Gear linkage position

[Mike_P]

A bit of advice please ! I've had my sprocket casing off today and obviously the small gear change one too. whilst cleaning them before reassembly i unintentionally rotated the change wheel to the right of the linkage a few clicks and I'm not sure what its original position was. Is that critical ? do the marked lines in the circles in the pics attached need to line up ? Thanks in advance !
Mike

 

[Vince]

Horizontal.

 

[Rob]

P66-70 of the workshop manual in the library should help.

 

[Mike_P]

Thanks Vince/Rob, I’ve just found it in my Tim Parker manual !
Cheers Mike

 

[Mike_P]

Well I’ve got the casings back on and just doing a dry run (ie not put oil back in yet)…up and down the gears and rocking back wheel to help changing. It finds them all fine including neutral but it does find a few false neutrals along the way….would that be expected without the engine running/bike moving on these ?
The gear lever return spring doesn’t feel all that strong either although it is returning, maybe that’s part of the problem.
Any advice appreciated as ever thanks

 

[Rob]

Yep, things can feel quite 'crunchy' without the engine running but I wouldn't expect you to find 'a few' false neutrals.

Can you explain in a bit more detail what happens when this occurs? When does it occur (which gear; going up or down; how do you get the gear to engage)? Have you adjusted the eccentric to get equal movement of the hooked selector arm up and down? Usually best done in 4th gear. Loads of stuff has been posted about gear change selection issues - for example this

Have you tried to tap/lever the gear change lever cover forwards as you tighten it? Although your problem may be a weak spring, binding of the selector shaft in the cover might cause a similar symptom.

 

[The Sock]

Weak return springs do make the gearshifts much less precise.
Sent you a DM.

 

[Vince]

One of the blokes here put me onto a mod I am going to try, that spring has 2 points of contact. On my bike, one of those has a substantial gap that allows more gear lever movement than needed. If you use a lathe to take out a couple of mm from the eccentric's diameter only where the spring hits it, you end up removing that slop from the gear lever, and it also helps locate the spring better. I will do it soon.

 

[Vince]

Bent leg of the spring should be on top. That spring legs can interfere with the action and hit stuff they shouldnt, another befit of that lathe added grove you can do to the eccentric.

 

[piranha-bro2]

Tapping the cover to reduce play between the two selector cogs before fully tightening the four cover screws can help. The big spring should have a strong return. They can fracture before breaking (on a ride!), so maybe worth replacing now?

 

[Mike_P]

Many thanks for all the help and advice folks.
Its mainly up and down between 4th and 5th. I've ordered a new gear lever shift spring, i think that's the problem. The gear lever doesn't spring back sharply although it does return....so I'm sure its the pivot spring. If I help it a bit it changes gear okay, I've tried cleaning/greasing the lever pivot but that hasn't fixed it....so I'll try the spring and see if that cures it along with your tips !

 

[piranha-bro2]

Many thanks for all the help and advice folks.
Its mainly up and down between 4th and 5th. I've ordered a new gear lever shift spring, i think that's the problem. The gear lever doesn't spring back sharply although it does return....so I'm sure its the pivot spring. If I help it a bit it changes gear okay, I've tried cleaning/greasing the lever pivot but that hasn't fixed it....so I'll try the spring and see if that cures it along with your tips !

Does the slow return only happen when the triangular cover is fitted? If so it is probably binding on the gear lever shaft mech. I always dummy-fit mine without the gasket to ensure there is enough lateral freeplay once bolted up. You'll see clearly from the gap between outer cover and inner cover mating surfaces if the (approx) 1mm thick gasket is going to eliminate the poss of binding. Basically, you should be able to feel some lateral play in the lever shaft once the triangular cover is bolted up tight.

 

[russo011]

Hello Mike, had the same issue many a time, needless to say adjustment of the selector spring arrangement is very sensitive.
I've not ridden my bike since last May, due to a number of reasons, anyway today 1st gear was as usual, however gearbox was full of false neutrals all the way up from there.
Small adjustment on the offset post cured the issue, such a pain that the cover needs to be removed (oil drain) to access.
The best advice I had is that the spring needs to make contact on all 4 places (2 on the post & 2 on the plate) to work well.
After this morning's fettle everything was as it should be - enjoy

 

[Mike_P]

Does the slow return only happen when the triangular cover is fitted? If so it is probably binding on the gear lever shaft mech. I always dummy-fit mine without the gasket to ensure there is enough lateral freeplay once bolted up. You'll see clearly from the gap between outer cover and inner cover mating surfaces if the (approx) 1mm thick gasket is going to eliminate the poss of binding. Basically, you should be able to feel some lateral play in the lever shaft once the triangular cover is bolted up tight.

