Lucas DR3a Wiper Motor Self-park fix

[svenedin]

No special revelation or secret here but I have just found the issue with my non-functioning self-parking wipers. For 35 years I have had to manually park the wipers by switching them off at exactly the right time. It has always been a slight irritation!

With everything out of the engine bay I thought I would have a look at the wiper motor. It could do with new carbon brushes and a bit of a commutator clean up but is pretty good. I then got the multimeter out and measured the resistance between the top contact and the metal slider (just because it is a convenient point to measure) with the cap fitted. Open circuit. I realised that the copper self-parking contact was not contacting the lid properly. A bit of careful bending and the contact was making contact but the resistance high at 300 Ohms+. No good. I then realised that the brass contact area was very dirty and cleaned up the contact to bright brass. Measured resistance again, 0.2 Ohms. Job done! Note that the cut out area of the brass contact ring on the inside of the cap is non-conducting as this is the point at which the wipers should park with an open circuit.

Stephen


Copper self-parking contact was not contacting the domed lid at all. Carefully bending makes a good contact

IMG_1378.jpeg (3.54 MiB) Viewed 7547 times

Brass contact ring tarnished. High resistance. Needs cleaning to bright metal.

IMG_1379.jpeg (3 MiB) Viewed 7547 times

[geoberni]

Exactly the same issue as I had with Basil's Dip Switch (mentioned recently). Clean up the contact area and good as new.

[svenedin]

Incidentally, for future reference, if anybody wants to know what the correct gear wheel is for a late Minor, it is 150 degrees.

IMG_1381.jpeg (3.47 MiB) Viewed 7515 times

[svenedin]

I re-painted this wiper motor a few years ago. The black wrinkle finish that I used on the armature housing has been extremely durable but the clear acrylic lacquer that I used on the gearbox cover has not been a good solution. I think the gearbox cover and dome were originally plated, possibly nickel plated. Over time this plating layer fails and the steel underneath rusts. I thought that clear lacquer would work but it doesn't seem to have afforded much protection. I think I will have to paint the cover with actual paint now rather than lacquer. I think I'll use light silver like the underside of the cover.

Of course, even though I am working on this single-speed DR3a I am still pondering getting a 2 speed kit from ESM (using the W14). Last Minors on Tour in Holland was very wet and the single speed wipers were not up to it. It was quite scary.

Stephen

IMG_1384.jpeg (2.11 MiB) Viewed 7411 times

IMG_1383.jpeg (2.72 MiB) Viewed 7411 times

[svenedin]

New carbon brushes, new spring and new spring end holder things. The old spring looked OK but it was not until I fitted the new spring that I realised how weak the old one was. Now there is good tension on the brushes against the commutator. Top cap contact cleaned up.

IMG_1386.jpeg (2.57 MiB) Viewed 7379 times

IMG_1385.jpeg (1.2 MiB) Viewed 7379 times

[geoberni]

I re-painted this wiper motor a few years ago. The black wrinkle finish that I used on the armature housing has been extremely durable but the clear acrylic lacquer that I used on the gearbox cover has not been a good solution. I think the gearbox cover and dome were originally plated, possibly nickel plated. Over time this plating layer fails and the steel underneath rusts. I thought that clear lacquer would work but it doesn't seem to have afforded much protection. I think I will have to paint the cover with actual paint now rather than lacquer. I think I'll use light silver like the underside of the cover.

I faced the same decision a few months ago.
I brought an original DB10 relay, circa 1955, and it was badly pitted and painted.
I could only confirm the final digit of the year by reading the inside of the stamping.

I cleaned it up with a combination of scouring pad and Ultrasonic Bath, but decided that clear lacquer/varnish just wasn't going to work, as after only a few weeks left out on the bench in the garage I could see it was tarnishing under the lacquer.
So I sprayed it with primer and Silver Wheel spray paint.
.

20240927_110824.jpg (1010.23 KiB) Viewed 7299 times

20240928_151019.jpg (1.07 MiB) Viewed 7299 times

20241209_121201.jpg (1.58 MiB) Viewed 7299 times

20241210_115812.jpg (1.17 MiB) Viewed 7299 times

[svenedin]

I'm glad it's not just me. I know, like paint, that lacquer must be applied to a properly prepared, grease free surface. Despite this, parts that I have lacquered start to corrode quickly. It just doesn't seem to afford the same level of protection as paint.

It's a shame because the parts do look good now but they won't stay good if not protected.

Stephen

[svenedin]

The plating has gone on these parts and they will soon rust. Lacquer wasn't a good solution to stopping rust so it's (reluctantly) time for paint.

IMG_1391.jpeg (1.63 MiB) Viewed 5467 times

This is the Jenolite "Chrome" over etch primer. I really like Jenolite paints but we all have our favourites and I think it's what you get used to using that makes the difference.

IMG_1399.jpeg (1.14 MiB) Viewed 5480 times