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bsa M20 oil pump drive shaft removal

A Q regarding replacement of the 1943 M20 oil pump drive shaft - apparently there is a
"keeper", a spindle retaining pin, that maintains the oil pump spindle in place. My spindle gear is worn and i am considering replacement, and i can't see where the retaining pin is accessed, either from the inside of the timing gear chest or the outside. The m20 manual does not specify, nor can i tell from the exploded assembly drawings. I have yet to see a blog that discusses this technical detail. The only other option is access from inside the crankcase. Can someone verify this, or set me straight?

Thanks in advance

Dave W

email (option): dwdiak4@gmail.com

Re: bsa M20 oil pump drive shaft removal

Dave, take the timing cover off and you will see an extra hole bottom left over the oil pump spindle. The oil spindle retainer is in this hole. There is usually a washer on top of it to remove first which is just there to take up any end float. The manual will tell you to use one of the case screws to screw into the retainer, but this is wrong as the thread inside the retainer is 1/4 X 26 BSCyc and the case screws are course Whitworth thread.

Simply screw a bolt into the retainer and pull it out. Ron


PS. Much as I hate Photobucket! Here is the page from the manual.

 photo scan-170504-0001_zpsmqabuaer.jpg

email (option): ronpier@talk21.com

Re: bsa M20 oil pump drive shaft removal

You will also need to remove the oil pump as the drive shaft is removed from the crank case by dropping it downwards...

Beware of (and avoid) the Indian replica drives which have incorrectly machined gear teeth...as sold by Draganfly and others..

My advice would be to buy a UK manufactured drive shaft from one of the reputable Gold Star dealers such as Phil Pearson...

Wear of the drive worm is usually the result of running with a tight oil pump...The pump should turn freely by hand when removed from the cases..

If that is not the case that must be rectified before fitting a new drive to avoid premature wear...Ian

email (option): ian@wright52.plus.com

Re: bsa M20 oil pump drive shaft removal

Ron, Ian

Thanks. The illustration in the manual is not clear to me but now I understand.

Dave W.

email (option): dwdiak4@gmail.com

Re: bsa M20 oil pump drive shaft removal

What's not clear Dave? The retainer slides in that cut away hole to the left of the indicated oil drilling with the washer I mentioned on top of it. Ron

email (option): ronpier@talk21.com

Re: bsa M20 oil pump drive shaft removal

Ron

Thanks for your input. The item has been extracted, inspected, cleaned and ready for
installation as soon as i receive a new spindle.

Dave W.

email (option): dwdiak4@gmail

Re: bsa M20 oil pump drive shaft removal

Guys,

Thank you for this questions bank as really useful!

Cheers

Danny

email (option): burt.danny@yahoo.co.uk

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