Here's a reminder not to forget to check your M20s gearbox oil level every 500 miles max...particularly if you don't have a sealed bearing fitted.
Recent testing of an air cooled gearbox was not entirely successful... ....Ian

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

Does this mean I can get rid of my radiator?

email (option): britool51@hotmail.com

There must be a lot of gearboxes destroyed this way. Wonder how they kept the oil in in the old days when there were no sealed bearings.

Could it be that these boxes were originally designed upright with the layshaft vertically under the mainshaft (1927 sloper), than the oil level for the layshaft bushes is less critical?

Regards, Michiel

My own WM gearbox leaks so copiously that I have taken to pumping it full of general purpose grease along with a bit of gear oil.

I am thinking that I should install a grease fitting on the gearbox filler cap to simplify matters, but have decided to pull the box down instead to install a modern sealed bearing.

Chain oiling has not been a problem: I hate to lose that feature

JDE

email (option): teladelujo@msn.com

though i dont do heavy mileage last year i checked my g/box and it used nothing/very minimal amount when i put it on the rear stand i put a small block of wood under it on the primary chain case side it then doesnt leak oil if you put it on the field stand you loose the whole g/box contents in a couple of hours and ian go and stand in the corner

..It's not my gearbox Roger!..Just one I have in for a rebuild...Ian

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

I use liquid grease in mine,put it in with a small pump,if I knew about this problem when rebuilding would have used a sealed bearing.To lazy to change now as the grease seem`s to work fine.I just pump in the grease until it starts coming out of the filler hole,but I don`t do racing gear changers just nice slow ones. Jeff

sorry ian you can be the milk monitor for the rest of the week

What is a good sealed bearing part number? Are there any other mods required to seal the gearbox or other prudent mods as long as you're in there?

Will be doing up my gearbox soon.

Thanks!
Kevin

Hi Kevin..6207 2RS...It's a metric bearing, 2RS indicating two rubber seals. I remove the inner seal to allow gearbox oil in on the advice of a friend who was the chief developement engineer at RHP bearings, but not everyone does...No other mods are really necessary..Ian

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

So very appreciated, Ian. Just ordered one from Amazon for $6! Thanks.

Kevin

And for some additional tips see the Technical Section, http://www.wdbsa.nl/download/Gearbox%20work.pdf

email (option): viaconsu # planet dot nl

Hi Kevin...Before you assemble the M series box it is best to shim each shaft individually in the main case to ensure correct end float.(including the gear selector shaft) I shim them to give .005"-.010" end float.Don't forget to fit a dry inner cover gasket when setting the end float. Note that on final assembly, when you put on the nut that compresses the kickstart ratchet pinion spring this should only be hand tight and held in position by the locknut. Check after tightening the locknut that you still have end float on the mainshaft.
Correct clearance for the sleeve gear (top) gear bushes is .0015"-.0035". For 3rd gear on the mainshaft and 1st and 2nd gear on the layshaft correct clearance is .0025"-.004". I usually go for the lower figure.
Correct clearance for the layshaft inner cover and main case bushes is .0015"-.0035"...Ian

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

Ian, Hans... thanks so much guys. You guys and this site are invaluable. Can't wait to get the M20 running so I can post a video like the one posted yesterday!