I’ve been having a play with it today. Bloody frustrating, it’s almost there but I still have to help the gear lever a bit. I feel the lateral position of the spring plays a part. There’s old spring was very tired, the new spring is much stiffer but messed with all the gear changing when first fit. There’s a small lateral play in the lever so I don’t think that’s binding. I’m going to machine a small groove in the adjuster cam to maintain the spring legs in position.

 

[Mike_P]

Hello Mike, had the same issue many a time, needless to say adjustment of the selector spring arrangement is very sensitive.
I've not ridden my bike since last May, due to a number of reasons, anyway today 1st gear was as usual, however gearbox was full of false neutrals all the way up from there.
Small adjustment on the offset post cured the issue, such a pain that the cover needs to be removed (oil drain) to access.
The best advice I had is that the spring needs to make contact on all 4 places (2 on the post & 2 on the plate) to work well.
After this morning's fettle everything was as it should be - enjoy

Thanks I’m getting there slowly, it’s not the best setup I’ve ever worked on I have to say, when I first replaced the old spring I couldn’t get any gear until I started adjusting it !

 

[russo011]

Thanks I’m getting there slowly, it’s not the best setup I’ve ever worked on I have to say, when I first replaced the old spring I couldn’t get any gear until I started adjusting it !

Yep, it's possible to bend the spring to get the contact as previously mentioned. That way adjustment of the post is a lot more effective.
I tried everything before, including sourcing of a complete exchange cover + mechanism.
I feel for you, however, the sweet spot is possible to find

 

[piranha-bro2]

I’m going to machine a small groove in the adjuster cam to maintain the spring legs in position.

Rather than stress the spring by reshaping it under duress, you can grind very small increments off the tang that holds the spring legs apart so that you get the four points of contact mentioned by Russ. The groove mod definitely works as well. I 'double insure' by fitting a thin stainless shim plate over the eccentric that totally eliminates any possibility of the spring leg getting into places its not supposed to. Once the groove is done, the shim plate is effectively redundant - but why chack it when you've already made it

 

[Mike_P]

Rather than stress the spring by reshaping it under duress, you can grind very small increments off the tang that holds the spring legs apart so that you get the four points of contact mentioned by Russ. The groove mod definitely works as well. I 'double insure' by fitting a thin stainless shim plate over the eccentric that totally eliminates any possibility of the spring leg getting into places its not supposed to. Once the groove is done, the shim plate is effectively redundant - but why chack it when you've already made it

View attachment 104354View attachment 104355

Thanks that’s exactly what I meant ie the groove in the adjuster cam as the tang doesn’t currently touch the spring, so removing material off that would actually make it worse. The groove should allow the spring to get its 4 points of contact.
I like your shim idea….the groove should hold the ends laterally too but if it still moves I can try the shim

 

[Vince]

My next mod, I have maybe 10 to 15mm of freeplay where my toe touches. With a little lathe work, I am hoping to get a Mouser-like gear change. Even a 303 would be ok. Last year, when I discovered my cracked and broken spigit from a tipover doing a U-turn on the side of a steep hill, the inner cover got replaced, and I also replaced the vertical hook gadget with good secondhand bits. It doesn't take much wear to missaline this stuff. 40 years of banging gears tends to do that.

 

[sfcpiet]

If the shift lever doesn't fully return to the middle position despite all the adjusting, ie, needing a tap to be able to find the next gear, the pawl will be resting on top of the pin of the selector drum instead of hooking around it. This can be cured by removing a couple of 0.1mm from the tip of the hook, allowing the pawl to slip over the pin. The hook is almost 1mm "deep". It doesn't need to be this deep to locate securely over the selector drum pins. A simple 30 second remedy. Don't try to file it, use a grinding wheel of some sort...

The position of the eccentric adjuster is also vital. The eccentricity shoud be turned as far away from the mechanism pivot as possible. Turning it closer to the pivot limits the entire up-down movement range considerably, which is bound to cause false neutrals galore.

piet