I pulled up at a likely looking garage sale on my way to Tumut today. The guy had some old bits of cars, so I thought their may be a mini bit too.

There wasn't anything special to be honest, apart from what looks like a brand new 8TR regulator which anyone who owns a post 69 to 71 Mini will know as the external regulator for the early alternators. Usually blown and diabolical to find as well. This one came in a little Lucas Box which fell to bits. It does have screw marks though... Works fine too.

Its nice to find rare early mini, Cooper S and GT stuff, but every now and then a little gem like this is good to find as well.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Good score Mick , definately a case of being in the right place at the right time .

Nice find.

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1963 Morris 850 Smoke Grey
1963 Morris 850 Shadow Blue
1965 Morris Mini Smooth Van
1966 Morris Mini Van
1969 Morris Mini Deluxe Resto
5/72 Clubman Gt

but the terminals look unmolested so may have been factory tested (only)

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"Show me the Mini!"

Mick - does it have a part number (8 digits) and date embossed on it?

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

It does.
062938104A 10 70

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

How do you test them I have a couple I need to check.

That's the correct one for BMC cars according to the Lucas Australia catalogue. There's other models of 8TR that aren't appropriate.

By the way, that first character of the part number is not a zero but some sort of trade or other mark, like a Mercedes three-star mark.

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

Me too.

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

I plug them in to replace a known working 8TR and test the alternator output under charge (simulate a low battery after a fair whack of engine cranking) and then later test the final charge voltage.

A full test would need a signal generator to provide an input voltage, and an oscilloscope to track the 8TR output response. A full test rig would have a resistor bank to sink the alternator's output current into as well.

Handy to know would be the expected factory fresh 8TR response curve to a rising input voltage, but this can be reasonably extrapolated from a known good 8TR.

I've seen some with a small pot on the back to trim the curve a little. This later one doesn't have the little trim adjuster.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Was it just 69-71 for this type of alternator & external reg? Were they generators before that?

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Spot on! The alternator was introduced with the Mk II Mini series in 1969. Initially the 8TR regulator like Mick's was used, then a 4TR (larger black plastic box). Then the regulator was integrated with the alternator. All were Lucas Australia products. The change from generator to alternator also meant a change from positive earth to negative earth.

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

Ta! For some reason I thought they swapped to an alternator earlier.

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I believe there were three alternators or maybe four before Mini production ended. After generators was this one with the external reg coming first, and all alloy internal reg second, then the later 17 or 18ACRs. I haven't got anything to refer to from where I am however...

Good to see you online again Scott

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Are you sure this is correct? Probably is but first I have heard of it...

I suppose that would make sense according to the stickers in early clubman boots "warning this is negative earth"

My moke has a generator and Is negative earth and I assumed to wiring had not been changed. But now assuming it has

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