Plunger gear change not returning.

[buggychief]

Hello, when changing gear my gear change lever often does not return back to the central position so i have to give it a nudge and only then it springs back. i have fitted new return springs and have checked that the gear change pawl is free which it is. i will try and fit a thicker gasket between the inner casing to give more clearance as i believe the pawl might be fouling the cam plate. any other ideas please??

[bikerjohndavies]

Hi, I also have a similar problem but only when changing down from third to second, the lever stays up and I have to give it a little nudge to drop back down. On all other changes it returns to the correct place. It has become automatic for me to give it a nudge now bit would be good to work out what is causing it. I also changed springs and checked that everything seems free. Cheers, John

[muskrat]

G'day buggychief,  .
Has this started since the box has been worked on (tampered with)? Or did it just start misbehaving by it's self?
I find with mine anything but the thinnest of gaskets will make selection difficult or non existent.
The pawl is spring loaded.
Cheers

[buggychief]

this is the first time i have used the gearbox, the original broke off the top mounting lug over 20 years ago and was stolen from my garage with most of the other parts of the bike, i have since purchased a 1956 Royal Enfield Bullet minus an engine and fitted my 1957 plunger A10 and what was a spare gearbox, so i have build a "Benfield" so now i am using the engine and gearbox again, so this is a new problem. i have taken the inner and outer cases off and checked the pawl which looks to have some rubbing marks on it. i reassembled the casing with new gaskets and it is worse than before, giving me the idea that a thicker (or 2) gaskets will bring the pawl off the selector which i believe didnt have enough clearance. 

[muskrat]

Is the pawl returning to center (via the ball & spring)? Try it with no gasket between the case and inner cover.
You'll be an expert at getting it apart in no time . Just noticed where you are and hope you've got AC in the shed  .
Cheers

[duTch]

 Also have a read of   Orabandas' post from yesterday.....
http://www.a7a10.net/forum/index.php?topic=8810.0;topicseen

Is amazing how something seemingly so insignificant can be otherwise....!
The beauty of Thea boxes is they are so easy... 

[buggychief]

the pawl is returning to the centre, will try without a gasket over the weekend and see what happens, it does look like the pawl is rubbing on the camplate thats why i considered using a thicker gasket, supoose i can try both options and hopefully cure the problem as it becoming a pain having to keep flicking the gearchange back when changing gear, the weather here isnt too bad now only 37C during the day if it gets too hot i bring the bike into the house.

[buggychief]

So far, i have removed all the inner cover gaskets and used silicone sealant as a gasket which has the best result.
The problem of the gear change not returning to the center after changing from 4th to 3rd seems to get worse when the bike gets hot. i added 2 gaskets previously and it made it worse, causing the gear change not to return in all the gears.
The bike has new gear change return springs which are strong and the pawl rocks freely when removed.
any suggestions please.

[muskrat]

G'day buggycheif.
The only things left are, 1: the selector arm pivoting easily, 2: gear selector arm that engages between the springs is rubbing on the cover or 3: the spindle bushes are worn causing 1 & 2. If all that is good we're back in to the camplate and bearing. Have you tried the camplate plunger in different positions (backed off or tightened up)?
Cheers

[buggychief]

Hi Muskrat, i did wonder if the bushes when slightly worn would cause the shaft to skew and jam, will give it a good look.

i havent tried backing off the cam plate plunger yet, it is set with the 2 threads showing and changes gear really well it the fact i have to keep nudging the gear change back when changing up the gearbox which has at times been dangerous in a emergency situation. the driving here is unbelievable with little or no respect given to bikes.   

[muskrat]

We'll get to the bottom of it eventually. You say it's mainly going from 4th to 3rd and worse when it's hot, but the gears go in well. Usually if there's a prob with 3&4 or 1&2 it points to a selector fork but as noted the gears engage well  . A problem getting worse when hot points to bushings. Does it happen at all going from 2nd to 1st? If it did its the upward travel of the lever. I'd even try moving the lever a spline or two in either direction to see if the problem differs.
Cheers

[bsa-bill]

scuse me chaps as I know nowt about plungers, do they index similar to swinging arm? if so might need moved a bit from dot perfect (selector fork hits case and upsets/jams spring lever combo)

OK I'll crawl back into my S?A comfort zone)

[muskrat]

G'day Bill.
No they are different in a few ways. As far as indexing they can't be wrong.
Cheers

[bsa-bill]

Aha - so there you go, I've learnt something today

[buggychief]

yes it also happens between 2nd and 3rd but not as much, i have a spare gear change shaft might try that and see if that makes any difference.