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MG MGB Technical - Request for help.. UK alternator replacement

Hello all,

I've just had a lucas alternator go full short.. The resulting high current flow has melted some of the engine bay wiring.. well, they don't call me 'lucky Bob' for nothing!

Anyway, has anybody any info on any 'drop in' UK replacements?? I've no preference for make or connection type etc.

Any help would be appreciated.

Bob K.
R Kenchington

Bob , Go to www.onefastmgb.com. I had the same problem as you and this site helped me solve my alternator problem.

Good Luck, Davy
Davy Crocker

I use a Bosch 70amp altenator in both my Sprite and 80 MGB. These have a pulley that perfectly lines up with the pulley system. The pulley on it has a bell shape to it. I had to make a spacer of about an inch to fit inside the mounts and a long hardened bolt instead of two bolts. The adjusting bracket will bolt up to it with little modding and in the case of the plug on the back of the altenator, on my 80 B the original plug fits with no mods at all. No more Lucas "pulsing" at idle with that 70 amps either.
Mwhitt

I assume you don't want to just fit a new one from an mg specialist (MGOC, Moss, MGBHive etc etc). Unless you have extra elctrical bits it should be perfectly adequite. How long did your last unit last? The alternator from some Ford cars can be fitted with very little alteration. I think from a Fiesta, but not sure which era. The archive will probably contain the answer if you can find it!

Iain
I D Cameron

Hello again,

Thanks for the replies..

I've no idea how old the existing alternator is, it's not original as shown by the rounded mounting bolts.
It would appear that the wiring damage extends right back to the battery (melted insulation, some now carbonised). I'm just glad that a battery cut off switch was fitted. The smoke was quite unbelievable!

I'm going to look for a bosch unit for now.

Again, thanks.

Bob K.
R Kenchington

I'm with Iain. Unless you had running problems (apart from its final demise) the easiest option is to fit a pukka Lucas replacement. Otherwise you are going to be dealing with mounting and connection issues. Lucas gets an unfairly bad reputation, simply because they were the original suppliers and the bits are now 30 to 40 years old! A good Lucas replacement will be just as effective as anything else, and anything else is just as likely to suffer an early failure as Lucas.

If the battery cable has suffered it must have been chucking out smoke for some time before you operated the cut-off switch, and the battery cable, browns from the solenoid up to the alternator, and cut-off switch should be replaced. And if it really was some time before you operated the switch the browns will have damaged adjacent wires in the main harness, so you are possibly looking at having to replace this as well. If the fault occured when the car was unattended then that really was bad luck, and you should consider fitting fusible links in the brown wires coming up from the solenoid.
Paul Hunt 2

Hello,

Actually, I'm in the process of building a custom loom for the car. I want to keep the look of the '73 dash with the original switchgear but I want to 'engineer out' the potential problems from the original wiring design and ageing components.

The current loom is about 6 yrs old (from by a major supplier to the DPO) and had not been butchered too badly. However, the closer I look at the wiring diagrams the more I see that I don't like.

The car is mainly stripped for bodywork restoration and only gets started every couple of weeks or so. It took at most 60 seconds or so from turning the battery isolator switch on to near catastrophe.

I have no problem with using Lucas components whatsoever.. I do realise that '70s equipment was built to a price and has done very well indeed to be working at all after 30 - 40 years.

I intend to look for a bosch alternator from Ebay for now.

Regards,

Bob K.
R Kenchington

You might want to have a look at the Bosch 0120 489 346/7 form the Escort XR3i. That's the one I used.
N.C. Nielsen

Thanks for the Bosch part number.. Does anyone know if this alternator was fitted to any other UK cars??.
I asked about this in my local motor factors.. The guy told me that **everyone** just identifies an alternator by the car make/model/year and that the Bosch part number is not a great deal of use on its own.

ho hum.

Bob.
R Kenchington

Bob
I had a couple of XR3i's back in the 80s before they became naff, their alternators aren't any more reliable than Uncle Joe's [bought the T shirt etc], there is nothing wrong with the Lucas ones, they are cheap from motor factors and fit straight in and most of the 17/18 ACRs are interchangeable, even if the mounting is the wrong hand, just undo the through bolts and turn the casing round.
Ron
R. Algie

Bob,

Any Lucas 127 series alternator will suit your requirement. They were used on many Rovers and Fords until quite recently and are usually available with greater outputs than originally used on MGBs. All are readily available at breakers yards for about £10.

Don't worry if the one you get has a serpentine belt drive in stead of the MG V-belt. You can change the pulley over with the one from your dead alternator.

Regards

Peter
P L Hills

Thanks to everyone for their help and advice.

I've found a recon Lucas 18ACR on Ebay for a very good price. I'll still keep looking for higher output alternatives.

Bob.
R Kenchington

Bob,

If you are not too far into building your custom loom you may want to consider the loom that Dan Masters supplies. It has lots of relays and fuses in a central power block. Haven't actually seen one in real life, but looks like a great solution to me for a total re wire.

http://www.advanceautowire.com/

Iain
I D Cameron

Hello,

Yes, Ive seen this one.. It looks good but is very expensive for what it does.
I want a little bit more from mine.

Bob.
R Kenchington

Bob,

I'd recommend Dan Masters kit. I've just spent most of the winter slowly and at my leisure putting one of Dan's kits into my car. It wasn't perfect but is very well enmgineered, perhaps even over engineered. I modified my installation to include various upgrades but not all the ones you need.

Regarding costs, I felt it was competitive with buying a new (old design) loom from one of the UK suppliers - which was just what I didn't want to do.

If you have any queries, please contact me off line and I'll try to answer them.

Regards

Peter
P L Hills

I dropped in an old Mazda alternator made by Mitsubishi. It fitted very easily. I'm sorry I can't tell you the model number. As for wiring, I made my own harness, and the alternator was amenable to using spade connectors.

It's very handy if you can access a pick-your-own-part junkyard, as then you can take your time measuring before you buy.
Daryl

This thread was discussed between 23/03/2006 and 30/03/2006

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