Atkins

Those 'Lucas' switches are slightly better in construction than the rubbish ones but still nowhere near as good as the originals. As in the attached the disc is pushed against the ends of two contacts rather than flat surfaces as in the earlier image, so hopefully 'points' will cut through any burning better. The contact material is also a separate piece riveted to each spade terminal, so hopefully better suited to electrical connection, and the disc may also be more suited to electrical connection that the other type, only time will tell.

Part 2 follows.


paulh4

These pictures show a similar switch to the Lucas, which has suffered significant burning and melting, needing more and more pressure to light the lamps. This is apparently an OE Bosch switch costing $20/£15. The complete document can be found here https://tinyurl.com/ycxd37l3

The problem is that for some years now most vehicle manufacturers have been using relays to light the lamps, so the switch does not need to be as sophisticated as the originals were with there sprung contacts incorporating a self-cleaning sliding action. And our switches have been cost-reduced to the same standards, which are unsuitable for our systems.


paulh4

I drove my wife's modern car last night and took note of when I could see the brake lights operate compared to pedal travel and pressure and it was more than I expected so perhaps I was being unrealistically strict with the Lucas switches, the difference wasn't that great and my wife's modern has a servo, and an alphabet of electronic aids.
Nigel Atkins

“...and my wife's modern has a servo, and an alphabet of electronic aids.”

Does it have a hydraulic switch?
Dave O'Neill 2

Didn't know Dave, I looked it up and it appears to be a pedal switch.
Nigel Atkins

Surely it has a pedal switch? If it does then the lights should definitely come on before any pressure is developed in the hydraulic system - don't be confused by the pedal return spring. In terms of pedal travel it should be significantly before the hydraulic system lights them as a typical mechanical plunger switch (push off rather than pull on) only has about 70 thou of travel.

However what car is it? Some French cars had braking systems that needed very little pedal movement or pressure to apply the brakes quite significantly, which caught people out who were new to that system and initially they braked far more severely than they intended.
paulh4

Hi Paul,
I can't see a switch so guess it's a pedal switch under some cover. The pedal certainly has travel before the brakes light up.

The car is the acceptable face of VW, a Skoda, Fabia, 2015 (sharper edges to bodywork).
Nigel Atkins

I'll have to look on my ZS, not something I'd thought about before. The book says 'brake pedal switch' which seems clear enough ... and it lights the lamps (incandescent plus a high-level) directly!
paulh4

Paul,
I've just checked again and there's definitely some pedal travel before the light are on (incandescent & h/l), engine running, handbrake on.
Nigel Atkins

There has to be some pedal travel for any switch, and for pedal switches it's likely to be close to the push-rod to the master and so more travel at the foot-pad than at the switch.

My ZS has about 15mm, the V8 with pedal switch 7mm, and the roadster with hydraulic 35mm. Pedal switches shouldn't need the engine running, and although with hydraulic switches and a servo it probably should but I didn't want to do that in the garage for such a short time, so with the engine running it could well be more than 35mm. I'm working on a bracket to mount a micro-switch for that which tests have shown should be about the same as for the V8.
paulh4

Sorry, I misunderstood your "lights the lamps (incandescent plus a high-level) directly!" to be instantly.

I only started the engine to cover all possibilities, the engine was already warm, we don't have a garage and it's a stop/start (start/stop?) so goes on and off in short spaces of time anyway (although my wife says she is going to disable the function for winter even though the system allows for engine warming and battery load).

I'd need three people to measure pedal travel to lights on.


Nigel Atkins

Fitted the roadster pedal switch, 9mm travel to light the lamps, which includes a few mm taking up the play in the push-rod assembly before it starts moving the master piston. Could be adjusted for less but that is before any pressure is developed, so no point really. Switch is rated at 15A and 120v so I'll see how it goes. I've left the hydraulic system in place, and the tell-tale, so I'll be able to see if the micro-switch starts giving problems.

There is a convenient bolt and welded nut securing the pedal box the other side of the stiffener to the pedal, one of six but that one is 5/16" whereas the others are 1/4". Just needed a longer screw, washers and nut. It doesn't look like it but there is clearance between the pedal and the switch bracket. The switch is the type with a springy finger operating the button, without that the bracket and switch would have to be positioned pretty carefully to ensure it opened when the pedal was released, but isn't hit when the pedal comes back which could prevent the master piston coming back as far as it needs to as well as damage the switch.


paulh4

I suppose you could just place a small pressure pad switch under the pedal rubber, hook up to a relay - then the light would work as soon as you applied the brake ....
Chris at Octarine Services

Oooo luverly

paulh4

Paul,
is that one of those octopus wires relay things -

and one of those Scotch slice connector things -

and only single crimps on the insulated connectors -

and the red wire insulation scuffed off -

all fire hazards, I'm on the phone to West Midland Fire Brigade now!

