A7 star twin 1952

[KeithA]

Just wondering what the fitting is under the gearbox at the front close to where it bolts to the engine.
Its about a 1/2 inch bolt or tube, and sticks out about an 1'1/4", and has a locknut.
Sorry for the dumb question, but I can't find any reference to it in the exploded drawings I have.
Thanks in advance.
Keith Atkinson

[Greybeard]

This is the detent device that locates the selector cam notches. In other words, it makes sure that the current ratio stays engaged until the rider changes gear.

[trevinoz]

Or we could call it the cam plate spindle.

[duTch]

 Sorry Trev, but I think GB has the call on this

[Klaus]

Hi Keith,

keep them always clean. Over the years the plunger will stick in mud.
There is a little hole at the top of the plunger to allow  them moving in the oil.
Is this hole blocked, the down moving by shifting produce a vacuum inside.
So the spring could not get enought pressure to the camplate.
Result is the gear jump off by accelerat.


cheers Klaus

[Greybeard]

Hi Keith,

keep them always clean. Over the years the plunger will stick in mud.
There is a little hole at the top of the plunger to allow  them moving in the oil.
Is this hole blocked, the down moving by shifting produce a vacuum inside.
So the spring could not get enought pressure to the camplate.
Result is the gear jump off by accelerat.


cheers Klaus

Klaus, are you saying that the gear cam locator, (Detent) can get mud inside? I'm pretty sure mine has no hole in the bottom.

[Klaus]

Yes, the swinging arm boxes have this hole.
It is about 1,5mm
So  l gues the the bolton boxes also.
I have made the experience with shifting off.
The manual sayed there will be only 2threads visible by screwing in.

cheers Klaus

[Klaus]

Have made a picture.

[Greybeard]

I think we may have a language misunderstanding here. I see that hole but that is inside the gearbox isn't it, not on the bottom and exposed to contamination, (by mud?). Maybe you are saying that gearbox oil sludge, (is there such a thing?) can get in there and cause the device to stick?

[muskrat]

Gear control cam plate plunger housing!
By mud Klaus means sludge (oil & fine metal partials).
Without the hole it would hydraulic lock.
Cheers

[Klaus]

Gear control cam plate plunger housing!
By mud Klaus means sludge (oil & fine metal partials).
Without the hole it would hydraulic lock.
Cheers

Yes that's correkt.

Sorry for that misunderstanding

Cheers Klaus