9 replies to this topic

[mini|inim]

Hey guys

My generator stopped working so I guess now is better time than ever to swap to an alternator.

Are there any problems in doing this.

Can anyone give any wiring diagrams or tips about doing this.

Any help would be appreciated

Cheers

[lrostoke]

Not done it on a mini, but did my Landrover a few years ago.

Just checked wiring diagram in Haynes as long as colours match should be following.

On the regulator box. Disconnect the Brown/Green and Brown and and Brown/Blue and join them

Brown/Green from generator is the main charge wire
Brown is a perminant live from the battery
Brown/Blue is the light switch feed

Brown/Yellow is the ignition warning light this can stay connected

I'd also use the extra large spade connector on the alternator to run a new 30 amp cable to the battery terminal on the solenoid.

As for the bracket required not sure made my own for the Landrover.

[mini|inim]

Sweet.

Doesn't sound too hard. I'll have a go and see what happens

Thanks

[dklawson]

There are a few other things to be careful about.

First and foremost look at your car and determine if it is currently positive or negative earth.
Take note of whether you have a mechanical or electric fuel pump.
Also note any other aftermarket electronics you have (tachometer, radio, etc).
If your car is positive earth and you have aftermarket accessories or an electric fuel pump there are additional conversion steps that must be followed for those components. You do NOT have to change things like the starter wiring, or "normal" Smiths gauge wiring. They do not care what polarity the car is.

Mechanically you will want the alternator bracket from a late A-series (not A+) engine. This bracket will be a long version of the one on your car. It is longer to take up the distance for the shorter alternator housing.

Assuming your car is already negative earth you will not have any wiring conversions to undertake. The most abbreviated description of the conversion is that you look at the old control box. You remove and join the LARGE wires together and insulate them from the car's chassis. You then disconnect and join the small wires on the control box (EXCLUDING THE BLACK EARTH WIRE !!!). You insulate those wires so they do not touch earth. At the alternator, you put the large generator wire on one of the two large spade lugs. You put the smaller brown/yellow wire on the alternator's small spade lug. Finally, with the higher output of the alternator you run an additional heavy gauge wire from the alternator's remaining large spade lug to the "hot" side of the starter solenoid (the side with all the brown wires on it).

There is a method I prefer MUCH more than cutting the harness to make this conversion. You can take an old control box, gut it to remove all the relays, then use very heavy gauge wire to solder the big terminals together, then the small terminals together. The gutted control box then functions as a junction box to which you leave all the original wires hooked up in their original positions (EXCLUDING THE BLACK EARTH WIRE !!!!). Leave the earth wire off of the control box.

More information is available at the Mini Mania tech section:
http://www.minimania...17/ArticleV.cfm
http://www.minimania...28/ArticleV.cfm
http://www.minimania...20/ArticleV.cfm

[mini|inim]

Thanks. That was very helpful! I think I will go for the junction box as it sounds like it will be much better than chopping and joining wires together.

My car is negative earth so should be fine. Would any Lucas alternator work? I have a 275 in my mini and am looking at:

http://www.trademe.c...px?id=378519699
and
http://www.trademe.c...px?id=377493369

at the moment. Do you think they will fit the bill?

[dklawson]

Oh yes... those alternators would work. However, since you are making this conversion... there are other alternators you may wish to consider. I would Google and do some reading on other possible swaps. Look for what has been used on other A-series and B-series engined cars. (Midgets, Sprites, MGB, etc).

You posted eBay links for New Zealand. If that's where you are, consider looking for alternators used on more local cars like Holdens or perhaps something Japanese (Denso?). Some Bosch alternators are very good, reliable units. For example, on my Mini I have a Motorola alternator that is a Bosch copy. On my Triumph GT6 I have a Delco (GM) alternator. The Delco alternator is so common here that I bought one rebuilt from the local parts store for $45 and it has a lifetime warranty.

The only magic on choosing your alternator is selecting one that fits the available space and finding one with simple wiring (again... Google will tell you what others have done). The advantage to choosing something other than Lucas is that you often find like I did that there is a more readily available alternative for a lower initial investment.

[mini|inim]

Sweet. Well I will do some reading, but might get the cheap Lucas for now just to get the car on the road and then sort out a better one once that dies or I need more power.

Cheers for the help it has been awesome

[mini|inim]

Ok so I have an alternator, but it only has 3 wires, one thick solid brown wire, one thinner brown and blue, and the same thickness as the brown and blue which is brown and yellow. Do I run a wire for the thick one to the fuse block and connect the other two and put them onto the starter?

Thanks again...

[dklawson]

I really cannot comment about the colors in the alternator plug you have. It may not be original. However, the terminal sizes on the alternator should be "standard" and to summarize them briefly, the two large alternator terminals are current outputs that get connected to the hot side of the battery (indirectly) and the small terminal is for the warning lamp connection.

Were this me... I would mount the alternator and plug the existing dynamo wiring up to the alternator directly (without a special plug).

I am confused by the alternator wire sizes and colors you mention. The alternator plug should have two LARGE wires/cables and one small one. Look carefully at the terminals on the alternator, not so much the size of the wires themselves. Below I refer to large and small alternator terminals.

Let's assume you are going to use the original dynamo wiring. The dynamo should have had two wires on it, one LARGE brown wire and one small brown/green wire. The big brown wire should plug onto either of the LARGE terminals on the alternator. The brown/green wire should plug onto the small terminal on the alternator. When you convert your old control box (OR splice the wires together where the control box was) the small brown/green wire is joined to the small brown/yellow wire in your car's original wiring and becomes a connection for the charge warning light. The big brown wire goes off to the fuse box and is the primary current feed from the alternator to the car.

That leaves you one open terminal on the alternator. As mentioned above... that should be a large terminal, not small. What most people do is run a heavy gauge wire from that terminal over to the "hot" terminal of the starter solenoid. That becomes a second high-current cable from the alternator to the electrical system.

[mini|inim]

Ok thanks. That helps a lot.

The thickness I was talking about is the diameter of the wire. The solid brown is around 3mm and the other 2 wires are about 1.5-2mm

Thanks for all the help. I will put it on and see what happens.

Cheers