:)
Nigel Atkins

Lol - I bet it works though ....
Chris at Octarine Services

"If you liked that, you'll love this ..."

I must admit to having done this. On the eve of a long weekend away in Lincolnshire I wasn't happy about the 'new' hydraulic brake light switch. I could tell from the tell-tale (fitted because tales of poor replacement switches were legion by then) it was needing more pressure, so I wired in a switch under the dash. On the way back home it pretty-well stopped working altogether so each time I had to brake I used the manual switch. Eventually the Navigator noticed and asked what I was doing, and when I told her she wasn't impressed!


paulh4

I also had to do this when I was told by a very polite German lady on holiday last year, Entschuldigung, Sie bitte, aber Sie haben keine Bremslichter an Ihrem Auto, luckily I was able to conect my hidden fuel pump cut off switch into the brake light circuit, and use that for the return journey to britain
Andy Tilney

Paul I hope yours was on a momentary switch. :)

I was stopped by the Police in my Midget because he thought my brake lights weren't working - bloody hydraulic switch needed too harder push, I tend to feed my brakes in. I told him that I was running in and testing my new gearbox and clutch, which was a bit true, so I was using gears to slow up. I said I'd show him and asked him to watch my brake lights as pressed the pedal hard.

Obviously I changed that switch ASAP.
Nigel Atkins

Why not wire both switches in parallel, that way you have redundancy 😊

I’d considered building a warning light that would monitor the current when the lights were operated, it would go green if both bulbs were working, flash single red pulses if one bulb was out and double flashes if both were out, it would also have a buzzer as an alert if one or more were out.
R.A Davis

Nigel - no, things hadn't got that bad at the time that I forgot to turn it off :o)

RA - that is what I meant by "I've left the hydraulic system in place, and the tell-tale, so I'll be able to see if the micro-switch starts giving problems".

Amongst many other electrical gadgets I made a brake light failure warning circuit for our first car in about 1968. I was using reed relays in telecommunications at that time, if you pass a current through a wire wrapped round a reed insert the internal contact will close. And if you pass another current at the same level in the other direction through a second wire, the contact will open again, or not close if both are powered together. By feeding one bulb through one wire and the other bulb though the second wire, if both are working the contact remains open. But if one fails and the other is working the contact will close, and you can use that to light the warning lamp. Only a few turns of not very fine wire are needed, so there is no measurable reduction in current to the bulbs and hence their brightness is unaffected. You can use semi-conductors to sense the current, but by their very nature semi-conductors result in a forward volt-drop which can be almost a volt and reduces the current to the bulbs and hence their brightness.

That didn't warn if there was a break in the circuit before the wiring to the bulbs split, and to do that you really need two switches - the main one to operate the lamps, and a secondary switch to trigger the warning in case the circuit involving the main switch failed in any way.
paulh4

Paul

I looked at measuring the voltage drop across a small value resistor but the problem was either the voltage drop was very low or with a higher valve it was easier to measure but the voltage drop would affect the brightness so I decided to look at the ACS712. This has a resistance 1.2m ohms so the voltage drop would only be about 4mV.

I’d planned to use a small micro controller to monitor when the voltage was present and then use the ACS712 to measure the current, this would then light a bi coloured LED as appropriate. The buzzer would sound if it detected one or both lights were out. I thought it would probably also need a mute button that would silence it until the car was next started, the thought of driving for an hour or 2 with a buzzer sounding every time you braked didn’t appeal, although of course the real answer would be to replace the bulb.

https://www.sparkfun.com/datasheets/BreakoutBoards/0712.pdf

Bob
R.A Davis

Neat - the 21st century version of using magnetism, although the principle dates back to the 19th :o)

With any of these things introducing additional components and connections into the circuit also increases the possible points of failure. I wonder if a Hall-effect device would be sensitive enough to pick up the magnetism radiated by the existing wiring.

Or maybe heat detection at the bulbs ...
paulh4

“introducing additional components and connections into the circuit also increases the possible points of failure”

Absolutely correct, but the failure of any part of this system would at the least give you an indication of a problem. If the connections to sensor fail it would show up as 2 failed lights, if the supply to the processor or the pickup to indicate the brakes had operated fails it would show up by not giving a green indication.

