Morris Minor Owners Club

Hi Folks
I was thinking of replacing my dynamo with an alternator as most of my driving around town is at low revs, and the ammeter usually shows discharge for a lot of the time.

Am I right in thinking that the dynamo will not be outputting any charge at or just above tickover?

Also, if I do fit an alternator (I have several Lucas LRA100's for the boat) do I have to change the crankshaft pulley for a solid one? I have heard that they can break out with the extra load?

Thanks in advance
Dave

Yes, if you do lots of low-rev'y driving around town particularly in winter the dynamo will struggle. It may well be worth (if you like dynamos, I'm not mad keen but they are vastly more reliable) giving the dynamo a service to make sure you're getting the very best out of it.

However, if you do convert to an alternator (even a Lucas LRA100 *shudder*), no you don't need to change the crankshaft pulley...

[I hate the lucas LRA100; I got through 4 of them in 50k miles, they'd just *die*. I've got something else on there now, can't remember what though I'm afraid, I posted on here at the time...and it's much of a betterness]

put an altinator on it i have and have had no problems at all.

If you do fit an alternator, get the Ford Sierra Flat Back, much more reliable than any Lucas Alternator. Remember Lucas = Lord Of Darkness

Lucas have been fine for me! The older 16/17/18 ACR units are self contained and often only £1 or so at auto jumbles. Just check you get one which is 'handed' correctly for the Minor - and make sure the pulley lines up perfectly with the other two on the engine. Usually needs a washer between the alt and the water pump - and of course you need a new longer bracket for the rear mounting of the alternator - because it is shorter than the dynamo. Most alts are also -ve earth, so if you haven't already converted you will need to do that when you fit the alt.

Thanks folks
Yes I'm already neg earth. I think I have an old BMC alternator in the shed somewhere, I'll dig it out and give it a go. If not I'll pop down to the scrappy and see if I can get an old Mini one (along with a heater unit ). Am I right in thinking that direction of rotation is not important?
Oh yes you're right Kate, the LRA100 does have a habit of just dying, I have had several in the boat, but they're cheap

Update:
Fitted the LUCAS 'BMC' one yesterday, works a treat. I can use the wipers, fan and headlights ath the same time.
Thanks for the help
Dave

I bought an alternator kit from well known MM parts supplier last Sept and after a few of weeks the battery got fried (distorted casing and hissing noise from the battery after a run). Gone back to dynamo as thankfully I hadn't tidied the wirirng by removing unused wires. How can I check whether the alternator has a fault or could it have been the battery at fault?

Local motor factors should be able to test the alternator output, which should be about 14.5 volts on the test machine they use. Distorted battery case and hissing is a sure sign of over charging, you were lucky the battery didn't explode. Be sure to replace the battery if you haven't done so already.

Did you rewire the car to take the alternator? If you left the wiring per dynamo wiring, the alternator would be charging through the regulator control box, which could cause the problem. When the regulator opens and the alternator runs into no load, the voltage will climb to over 400 Volts! wrecking the alternator in an instant.

If anyone wants a little more power out of a dynamo yet doesn't want to change to an alternator then there is an alternative.
I found out years ago, when I had a Hillman Imp, and bought a Singer Chamois for spares, that there was a slighlty higher output dynamo available - normally found on cars with twin headlights. I THINK it was fitted to what is called "Police spec" vehicles.
The way to identify is look at the body - standard has a reduced / stepped dia towards rear (where coil bracket is attached) whereas the higher output is the same dia.
Not a massive increase and personally I fit alternators but worth noting if you want a little extra power yet original looks.

Paul Humphries.