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Cooper S Generator
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Author:  phillb [ Mon Jul 17, 2017 5:09 pm ]
Post subject:  Cooper S Generator

Some may have seen my post where my generator failed me last weekend.

Having now pulled my old one down and looking at the one I was able to get as a replacement I have a couple of questions as I have noticed some differences.

If anyone has late 68 C40 Lucas on their Mini I would be interested to know if the D terminal (the larger one) is closer to the front or back of car when fitted and does it point up or down?

Also the Cooper S apparently had a larger pully. What size is it and what size is standard? Can anyone provide pics of a Cooper S fan and pully?

Cheers


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Author:  gtogreen1969 [ Mon Jul 17, 2017 5:39 pm ]
Post subject:  Re: Cooper S Generator

My large D terminal points down.

Image

It is a C40 22704A with a large pulley.

Image

The pulley is 4 inches across. No idea what size std is.

Image

Author:  gtogreen1969 [ Mon Jul 17, 2017 8:43 pm ]
Post subject:  Re: Cooper S Generator

I had a google and found the following part numbers and application and some sizes. These are UK pulleys.

12G1054 = 2.75"
12A34 = 2.95"
12G2102 = 3.6" or 4"
12A1772 = 3.1"

Attachment:
Dynamo Pulleys.jpg

Author:  phillb [ Mon Jul 17, 2017 9:04 pm ]
Post subject:  Re: Cooper S Generator

Ok ta. The dynamo I had on and the replacement are both 3 1/4 in from memory so I'm guessing that's standard. I had an older dynamo with a big pulley 3 5/8 that I thought might be closer to cooper S size.

Shame that document doesn't show dimensions and I wonder where the measurement is normally taken for a pulley??


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Author:  gtogreen1969 [ Mon Jul 17, 2017 9:11 pm ]
Post subject:  Re: Cooper S Generator

phillb wrote:
Ok ta. The dynamo I had on and the replacement are both 3 1/4 in from memory so I'm guessing that's standard. I had an older dynamo with a big pulley 3 5/8 that I thought might be closer to cooper S size.

Shame that document doesn't show dimensions and I wonder where the measurement is normally taken for a pulley??


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Here is a NOS 12G2102 with 3.6" measured across the outer diameter. http://www.ebay.com.au/itm/252459177695Image

It will be interesting see what others have. My car is just charging at idle. Maybe my 4" pulley is too large.

Author:  phillb [ Mon Jul 17, 2017 9:15 pm ]
Post subject:  Re: Cooper S Generator

And you say yours is 4in dia?


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Author:  gtogreen1969 [ Mon Jul 17, 2017 9:16 pm ]
Post subject:  Re: Cooper S Generator

phillb wrote:
And you say yours is 4in dia?


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Yes. I will recheck it again using my verniers.

Author:  phillb [ Mon Jul 17, 2017 9:19 pm ]
Post subject:  Re: Cooper S Generator

Maybe Australia went up a size or two compared to U.K.?


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Author:  gtogreen1969 [ Mon Jul 17, 2017 9:40 pm ]
Post subject:  Re: Cooper S Generator

Rechecked with the verniers. 3.88". My ruler had some parralex error issues. Still a long way off 3.6". SorryImageImage

Author:  minimans [ Tue Jul 18, 2017 3:44 am ]
Post subject:  Re: Cooper S Generator

Pulley size is set by RPM used if you rev the bollocks off it you need the larger pulley to keep the actual dynamo rev's down. A dynamo will come apart and destroy itself at high RPM hence the larger pulley to slow it down....................

Author:  drmini in aust [ Tue Jul 18, 2017 6:15 am ]
Post subject:  Re: Cooper S Generator

997 and 998 Cooper had the big pulley also.

Author:  phillb [ Tue Jul 18, 2017 7:44 am ]
Post subject:  Re: Cooper S Generator

gtogreen1969 wrote:
My large D terminal points down.

Image



Thanks. The one that was on the car was above the opposite brush and pointing up. Seems to be the odd one out looking at other cars now. Perhaps originally off a different model car. It was always a bit of a stretch for the wire so that explains why!


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Author:  winabbey [ Tue Jul 18, 2017 11:17 am ]
Post subject:  Re: Cooper S Generator

Phill,

The Lucas C40 dynamo for a Cooper and Cooper S should be part number 22742 (stamped on the body) according to the parts book and some OS forum discussion.

Attachment:
PUB1012 N06 R.jpg


The pulley for the Cooper and Cooper S is part number 1H998, superceded to 12G2102, and then AYH61 for the Australian equivalent.

For reference, the pulley for all other Mini models is part number 12A34 and AYG9029 for the Australian equivalent.

BMC Australia engineering drawings for both types shown below.

Attachment:
AYH0061 Pulley Generator Cooper and S 1H998 wm.jpg


Attachment:
AYG9029 Pulley Generator Mini 12A34 AYB0041 wm.jpg

Author:  gtogreen1969 [ Tue Jul 18, 2017 4:24 pm ]
Post subject:  Re: Cooper S Generator

Great info Doug. Looks like my car has a Cooper Dynamo 22704A. I think i might go down a pulley size so i can get better charging in traffic and at idle.

Author:  winabbey [ Tue Jul 18, 2017 4:28 pm ]
Post subject:  Re: Cooper S Generator

gtogreen1969 wrote:
Great info Doug. Looks like my car has a Cooper Dynamo 22704A. I think i might go down a pulley size so i can get better charging in traffic and at idle.

I think you've misread the parts book. Dynamo 22704 is the one for all Minis except Cooper and Cooper S, which are 22742. :wink:

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