Whereas the cam spindles and bushes receive positive direct lubrication, the intermediate gear bush and spindle do not...The spindle is drilled through and oil mist is forced into it's inner end by crankcase pressure as the piston travels through the downward stroke. The mist/oil then passes through a drilling in the spindle to the plain bush in the gear...The spindle itself has a double scroll machined into it and the intersection of the two scrolls occurs at the oil drilling...

The spindle can be fitted to the crank case with the hole in any position, being completely circular...The question therefore is what position should the hole be in?, or does it matter?...I have always fitted the spindle with the hole in the '6 o'clock' position, working on the theory that any residual oil inside the spindle will 'pool' in the bottom of the spindle and in the oil hole when the engine stops running, providing some lubrication on start up.....

I'd be interested to hear any opinions on this...As a matter of interest, if the bush needs replacing the readily available B31/33 small end bush can be used...It's dimensionally the same apart from being a little longer, but is easily shortened after fitting...Ian

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

Out of interest, the WM20 parts list shows the mag pinion idler spindle to have a central groove? #75. Ron

email (option): ronpier@talk21.com

DOH!..Correct Ron...I got the spindles mixed up:blush: ...The groove isn't quite as deep as the illustration shows and a single groove crosses it to assist in allowing the oil to move...However, the question is still the same one...Ian

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

When back from a vintage bike rally here in the west of Ireland - which by the way is perfect for our old ear horses - I can check my nos cases ian
These have spindles fitted from factory
Be Monday now
Br
Job

email (option): jonnyob1@googlemail.com

War horses I meant
😃

email (option): jonnyob1@googlemail.com

I was also going to suggest asking around to see if there is a pattern or fitted at random......(Since nothing appears to be written down about it). Otherwise I can't see anything wrong with Ian's theory of hole at the bottom.

It's possible that if you fit the hole at the top, it might need replacing again in 80 years. :relaxed: Ron

email (option): ronpier@talk21.com

'It's possible that if you fit the hole at the top, it might need replacing again in 80 years..'

Most engines have a worn bush/spindle...I've seen plenty of them...In practice I think the majority rarely replace either the spindle or the bush unless it's extremely slack....Likewise with gearbox bushes, it's easier to leave them if they aren't too bad...This is probably the cause of quite a bit of tooth wear...I suspect valve springs, fork springs, anti drain valve springs and most other bushes are regarded in the same way...You only have to look at the angle of the fork links on many M20s to know the main fork spring is no longer within tolerance...
Where possible I like to get everything back within tolerance when doing a full rebuild (as REME did) and it seems sensible to fit the parts correctly if there is a correct way...Ian

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

Hi Ian’
Got a scrap M20 engine here with STD bore so maybe never been apart (Absolutely seized solid)
The intermediate gear bush oil hole is between the 4 to 5 o’clock position,
Also have a spare set of cases and it is in the same place’ i’ll Mail you a picture hope it helps,
Regards, Tom.

email (option): rustytomm20@hotmail.com