MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Hot white ignition wire

I have a 1973 MGB/GT and I noticed that the white ignition wire running into the column and switch was rather warm to the touch. Is this normal? I was trying to get my tach. and turn signals working from setting in Humid fl.. weather. I am running an updated bits 4 brits spade fuse panel with 3 relays.

Ben
B Stone

Ben - they made a batch of switches a few years back with wires that are too thin and which could get warm. If the 3rd fuse is also hot, you may have a prob on one of the green lines and I would suspect the indicator circuits but with your relay setup the prob may be elsewhere - Is the white wire feeding the relay circuit via terminal 30 ?
Roger Walker

If it's getting warm it's carrying more current than it should, or there are bad connections nearby which are heating up and transferring to the wiring.

The white wire feeds a number of unfused circuits such as the fuel pump and overdrive, and both have been known to go short-circuit causing harness damage, and for that reason I've fused both mine.

This is one of the few occasions where an ammeter would be used, to check if the cause is excess current, and track down where it is coming from by disconnecting various parts of the circuit.

The coil is also fed by the white wire, and as a 73 if you have fitted a 6v coil intended for rubber bumper cars to your 73 that would draw double the current it should do. Take the wiring off the spades and measure the resistance of the primary. Should be 2.5 to 3 ohms on your car, if it's less than 2 ohms it is the wrong coil.
paulh4

Had a bad relay on the white circuit. Everything working again. The little needle trouble light with the alligator clip is so handy. Thanks for the help.
B Stone

It's a lesson for us all - Relays are not like puppies - they are not for life.
Roger Walker

A PO mod I presume, a 73 would only have a starter relay which isn't on the white. I'm also interested to know how that was diagnosed with a test-lamp.
paulh4

Had this issue on a 78 GT last week
Doing a v8 conversion with a mate, i'd done all the wiring for it and bound it all up in some very nice fabric tape, -looking good, time for a startup, hooked the battery up and no ignition light wipers etc, nothing coming out of the power relay with a test light, it was clicking but not contacting-
Gave it a little tap in case it was just a temporary thing and zooot, big smoke, sizzled the loom from the ignition switch through to the relay
The relay had fell apart inside and shorted to earth
William Revit

Willy,

If that relay was a new item for the conversion it would be nice to know the supplier and maker. A lot of people are, today, adding relays across the classic car domain.

Regards
Roger
R Taylor

I think the relays give a false sense of modern day electric reliability. Yes they do go bad. Used the test light to make sure I had power to the proper fuse and it was going thru, followed the trail. Power going into relay but not coming out. Like a lot of products today the quality of the relays are all over the chart. What is really scary is when the brake light relay fails ( twice in last 6 years).So now pre-drive check is always the brake lights.
B Stone

We resist the designer label ( should we all drive mercedes ?) BUT sometimes the designer label includes real quality control. I wish I could say "Lucas" but logic says "Bosch". ...
on the other side of the pond there may be an equivalent...... so long as its American !
Roger Walker

'Lucas' now is nothing more than someone who has parts made abroad the same as everyone else. I've had three indicator flasher units that were actually hazard units internally i.e. there was a delay between moving the stalk and the lights coming on, and they didn't indicate corner failure as they should. Contacted Lucas and they said "We haven't had any reports ..."
paulh4

Yes, learned that Lucas crap trap a few years ago called the supplier out to no avail. The green lucas stuff means thinner metal, contacts, thinner wire gauge, crimped not soldiered maybe won't work right out of the box, just Chinese crap in a Lucas box. Junk waiting to fail so you can replace it again. So old Red box Lucas is the good stuff I have learned. If a company sells the license to produce the product can't it be held to the same standard and quality?
B Stone

Patently not. There is someone out there - http://www.lucasclassic.com/ - that claims:

"Lucas Classic parts are often reproduced from original tooling or, when this is not available, from exact replicas of the products we made 50 years ago or more.

"With Lucas parts, you can expect exact bolt for bolt fit and take pride in the knowledge that you have chosen a part of outstanding quality that keeps your car or motorcycle genuinely true to the original."

With no product information or even who are where in the world they are. I think they had a stand at the UK Classic Car show a year or two ago and said more information would be coming available, but to me eyes the web site looks exactly the same as before.
paulh4

Green box Lucas is (still?) a brand of Elta (in UK and Europe) -
"ELTA Automotive are proud to be the official Lucas Licensee for Driving Vision and Switchgear throughout the UK and Europe."
"ELTA are a proud licensee of the iconic Lucas Electrical brand . . .".

The few products I've seen have a made in India or China look about them.

Links on the site don't all seem to work for me so things might be changed or changing, or just my computer. - https://www.eltaeurope.com/lucas-bulbs-wipers-switchgear/

(Elta) Classic Car Electrical and Lighting - https://www.eltaeurope.com/classic-car-electrical-parts/
Nigel Atkins

'Licencee' - that's the point. They have the right to use the name and imagery, and can get parts made wherever they like. Their UK base is just a few miles from me and consists simply of a warehouse and offices, no manufacturing.
paulh4

This thread was discussed between 27/09/2020 and 14/10/2020

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.