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ex-NSW Police 1970 MK II Cooper S
VMCI #43

The deluxe number is missing a zero.

Well spotted. I'll send them a telegram asking for the bulletin to be corrected and re-issued.

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

Dont know where i got the 4029 from. I think it was in a body parts book. Anyway i will change my database to 4028. Thanks Doug

Below are a couple of sections from the engineering drawing for the 12AUW wiper motor. Implementation details for the Mark 1 Mini as per the technical bulletin (above) and parts catalogue (below) aren't included.

The relevant bits for this discussion are:

• AYA9188 released into production for the Mark 2 Mini series (YDO4, 5 & 6) on 10/1/1969 with 110 degree angle of wipe.
• Version with 105 degree angle of wipe introduced on 26/6/1970.
• Rack stroke reduced from 1.312 to 1.252 on 20/7/1970 (presumably by relocating the pin mentioned earlier).

You got it from the parts book below.

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

And that parts book has the deluxe wipers changing almost 9 months earlier than all the other models. Car 23860 would be around July 67.

The rest are correct except they have them changing 1 car later.

Winabbey,
You never cease to amaze me with all the Mini info you have accumulated.

It's interesting to see they changed the finish on the cover plate to identify -ve earth from +ve earth cars.
I hadn't given it any thought when I changed my car to -ve earth.

I had to brush up on my DC motor theory but here goes. (High Voltage power generation and transmission systems yes- DC motors not so good and it was a longgggggg time ago)

The Aus Preslite motors are permanent magnet motors. This means that if you connect +ve earth motor to a -ve earth car or reverse the battery connections, like I have done, the motor will run in the reverse direction and the cable drive wheel will rotate in the opposite direction.
The left hand rule for DC motors for force, field and current comes into play here. The magnetic field is acting in the same direction but the current is flowing in the opposite direction so the resulting force on the armature causes it to rotate in the opposite direction.
Does this matter?
As far as the wiper wheel box is concerned it doesn't care as the cable is still being pulled back and forth and drives the wiper spindle in the correct phasing to ensure the park function still works.
The motor armature is driving the cable wheel in the opposite direction so the end thrust on the armature will no longer act in the original direction.
Is this a a problem?
Don't know as I haven't pulled one of these apart to examine its innards.
My wipers are still working OK 30+ years after reversing the battery polarity.
Preslite, who made the motors, or maybe BMC?, thought it was necessary as they changed the colour treatment of the cover to distinguish the -ve earth motors from the earlier +ve earth motors.
So what is different?
In order to make the motor turn in the right direction they could either change the direction of the magnetic field in relation to the brushes or reverse the wiring connections to the brushes to ensure the current flow in the armature was in the same direction as the earlier +ve earth motors.

What did they actually do? Don't know unless I pull a sample of each motor type apart and examine the innards.
Probably just reversed the wiring as that would be the easiest thing to do.

Other Ausmini forum people will know.

A bit of trivia.
The so called DC generator actually generates AC which is then rectified/converted to DC by the commutator.
The commutator and brush gear are actually a mechanical rectifier. No solid state invertors, diode stacks or mercury arc rectifiers here.

A bit more trivia.
When my 68 S was new the wipers kept blowing fuses and it turned out to be the wrong wiper switch. The factory had installed the wrong wiper switch to the Aus motor and of course it didn't work with the permanent magnet motor with regenerative braking.

Hope this helps.

RonR

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68 build Mk1 Cooper S
72 Clubman GT project. Total restoration required