Gearbox woes

[a101960]

I am still trying to set up my gear box with I should add very little success. Before I do anything else I thought that it might be a good idea to consult the forum. So far I have had it apart 4 times and it still does not index correctly. I am able to select all 4 gears when the bike is stationary (this is with the dots dead in line) I have tried going up one tooth and down one tooth on the quadrant to see if it would improve matters, but it does not. One thing that I have noticed however is that the pedal does not always return to the middle position after selecting a gear. When I checked the return spring it seemed OK but I have ordered a new one to fit and see if this improves matters. Out on the road when I try it out I can select 1st, 2nd, and 3rd  if I manage to get into 4th then it does not want to change back down to 3rd, but with a bit of fiddling about with the gear change pedal (hooking it up and down) it will sometimes select 3rd on changing down. By fitting a new gear return spring am I clutching at straws? I know from what I have read that normally moving the quadrant tooth engagement position often cures the problem that I am having, but in my case this only seems to make matters worse. When I try to select gears with the bike stationary if I rock the rear wheel back and fourth as I move the pedal all 4 gears will engage. I am now totally puzzled about what to do next. Has anyone got any ideas?

[Greybeard]

This sounds a lot like the issue I had with my Plunger box a while ago. Removing the inner gasket cured it!

[JulianS]

Check for wear on the selector claw and quadrant.

Check the gearchange spindle for float. If it moves too far it is possible that the claw does not properly engage with the quadrant. You may need to move the outer bust inwards to rectify.

These boxes were designed to be assembled with very thin paper gaskets between covers and case. A modern thick gasket may allow too much movement.

[a101960]

Check for wear on the selector claw and quadrant.

Julian, thanks for your suggestion but both of these items were replaced. New quadrant and claw. The old claw was definately worn, I am not so sure about the quadrant though but I replaced it anyway. I had another play with it this morning and on selecting 3rd, I noticed that the pedal does not return to the centre position it stays stuck in the raised position (Pedal reversed to suit rear sets). On the plus side when parked up on the side stand the box no longer leaks oil. I fitted a new oil seal and one of SRMs oil seal sprocket nuts. Greybeard, I will investigate the gasket issue, however the replacement gaskets are identical to the original gaskets.

[coater87]

 We talked about the trouble I had putting mine back together.

 At one time I thought I had all 4 gears, but I seemed to be getting 3rd gear twice. It was like the claw would move the selector off the detent, at the same time I ran out of claw, and third gear would pop back into its detent. It sounded like I had 4 gears from the Clunks.

 At this point I would abandon the dots, and use fourth gear as the starting point instead of neutral.

 Lee

 

[chaterlea25]

Hi,
Something or other is causing the gearchange shaft to hang up and not return to the centre position
It has to go back to centre so it can be ready to select the next gear
If the return spring is strained or not fitted correctly then you will have trouble
The legs of the spring should be parallel to each other and sit either side of the shaft flat piece
when fitted the spring legs should sit nicely either side  of the alloy block on the outer cover

Earlier you said that you fitted a new quadrant arm, so you had to remove the gear change inner bush?
Did it go back in properly ?
If you loosen the outer cover a little does the gear change return to centre?
Swing arm gearboxes are not sensitive to gasket thickness (usually)

John

[bsa-bill]

Swing arm gearboxes are not sensitive to gasket thickness (usually)

Solved this on my bike by using  two gaskets on the outer cover, possible something else was involved but it works

[a101960]

 I have spent a lot of time on this box, all week in fact and I am having no success at all with it. Any one got any ideas about what to look for now? The gearbox indexes fine going up. 1, 2, 3, 4 the shift pedal centralises after each shift ready for the next gear to be selected. Going down this is not happening the pedal does not return to centre so it is impossible to change down.  I can select 3 down from 4 and the change is absolutely fine, but that is as far as I can go because the pedal then sticks and does not return to the centre position when changing down. I have replaced the spring with a new one but this has made absolutely no difference, In fact I shall almost certainly take it off and refit the old spring because the new spring is not as good in its action as the original that I removed. The pedal feels more floppy with the new spring.

