AMC Gearbox seal

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Plugsnpoints
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Re: AMC Gearbox seal

Post by Plugsnpoints »

SPRIDDLER wrote:I'm not certain but from the Spares List I think the standard touring bikes had just the short breather (Release) pipe 000755 pointing down behind the chaincase. Comp models had the extension pipes 018742 and 018743 returning oil mist to the tank.
Vent pipe for breather (640x127).jpg
Vent pipe breather 2 (600x433).jpg
I see, so does that mean my bike is correct, with both the one from the tank, and the other one from the L/H main just vent to the atmosphere? There's a metal pipe that the tank one is fitted to. Mine's just a standard road machine. Thanks Neville. :)


Andy
Mick D
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Re: AMC Gearbox seal

Post by Mick D »

Hi

The breather from the crank case should just point downwards.

The oil tank breather should be a flexible rubber pipe into a metal tube secured to the GB adjuster with a tab - this tube then directs a mist :rofl: of oil at the rear chain. These are from a 61 G3:
Breather pipes.png
Regards Mick
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SPRIDDLER
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Re: AMC Gearbox seal

Post by SPRIDDLER »

Plugsnpoints wrote:
I see, so does that mean my bike is correct, with both the one from the tank, and the other one from the L/H main just vent to the atmosphere?
Yes, Andy, to a purist yours is 'correct' by the book.
Some folk have run the breather pipe to a 'catchpot' to save getting drips on the ground, (which are sometimes mistaken for a leaking chaincase).
I've read the suggestion that routing the breather pipe upwards allows oil to build up in the pipe to the extent that it impedes the free movement of the disc in the crankcase breather, thus preventing it from functioning correctly. I've always had just the short stub as in the book, pointing downwards, so my comment is pure hearsay.
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Plugsnpoints
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Re: AMC Gearbox seal

Post by Plugsnpoints »

Ok, so I have an old piece of chain to hold the sprocket to stop it moving in the vice. I have obviously removed the locking tab.

I just can't shift the sprocket nut. I have a huge bar and a substantial box spanner on it but it won't budge. Someone on here said it has a left hand thread, so I am turning it clockwise to undo. Is this definitely left hand thread? I have to ask as it's not moving.

I've decided to call it a day for now. I've squirted it with ACF50 and penetrating oil and going to leave it to soak for a day. It's not rusty and he thread is clean.


I am considering buying a 38mm 3/4" drive deep hex socket. I measured the nut 1-1/2" across the flats.


Any suggestions please?

Thanks,

Andy
Mick D
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Re: AMC Gearbox seal

Post by Mick D »

Hi

On an AMC 'standard' GB the sleeve gear has a LH thread - can you see enough thread exposed outboard of the sprocket nut to confirm this?

Are you sure you have an AMC GB installed? - The Burman sleeve gears are RH threads - (well at least the three I've stripped were).

And on a long shot - I wonder if it's possible to mix and match AMC / Burman sleeve gears, and thus confuse the issue even more.

Regards Mick
Plugsnpoints
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Re: AMC Gearbox seal

Post by Plugsnpoints »

Mick D wrote:Hi

On an AMC 'standard' GB the sleeve gear has a LH thread - can you see enough thread exposed outboard of the sprocket nut to confirm this?

Are you sure you have an AMC GB installed? - The Burman sleeve gears are RH threads - (well at least the three I've stripped were).

And on a long shot - I wonder if it's possible to mix and match AMC / Burman sleeve gears, and thus confuse the issue even more.

Regards Mick
Hi Mick, I'm pretty sure it's an AMC box. Please can you have a look at the photo.

Thanks,

Andy
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Mick D
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Re: AMC Gearbox seal

Post by Mick D »

Hi Andy

Photos can be deceptive but I'm pretty sure that's a LH thread.

The design of that sleeve gear is also different from the Burman one.

Regards Mick
Plugsnpoints
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Re: AMC Gearbox seal

Post by Plugsnpoints »

Mick D wrote:Hi Andy

Photos can be deceptive but I'm pretty sure that's a LH thread.

The design of that sleeve gear is also different from the Burman one.

Regards Mick
Hi Mick, the sprocket is driven in an anti clockwise direction from the clutch, so wouldn't it make sense for it (the sprocket nut) to have a normal right hand thread?
Mick D
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Re: AMC Gearbox seal

Post by Mick D »

Plugsnpoints wrote:Hi Mick, the sprocket is driven in an anti clockwise direction from the clutch, so wouldn't it make sense for it (the sprocket nut) to have a normal right hand thread?
Yes - On the face of it you would think so - But

I'm pretty sure the most shock load the thread will experience is when changing down and using the engine as a brake, in which case a LH thread is beneficial

Just a theory though ;)

Regards Mick
SPRIDDLER
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Re: AMC Gearbox seal

Post by SPRIDDLER »

My two penn'orth.......(just ruminating)....

If the nut won't shift by heaving with a box spanner and bar until the veins bulge it will sometimes loosen by putting a ring or open ended spanner on it an giving the spanner end a good thwack with a heavy hammer. The shock seems to do the trick. An impact driver/rattle gun is best buy would need a very deep socket. That thin nut seems to be a bit recessed into the sprocket so perhaps there isn't enough meat to get a ring or open ended on it securely.
If you can't determine exactly what the thread is (surely you can?) you could try it both ways as no harm will be done. Even whacking it the 'wrong' way will sometimes break the adhesion. Obviously you'll need to hold the g'box securely. Perhaps bodge up a bit of support for the g/box and clamp the chain in the vice jaws to hold it firm for a thwack or two?
P.S.
As Mick said, photos are confusing but it looks to me that the second thread of the right hand pair of the two threads is 'higher' (has slightly more thread showing above the nut) than the left hand ones where the second thread ring is touching the nut which makes me think it's a r/h thread. :?
Here, picture...........thousand words, so forth:
Sprocket nut snip detail.jpg
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