Alternator Alternative

finfont

Member
I've read in another P6 forum that some 3500 owners are replacing the 11AC alternator with a Lucas A 127, which is more readily available. In addition to ease of access, this alternator is purported to produce greater voltage (14 plus volts) and smoother performance. My recently rebuilt 11AC produces 13.3 volts at best. As the Lucas A 127 has an internal generator, when installing, I assume one would bypass the wiring to the external generator/regulator and simply have positive and negative leads on the alternator, but, I am out of my league here. The A 127 (LH) is said to fit into the mounting brackets without need for adjustment or alteration. One comment was to the effect that a higher gauge positive lead would be needed. Does anyone here have any further information or experience regarding this swap out?
 
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I am no auto electrician, but I believe the fact that your 11AC is putting out 13.3 volts is because it is being regulated by the regulator. I believe it is capable of more. Granted if you fit an A 127 you may see more volts at the battery, but that will be because the regulator has been changed as well.

So, being a 11AC owner as well. I would ask, is there a way to adjust the existing regulator like you used to be able to do on the old big black Lucas units ?
 
Thank you for the info. I was under the impression that the aging alternators were not capable of producing the recommended output any longer. Much appreciated! Drew
 
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ISOLATE THE BATTERY
1. Isolate the alternator relay control circuit at the 6RA relay:
Disconnect and make safe the brown wire to C1 from +12V permanent
Disconnect and make safe the white wire to W1 from +12V ignition
2. Disconnect the field control from the 11AC
Disconnect the brown/purple field + control wire
Disconnect the brown/green - control wire
3. Physically replace the 11AC with the A127.
Disconnect the brown +12V battery wire
Disconnect the brown/yellow indicator light wire.
SWAP THE ALTERNATOR
Reconnect the +12V connection
Reconnect the brown/yellow wire that was to AL to the IND terminal
4. Bridge the 3AW Ignition Light relay.
Connect the yellow wire to the brown/yellow wire (inline spade connector should do it).
RECONNECT THE BATTERY

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I believe that Lead acid batteries can tolerate charging at 13.8-14.1v long term. I see 14.7v on startup on modern cars, tapering down to 14.1v as the battery comes up to fully charged. What would be involved in updating from an 18ACR to an A127 ?

thanks
 
im not sure you would need to change the cable unless you where adding more electrical items or items that where going to draw higher amps?
 
Hi, this was my post of Facebook originally. If you use a higher output alternator you will need thicker cables as it will pull up a flat battery at the given output.
 
The 18ACR has two spades for output AFAIK, while the A127 has the same, with an additional stud for B+ doesnt it ?
I had a S2 Disco in Saudi (3.9, R380) , which came std with a 90A alternator, and the main system fuse was 100A (IIRC?). This model got a free upgrade there to a 120A alternator, a wire mesh grill, and the installation involved bypassing that main fuse.....
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Upgraded from this...
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I believe the A127 is just a modern, improved and standardized version of the ACR type alternator replacing all variants of it I think the double spade is because the specified limits for those connectors is exceeded but that also gives us a convenient upgrade path by simply doubling up the original cable.

With the P6, the battery cable is itself much heavier, so you only need to get it as far as the connector block. On cars with ammeters, the ammeter shunt (which replaces the block) gives you +/- 80 amps so it should be OK to run it through that still. The starter itself through the starter relay is on the battery side of the circuit.
 
Anyone know where I can get the HUGE 1/2 Lucas spades on this cable? (It's from a later 18ACR car wiring loom).IMG_20201013_005940.jpg
 
9.5mm (3/8"?) is the biggest spade I have seen or heard of. My light switch input is a 9.5mm .
 
Holden's might have them I think...Industrial electrical wholesalers carry them in various sizes, steer clear of the ones that specialise in Domestic housing wiring - they tend not to. Not sure who that would be over your way but I recall seeing some English companies on the net. I spent ages a few years back trying to buy the soft plastic covers in decent quantities.
 
Wow, good find! Actually the point of crimping is to work optimally with thin multistrand wire. It you solder the type of cable we have in cars it becomes stiff and brittle. Over time that can lead to failure through constant vibration. A properly crimped joint should perform as well as a soldered one.
 
Wow, good find! Actually the point of crimping is to work optimally with thin multistrand wire. It you solder the type of cable we have in cars it becomes stiff and brittle. Over time that can lead to failure through constant vibration. A properly crimped joint should perform as well as a soldered one.

If you look at the that terminal it only has one set of tags, whereas normally they have two, one set for the wire and one set to support the insulation.
I would crimp that one around the insulation, and solder the wire into the well available.
Of course you can fix it however you see fit.
 
Normally all these terminals were simply crimped on, but after all those years the copper of the wire corrodes and the contact with the terminal is not what it should be. So i also prefer to crimp and then solder all the new terminals.
 
Got one of those Jason (actually 3 of them).

Looking at the 1/2" spade connector in the original loom, I've never seen a wire attached like it. Indeed, the crimp is to mechanically hold the wire by the insulation. However, the wire itself is not soldered. It's heled on in by a copper strap which is soldered on the back. All very strange but in makes sense as the wire is not mechanically attached by solder it's effectively crimped by the bar.
 
I think the actual strands are spot welded to the connector ,which leaves like a bar where the copper is welded ( melted )
 
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