I've removed the 3 tie bolts and the nuts on the tie studs holding the magneto straps, I've also removed the timing gear bolts leaving a larger nut (the one at the bottom right of my pic) but as this seems to be retaining the crankshaft itself should I remove this too? A few light taps with a rubber mallet shows very slight separation of the crankcases so it seems I'm on the right track.

If I do have to remove the final nut I'm planning to use a bar through the small end on some blocks to keep the crankshaft secure - is this the best way of going about it?

Gary

email (option): gj.owen@hotmail.co.uk

Yes you will need to remove that nut, then the timing gear support plate and the cams. And the oil pump drive spindle. Then you will probably need a puller to remove the worm gear that drives the oil pump spindle. Ron

email (option): ronpier@talk21.com

email (option): gj.owen@hotmail.co.uk

I've never found a completely successful puller. But you need a two leg puller that has Fairly sharp claws to get behind the gear. I usually struggle a bit with a small cheap puller which I have ground the claws down on. Ron

email (option): ronpier@talk21.com

Hi Gary, I adapted this car ball joint splitter I had laying in a drawer. It does the job very well!!

Ian aka Frank

Hi Gary, I adapted this car ball joint splitter I had laying in a drawer. It does the job very well!!

email (option): gj.owen@hotmail.co.uk

Good one Gary!! You'll probably have to attack it with a grinder to make it fit plus the clearance between it and case not much.. Don't forget to place an old bolt into the end of the crank for splitter bolt to act against also..

Ian aka Frank

Good one Gary!! You'll probably have to attack it with a grinder to make it fit plus the clearance between it and case not much.. Don't forget to place an old bolt into the end of the crank for splitter bolt to act against also..

email (option): gj.owen@hotmail.co.uk

No Gary! In your top picture just in front of the oil pump spindle and part of the crank case casting you can see a tapped hole (not one of the timing cover screw holes). You must screw a bolt/screw into this (1/4" BSF I think) and pull out the spindle locating dowel. The spindle will just push out then. Ron

email (option): ronpier@talk21.com

email (option): gj.owen@hotmail.co.uk

The spindle location plunger has to come out first Gary (marked with red arrow).




Amended Ian..

BTW Ron, I'm not trying to steal your thunder.. It's just it takes me that long to upload pics to photobucket, you've replied before I've had chance to finish mine..

Note as well that the instruction to use a timing cover screw to pull out the drive shaft locating peg is incorrect when applied to a WDM20...

This is a throwback from pre war days and something BSA failed to amend in the manuals...

As Ron points out the thread in the peg is 1/4" Cycle thread...The thread of the timing cover screws are 1/4" Whitworth...

Pre war engines used the finer Cycle thread for the cover screws as well but this was subsequently altered.. My 1936 G14 for example, had the finer threads on the casing screws (not a great plan into aluminium)...

Also note the washer shown with the peg in the illustration from the manual..

This is fitted to some, but not all engines when the retaining peg is a little short and is sitting below the gasket face of the crank cases...

The washers are usually a snug fit in the cases and must be prised out using a scriber or similar before extracting the peg...The hole in the washer is too small for the 1/4" screw to pass through it..(and its OD is also smaller than a standard washer...

If missing (and needed) it can be made by filing down the OD of a 1/4" washer..Ian

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

Finally got round to removing the oil pump pinion using a modified ball joint splitter (thanks for the tip Ian) and crankcases separated easily.

Left hand casing came off crankshaft ok but the right hand (timing) side is a different story and it seems to be stuck fast. I've tried a few firm taps on the crankshaft but I'm reluctant to give it any more in case there's something else I should be doing like warming the crankcase with a rag soaked in boiling water maybe?

Any tips anyone please?

Gary.

email (option): gj.owen@hotmail.co.uk

Sometimes the crank sticks in the bearing if the engine has been stood for a long period....

First remove the crankshaft pinion...Next get a piece of bar and get someone with a lathe to drill a hole up one end that is just a clearance fit over the diameter the crank pinion sits on..

Drill deep enough so that the end of the bar sits against the shoulder on the shaft, not on the end of the shaft...

You will then be able to drift the crank out of the bearings without damaging the end...Ian

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

Ian Wright

Sometimes the crank sticks in the bearing if the engine has been stood for a long period....

First remove the crankshaft pinion...Next get a piece of bar and get someone with a lathe to drill a hole up one end that is just a clearance fit over the diameter the crank pinion sits on..

Drill deep enough so that the end of the bar sits against the shoulder on the shaft, not on the end of the shaft...

You will then be able to drift the crank out of the bearings without damaging the end...Ian

email (option): gj.owen@hotmail.co.uk