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MG MGB Technical - LED Bulbs

Hi All
Anyone tried these LED stop/rear light bulbs off Ebay [or wherever] I wondered if their low current usage would help the brake light switch last a bit longer.
Ron
R. Algie

I would suggest that a relay be installed. It takes the load off the actual switch.
Sandy
SANDY SANDERS

I am with Sandy. I don't believe that LED replacements are not yet designed to give the proper angle of coverage. For instructions on making a relay/arc suppression circuit to protect the rather wimpy replacement brake light switches available today, see the article, Brake Light Relay in the Other Tech Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/ The other alternative is to order one of the heavy duty (and heavy price) switches (P/N SW-32) from the Ron Francis Wiring at: http://www.ronfrancis.com/ Cheers - Dave
David DuBois

I have them. ultraleds.co.uk or .com -can't remember which. Low current so less of a problem for the brake light switch. they are good!
Previously I had a relay and halogen lights- bit hot!!
Michael Beswick

FWIW LED after-market external (at least) lamps are not road-legal in the UK. At least they still weren't when I last looked a couple of weeks ago, but I can't see that mentioned on the site below today. Usually it says something like 'for show and off-road use only'.

There are various LED arrays, this one http://www.ultraleds.co.uk/u38220r-ultra-high-power-single-wide-angle-p-1326.html?osCsid=b293bd0ea5bdab736e2fbe8b64f644b6 (top of page) probably is wide-angle enough as it has the array around the cylinder shining onto the reflector as well as on the end shining straight back. However the reflector is designed to focus light from pretty-much a central point, with the cylinder array being spread over a much larger surface area the effect is probably to *increase* the angle of radiated light, i.e. reduce the focus to following drivers. Any plug-in array is going to be something of a compromise I reckon. Given the questionable legality it's probably better to fit the quenched relay, although I have heard of Bosch switches fitting the *hydraulic* fitting of the MGB, albeit with different connectors.
PaulH Solihull

I purchased some LED bulbs, albeit cheaper versions than Ultraleds, having tried these I've reverted back to the original bulbs as I didn’t consider the light output to be sufficient, probably for the reason mentioned by Paul. I'd like to be able to use LEDs as I believe they have a safety advantage because they come on instantly and attract the driver behind's attention quicker.
Bob Davis

I have changed my instrument lights to LED. Noticeable difference in output, HOWEVER...the charge light now will not go off until the engine is revved, probably to do with the current carried by the led being that much lower. I must get round to loading the circuit to emulate the filament lamp (or change that one back to standard!)
Pat Gregory

There is no benefit in changing the ignition warning light and main-beam warning light to LED that I can see, especially if you have to add a bypass resistor to the former in order to get the alternator to start charging when it should i.e. by about 900-1000 rpm! Incidentally, early schematics *do* show such a bypass resistor, which would protect against bulb failure, but don't give a value. Having said that I have *never* had an ignition warning light bulb fail in over 40 years! Probably why the bypass resistor was dropped, if it was ever provided. There *is* a slight benefit in changing the gauge illumination lights to LED as some types do result in brighter gauges, but you lose the function of the rheostat (hardly a loss ...).
PaulH Solihull

Paul, I can understand what you mean about loss of rheostat not be much of loss but if you get the chance on a very dark road to turn the dash lights off you should give it a try, it's spooky.
Bob Davis

Hi All
I've now fitted a couple of stop/tail LED bulbs, they are the type with 18 red LEDs, 6 of which point tangentially.
I did a comparison in a darkened garage while changing over, the tail light is slightly brighter on the LED bulb but slightly less bright on the brake light, tangentially the LED is slightly poorer but I'm not sure if this is all that important as the MG has quite good rear lights in that respect compared to say my TR6 which has almost no tangential light at all by design.
The LED does come on noticably quicker but I would say the jury's out, particularly if they are not road legal, I'm also a bit disappointed that the brake light is slightly less bright, it's not by much but they're not really all that bright in the first place compared to a modern car.
I would prefer not to install relays and more wiring etc as it's something else to go wrong, I would be more likely to look into fitting a better quality switch.
I'm on my 3rd or 4th brake light switch in 15 years, it's the later mechanical type, I'm still on the original TR6 switch after 8 years, unfortunately they are not easily interchangeable.
Ron
R. Algie

In a photo comparison of tail and brake lights I saw quite a few years ago, both (American sourced) LEDs were brighter than the old incandescent (which could have been down to old bulbs and dirty reflectors) but the biggest problem I saw was that the tails were quite a lot brighter, which reduced the differential between tail and brake lights, which makes the application of brakes *less* visible than before. The other thing is the bright tail lights are not friendly to following drivers in the wet.
PaulH Solihull

This thread was discussed between 05/10/2010 and 09/10/2010

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