For my M20 gearbox I am missing part nrs 154224 ( gear index plunger) and 154225 ( gear index plunger spring .
- what does the gear index plunger do ?
-is it essential ?

If it is: by the looks if it, it is essentially a hollow tube with a pointy end. Can anyone give me the dimensions so I can have one machined up ?
And can anyone tell me the thickness of the wire of the spring and it's length so I can see if I can find something suitable ?

Many thanks in advance ,greetings from sunny Phuket

Maxim Jurgens

email (option): siamsailing@gmail.com

Hi Maxim,
The plunger and spring form part of the positive stop mechanisim that centres the gear lever, they are solid made from 6mm or 1/4'(can't remember) rod about 1/2" long with a 90 degree point. I have made these from tool steel or old clutch push rods, hardened and tempered.
Not sure on the wire gauge of the spring but they are quite stiff.

Hi Maxim...As Matt says the indexing plate plunger is solid. The larger plunger inside the main body of the gearbox is hollow....

Here are the dimensions...

Plunger..Outside diameter: .215"-.217"..Length: .620"-.625"

The plunger has a point with a slight radius at the tip machined onto one end to engage the 'dimple' in the indexing plate..

Spring: Outside diameter: 3/16"(.187") Length: 1/2"(.500")

Material: No.22 Imperial wire gauge (Outside diameter of wire .028")

7 complete coils....Ian

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

Is this the part you are looking for? It looks similar to what I have, from memory.

http://www.ebay.com/itm/BSA-WM20-M20-M21-B31-B33-parts-job-lot-/151524944631?hash=item2347972af7:g:evYAAOSwkNZUmHKB&vxp=mtr

Best wishes, Allan Hunter

email (option): allanmatchless@yahoo.com