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MG MGB Technical - modern alternator wiring

I want to replace the alternator on an 80 MGB with a single wire GMC alternator.

How do I deal with the three wire Lucas harness?

I have the same GMC alternator on my 67 B and it's faultless, cheap and spares are everywhere.

All & any help appreciated.
Stewart
R.S.C Caskie

You might want to rethink that choice. I would recommend taking a look around the internet (Google maybe?) and see what other's experience's have been. There are other choices which frankly involve less hassles for your 1980 car than going to the old GM 10Si alternator from the speed shop. Take a look at what this man has to offer at his site: http://www.onefastmgb.com/pages/6/index.htm .
Bob Muenchausen

Is it really a one wire? If so presumably you then lose the charge failure warning light, which is a retrograde step in my opinion. You can fit a voltmeter I suppose, but there are easier options for getting an alternator which is cheap and with plentiful spares which keeps the warning light and doesn't need a voltmeter.
Paul Hunt 2

Delco Remy 96 amp will also fit, and you can keep the Ignition charging light.
K Harris

Having just recentley changed from the old 10/12 SI delco alternator to the more modern CS130 or "The Saturn Alternator", I would use the Saturn one.

Do we need the extra power? No, but the mounting is just like the stock Lucas mounting. With the older Delco, you will have to fabricate mounting brackets. The Saturn also has the advantage of keeping the idiot light.

Jayme
77MGB
Jayme

I would second Paul's question: is it really a one wire? Sadly, most people think ALL GM alternators are one wire, because of the single large terminal on the back. This is not true. Unless you paid a premium to get a one-wire (which is a standard 3-wire that has been modified, you have a three wire). It's unfortunate that this confusion still exists.

One-wire vs three-wire: On an MGB, there is absolutely no reason for using a one-wire. You gain nothing, you pay more, and you get less. The two wires you lose by going to a one-wire have to be dealt with, as you have found out, so why not use them and retain you alternator warning light? It's just as easy to do as it is to get rid of them.

GM vs others: The advantages of the GM is that it is readily available in just about any town of any size, so getting a replacement on the road is no problem, and they are a lot cheaper than some of the others. The advantages of some of the others are ease of mounting, ease of wiring, and less of a problem with mounting ears breaking, as has been reported with the GM (although in several thousand miles I've had no trouble with the GM).

If you want to use a three-wire GM alternator, and need to convert your Lucas wiring, connect the large brown to the lug on the back, the small brown to terminal 2 (sometimes called "F")in the small connectors on the side, and the brown/yellow to terminal 1 (sometimes called "R").
Dan Masters

This thread was discussed between 23/07/2006 and 03/08/2006

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