I chose this method as the sensors and processors are cheap and come on pre-assembled boards that would only require a few additional components.

Using a Hall-effect sensor to pick up the current in a cable shouldn’t be a problem and I believe this is how some of the current clamp meters work, the problem is shielding it from adjacent cables which could also affect the ACS712 dependent on where it was positioned.
R.A Davis

I drove my wife's car last night on quite dark country roads and I was able to test pedal movement to lights coming on and them seemed to light up quicker than on my static test.

When I get a chance I'll also try in my Midget to see if I get the impression of the lights coming on with less pedal travel than on the static test and report back.

All totally subjective of course - still be more accurate than some scientific and research papers though.

Nigel Atkins

I don't see how you can determine anything like what is actually happening except by measuring the pedal travel needed. If static and dynamic i.e. vehicle movement did give different results then it would be erratic and hence potentially fail altogether at some point.
paulh4

Paul,
that means I should expect failure of the switch on my wife's modern 3 year old car, and I do, but whether that's within the life of the car or her ownership is another matter. Her last car was sold, prematurely 9 years from new, gwad bless GM Vauxhall, but we're hoping the Czechs can do better despite their German ownership (German engineering quality is very much over-hyped especially by owners or those trying to sell their products).

As for the brake switch testing equipment, it is of the lowest order, my brain and my perceptions, but I'm very happy to take you out whilst I operate the brake pedal and you lean into the footwell with a tape measure. As you may not be used to the movement on the road of a Spridget I'm happy to drive your B or BGT V8 instead. I know where Solihull is and can be there within a hour, just let me know. :)
Nigel Atkins

"I should expect failure of the switch on my wife's modern 3 year old car"

I wouldn't. The one on my 14 year-old ZS is original and I wouldn't mind betting the one on my 42 year-old Z8 - 24 years on my ownership - is as well. The difference is that those - and I'd put money on your wife's being the same - are pedal operated switches. Has anyone had a pedal-operated switch on an MGB fail? Original or replacement? Accounts and personal experience of failures of modern hydraulic switches are legion and have been so for years. There must have been a failure of a pedal-operated switch SOMEwhere, but I've never heard of one.

The point I was making about measuring pedal movement for the brake lights to come on is that you shouldn't have to be driving the car to do it. Although you probably would need the engine to be running on cars with a servo. How would driving it be different to it being stationary?
paulh4

US cars had pedal operated switches from 1968, I believe. There are plenty of stories of poor quality replacements on the Midget BBS, which presumably means that the originals have also failed.
Dave O'Neill 2

I understand Moss USA had pedal operated switches re-manufactured to a higher spec. But as to when and why I have no more info.
Michael Beswick

Dave: From the start of the Mk2 in 1967. Originally on the front of the pedal cover the same as the UK single-circuit rubber bumper cars, then on the back of the pedal box on all cars when they got the boosted dual circuit system. That was different times for different markets, but the switch stayed the same.

Midget BBS here? Can only find one reference to the pedal switch having fallen apart. All of the others relate to the hydraulic switch.
paulh4

Paul,
I meant I expect the switch to outlast the car, it's only tight-fisted classic car owners that want the cheapest parts available that rarely use their classics that accepts parts that last days or less rather than lasting decades.

Modern made pedal switches falling apart or exploding goes back at least 12 years as I had it when I owned a Triumph GT6 and I've seen others post with the same problem and some with solutions. There'd be more than one post on the subject from me alone, try a search using something like - 'brake pedal switch falling apart exploding' - you could add 'GT6' to that for some of my posts. Thinking about it you could add 'tight-fisted classic car owners parts' for more.

I get problems with even usually well made parts, I'm a magnet for them, had a couple just recently and expect more from poorly made parts soon.
Nigel Atkins

Doh, realised I looked on the MGOC archive rather than here ... and that's where the problems started.

Trying to open another tab with the Midget BBS told me I wasn't logged in.

Then trying to go back to the MGB subject that told me I wasn't logged in either.

It's years since I've had to log in as I use a link on the bookmarks bar, so had to request my username and password.

When I got that I could log in, but then had to delete the old bookmarks bar link and save the new URL before it would go back to logging me in automatically.

Any road up as they say round here. Looked at loads of Midget threads on brake light switches and most of then refer to problems with the hydraulic switch, although one of those does have you, Nigel, saying you had a mechanical one on a Mini 'explode'. There are a few about the pedal switch, most with Dave Dubois saying the replacements in America are crap, which is presumably why Moss US have sourced their own.

