18CS Replica Chain Rub

[AMacD_LAPSED]

Edit: Sorry the photos weren't visible. Hopefully fixed now?

Hi all,

I've recently bought this this bike:

18CS.jpg

Getting the bike just before lockdown I've had little opportunity to use it, so am decidedly in the 'getting to know it' phase.

It was described as a 1956 18CS Replica and to my inexperienced eye looked basically correct. However, based on what I've learnt since I think there are some spec anomalies. For instance the engine is I think the earlier long stroke version but it has the later alloy primary drive chaincase and AMC gearbox. I mention this because it might be relevant to the issue I discovered whilst working on the bike yesterday:

I noticed brass fillings on the outer side of the final drive chain. It appears that the chain is rubbing on something around the front sprocket. The following photo is taken between the engine and gearbox:

Chain_rub.jpg

You can see the fretting in the centre of the picture.

Any thoughts / advice would be much appreciated. I don't want to start disassembly without a good idea of what I can expect to find.

Thanks in advance,
Alex

[Mick D]

Hi

There's not normally any brassy component in that area so I can't begin to advise what the issue is. I'd suggest you remove the primary outer case and check there is no conflict between the clutch and primary cases as a start. You're probably going to have to remove the inner primary case to address the interference by either moving the gearbox across, adjusting the sprocket spacer or moving the PCC away from the engine, once we know what's installed it will be easier to advise.

Regards M<ick

[AMacD_LAPSED]

Many thanks Mick. The brass seemed odd to me too!

Will let you know what I find.

Alex

[dave16mct]

Can't see any pictures??
Dave.

[SPRIDDLER]

I can't see your photos but here's a factory promotional pic and technical spec'n of the '56 18CS if it's of any interest.

http://archives.jampot.dk/promotional/S ... ochure.pdf

[AMacD_LAPSED]

Can't see any pictures??
Dave.

Thanks Dave - Hopefully fixed now.

[AMacD_LAPSED]

I can't see your photos but here's a factory promotional pic and technical spec'n of the '56 18CS if it's of any interest.

http://archives.jampot.dk/promotional/S ... ochure.pdf

Thanks Spriddler - nice to see the brochure!

[g80csp11]

Its not unusual if the rear chain is loose for it to just catch the swinging arm , perhaps the shock absorbers have lost their damping and giving excessive movement
The frames are brazed together , so perhaps you are seeing rubbings of braze rather than brass
just a thought !

[Pharisee]

Looking at your second picture, it seems that the final drive chain is rubbing on the back of the primary chain case.

[dave16mct]

I can see them now. It may be that the previous owner made or repaired the sliding seal at the back of the chaincase with brass and the chain is catching it. I wouldn't worry too much about it. Nice looking bike, How does it go?
Dave.