Morris Minor Owners Club

The clap-hands wipers self park too! Earth is earth - so doesn't matter where the earth wire goes. The motor needs a direct live-all-the time (when Ign ON) feed - this is the green wire. It earths out through the rotory switch on the lid - ie - it runs round until that switch opens on the 'dead' section - the wipers are now parked. To make the wipers GO - the motor is earthed through the dash switch (green/black wire) - it starts to move, runs off the 'dead' section - and continues for a full rev. If the dash switch continues to be earthed - it will do another rev - and so on. Simples!

You explain it so well.

You've made it perfectly clear, between the two of you. Thank you very much, I'll post progress when the brushes arrive!

Brushes arrived yesterday, I fitted them, packed the gearbox with grease, put it together and fitted it. It worked! Once.

I could hear the motor turning, but the spindles weren't moving. I checked the cable drive, which moved freely and moved the spindles. I checked the wiper motor, but it stopped working again. I tried wiring it directly to the battery, and nothing happened.

I took it back out and apart, this time, cleaning out all the new grease, and using fresh engine oil instead. I left the gearbox cover off and wired it to the battery, and hoorah! It works again! I can see it moving around, not too fast (maybe 1 revolution a second?) but it's moving. I disconnect the wire to the battery, then re-connect to make sure it's not a fluke. It was a fluke. Now the motor just makes a slight noise (almost a gentle rumbling) but there is no motion apparent on the gear. I get the feeling something must be dislodging as soon as it runs once. Any ideas what these symptoms suggest?

Grease on the commutator? It's hardly worth struggling too long with this - just pick up another one !

I'm going to try it one more time, then give in and get another one. So, grease on the commutator is a no no? I don't know how these things work, could you explain a) what the commutator is, and b) why it shouldn't have grease?

Thanks!

The commutator is what the brushes transfer the electrickery too.
The presence of grease may well stop this happening which leads to the motor not working.
It need to be clean so they can make good contact.

I see, thanks. What about the bigger part on the same spindle (sorry for this vague description..). There is a similar looking part, but larger, a little further down, which spins in a moon crecent shaped part which is attached to the windings. If you're still with me..can that part be covered in grease/oil? It almost (or might) touches the casing, which to me suggests it's an earthing point. It also almost (or does) touches the crescent shaped part. I can't really tell, because the "spindle" located in the cover, so I can't see how it actually sits when it's all together.

I hope that made sense.

Not sure what to call this bit, the windings?
The bit that should be clean is the smaller part near the end that is made up of copper stripes next to each other around the shaft.
Have a look for how an electric motor works on line for a more complete description.

I got it the first time, I don't think my question was too clear. Either way. I cleaned it up, and it worked a treat. I disconnected, re-connected, and it worked. Did this a few times. Kept working. Went to install it, stopped working. I took it apart 2 or 3 more times afterwards, and then put it back together. Sometimes it would work, sometimes it wouldn't. I did have a look at "how electric motors work". I see the brushes change the polarity...which got me thinking. I noticed if I centred the brushes ON a copper stripe it worked. Now, if the copper stripes change the polarity, what happens when the brushes are in contact with two stripes? It's more likely than them being on just a single stripe..which *could* be the reason it only works when I centred them, and then any further attempts would have been down to luck as to where the motor stops spinning.

This is all theoretical, am I on the right track? All this aside, I've pretty much given up on this motor. I need my wipers for the MOT, and that's what's keeping this Minor off of the road, I've wasted a week doing this. Time for a wanted ad.

Blimey "change the polarity" is rather technical.
The way the brushes contact the commutator is built in, you can't, and don't want to change it.
If it works off the car, but not on, look at issues with how it is earthing and where the self park is adjusted to if you count this as central to them working.
Don't bottle out now, the feeling of satisfaction is x10 if you fixed it versus i just bought a new one.

The 'stripes' are the ends of windings - they are sequential round the Com - it doesn't matter if it sits on several at the same time - it should kick start and rotate. The brushes certainly don't 'change any polarity' - they do keep current flowing around the various windings in the same direction - so the motor will rotate according to Mr Fleming's Left Hand Rule! Simples !!
I suggest there may be some burned out windings in that motor - can happen if it sits 'stalled' with current running through a non-moving winding for any length of time. You could tediously 'ring them out' with a meter - but another second-hand motor will not be expensive!

Here's one will almost certainly do - it's closing in 50 minutes!
http://cgi.ebay.co.uk/LUCAS-DR3A-WIPER- ... 23034508d8
And all of £1:20 at present!
Just noticed he says non-working - but with your new-found skills .........

This 'new' one looks promising! http://cgi.ebay.co.uk/GENUINE-BOXED-LUC ... 33567b02e3

I just missed the first one, will watch the second one. Will keep trying to fiddle around with this one, I don't have much hope for it though

Dennis has answered your request in 'Wanted'!

Thanks, I've replied!