I don't remember any from the UK complaining about the pedal switch, and if the US ones have been ... well, US, then I'm surprised the same complaints haven't cropped up with MGBs.
paulh4

Paul,
I think this site was getting a maintenance as it went funny, sent me to an error page and then I got the site back but resized zoom, all within a few minutes and then back to normal.

I don't think my post would be about a Mini as when I owned a Rover Mini 1.3i (6 months old bought on impulse and another car industry story of mine) my wife refused to drive it on her 300 miles a week commute to work and instead used my RV8 B roadster conversion. So we didn't have the Mini many months and never had trouble with the brake switch, the GT6 was the opposite loads of issues including exploding pedal brake switch, more than once.

I'll look tonight for you and find some posts on the subject on the Midget side.
Nigel Atkins

Paul,
many apologises to you, I was wrong - three times.

Firstly I was referring to the wrong switch, now I see where the Mini bit comes in as theses 13H3735 are fitted to Minis, it made me laugh to think of these piss-poorly modern made switches also being fitted to Bentleys and RRs.-
http://www.leacyclassics.com/13h3735.html

Second I couldn't find the references in the Midget section to these switches failing and exploding, even my own posts, but I know I've put some and so have others, but no proof to give now.

Third, an admission, I thought the 13H3735 switches were fitted to the Midget 1500 and now see they weren't.


Nigel Atkins

BHA4675 for the later MGBs, and Midgets I understand. Significantly more than 50% of MGBs used this switch, but a tiny fraction of the complaints of failure. What there are seem to be down to the electrical end flying out of the metal can on replacement switches as the crimps are nowhere near as positive as the originals.
paulh4

Same thing on those plastic 'Mini' switches, the spring is stronger than the prongs that hold the two pieces of the main body together so they literally explode apart.
Nigel Atkins

The classic Triumph enthusiasts are promoting on Facebook an alternative mechanical switch for TR6, Vitesse, etc. It has the part number FAE24150 and fits all manner of modern European cars. It seems to have a metal body and be of better construction than the rubbish often sold for MGs. If it fits old Triumphs, it could well fit old MGs too.
Mike Howlett

Bet it's metric thread ...

Supplied with two nuts so I suspect it fits a plain bracket, needing access to the plunger side to fit/tighten the nut. You would have to remove the pedal cover to do that on ours, and adjustment would be a bit of a pain.

Long plunger too, so potentially needing quite a bit of pedal movement. The 'standard' ones err the other way if anything - there is only one and a half turns of the switch between just putting the lights out and stopping the pedal coming back all the way.
paulh4

Why not fit a switch under the dash at the brake pedal that works with a relay to activate the brake lights as soon as the pedal moves away from the rest position (this can be set up to light the brake lights before any pressure has been put on the pedal too). This would make access easy, and in a sheltered place would have a long life. This is how many brake switches on moderns work, the switch has to mounted to be in contact with pedal shaft below the pivot point. Then any switch can be used with modern manufacturing quality instead of the cr3p that is offered as classic car parts.

Example from Honda attached - there's plenty similar and good mounting points available under the dash for a rigid switch mount


Dominic Clancy

"Here's one I made earlier".

A handy pedal box screw right by the stiffener by the brake pedal - may need a longer one as mine did.

Simple bracket - I chose to curl mine round the flange on the bottom of the stiffener but it doesn't really need it, a right-angle will be fine if the upper bend is set such that as the nut is tightened the side of the bracket is pressed against the side of the stiffener.

Microswitch with a normally closed contact such as these https://www.ebay.co.uk/itm/262558420165

Wired in parallel with the existing hydraulic switch keeps the existing switch as a backstop. Mine already has a relay on it so I've connected it to the green and green/purple rather than directly to the switch i.e. the microswitch is powering the lamps directly.

Because of past problems I fitted a tell-tale so can see when the circuit closes, and will be able to tell if the microswitch can't handle the current. However the hydraulic switches fail as they are not able to handle the inrush currents of incandescent lamps with their 'slow close' design, these microswitches are 'snap-action' so I'm not expecting the same problem.

If you use an OEM pedal-operated switch - either off a modern car or as used on later MGBs - you shouldn't need a relay as they are not used with them and they don't have the same problem that the hydraulic switches do.



paulh4

This thread was discussed between 19/09/2018 and 23/10/2018

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