Check for wear on the selector claw and quadrant.

From Julian S. Julian both changed Julian

Solved this on my bike by using  two gaskets on the outer cover, possible something else was involved but it works

From bsabill I have ried that and it makes no difference, but the condition does get worse when the box is tightened up. I have played with everthing that I can think of I just don't know what to try anymore.

Earlier you said that you fitted a new quadrant arm, so you had to remove the gear change inner bush?
Did it go back in properly ?
If you loosen the outer cover a little does the gear change return to centre?

From Chaterlea 25, John, on loosening the outer cover sometimes there is an improvement, and I thought that bsabills remark about using two outer cover gaskets was worth exploring. Unfortunatly this does not work for me. I have cheecked the bush and it appears to be pressed fully home.
John

[JulianS]

Is your selector claw on the rightway around - cannot be sure from you photos but looks like it it is wrongly assembled.

Photo below shows the correct assembly.

[chaterlea25]

Hi,
Could you list again all the parts you changed? (again)
I would try and refit the old parts one at a time and see if the problem goes away

As for the gear change shaft sticking, remove the claw and return spring from it,  and refit it and tighten the cover
then see if the shaft is free to turn with a little bit of end clearance

John

[a101960]

Spent all day working on the gearbox again and I took Johns advice about changing back to the old parts. Well, wouldn't you just know it. Put the old worn claw back on and the old return spring and every thing works as it should. The new return spring definately is much weaker than the old spring so that will be returned to the vendor. The Claw. What can I say? That was the deal breaker, I had a slight improvement when I changed the return spring, but putting back the old claw is what did it. It now goes click, click, click, through the gears and the shift pedal centres itself between changes just like it should. During the process of sorting all of this out I also had to take the clutch off. So now a new problem. Refitted it and torqued it up to 65 ft/lbs and now the inner drum is quite stiff to move. It moves easy enough with a spanner on the nut any suggestions as to why this happening? Will it free off of its own accord. It moved much more freely before I removed it I might add. Thankyou everybody that has helped me with your generous advice and suggestions, This saga has been going on for while, so thank you all for your forbearence too. It is much appreaciated. So much for new relacement parts Eh? Ah well such is life.
John

[chaterlea25]

Hi John,
Which type of clutch is fitted to your A10?
Is the chainwheel free to turn easily on its bearing?
The clutch shaft adaptor could be catching on the sliding plate?
Has the inner chaincase been bolted against the frame rear mount without the spacer (washers)
this could be pulling the inner case out against the adaptor
On a 4 spring clutch the inner drum spline can get damaged where it sits against the adaptor forcing it inwards to
pinch the roller bearings
Are the roller bearings the correct length, 6mm as near as damm

John

[duTch]

 If it ain't broke, don't f.. it        (.... fix it) but now you have more mechanical knowledge than you thought you had

 Re turning the clutch centre-  If the drive chain is removed  (if attached cancel thought ), is the box in neutral? 

[a101960]

Which type of clutch is fitted to your A10?
Is the chainwheel free to turn easily on its bearing?
The clutch shaft adaptor could be catching on the sliding plate?
Has the inner chaincase been bolted against the frame rear mount without the spacer (washers)
this could be pulling the inner case out against the adaptor
On a 4 spring clutch the inner drum spline can get damaged where it sits against the adaptor forcing it inwards to
pinch the roller bearings
Are the roller bearings the correct length, 6mm as near as damm

John, once again you got me thinking. This very embarressing to have to own up to. The clutch problem was caused by fitting the inner chain case on the wrong side of the rear frame mounting point. How was it possible to do such a thing? I really don't know, but some how I managed to do it. Clutch working properly now just got to screw the other bits a pieces back on (front chain case, exhaust ect) and then try it out on the road.
John

[chaterlea25]

Hi John
Glad you have found the problem
You are not the first or last person who has tried to do the same

John