I recently acquired a 1966 Norton Atlas that apparantly had sat forlornly in the back of a garage since 1972. Yes, that's 50 years untouched! It came with sidecar lugs attached, but no sidecar in sight. I have since stripped it down, put it back together and it runs like a top (no sidecar anymore). Yes, it still has oil leak problems on the primary chaincase but I'm going to attempt the Andrew Westfield mod using a 16" innertube to rectify that (watch this space) Other than that it's a good un.
The primary chain was dry as a bone and was way too loose when I opened up the chaincase for the first time. On purchasing a new primary chain I then discovered from the vendor that 'sidecar models' require a half link in the chain. This bike's chain didn't have that half link hence why it was so loose I guess? Anyway, the new chain with the half link fitted a treat and adjusted up correctly so I assume he knew what he was talking about.
Does anyone have any info on this required 'half link' ? I can't find any literature on Factory Atlas 'sidecar models' anywhere. It's got a slimline featherbed frame which is in good solid condition with no cracks. The forks are the wide type with the steering lock on the top yoke. I can't easily determine if the yoke angle is different in any way from a standard yoke as I don't have anything to compare it to. It also has a John Tickle TLS front brake. All I know is it handles like it's on rails and goes like s*** off a hot shovel so I'm pretty happy with the end result but I'm really curious about it's history.
The bike came with no documentation at all (all lost long ago) but it's been verified by NOC as a bone fide Atlas and DVLA don't seem to have a problem allocating it a new age related number plate either. The old chap who had owned the bike for millenia had dementia so I couldn't get much out of him. But what's the deal with the sidecar thing? Was it originally a 'sidecar model' and if so, what differences are there to the frame geometry other than what I've mentioned above.
The pics show the bike when I got it, the sidecar lugs removed, the half link primary chain and the finished bike all done and dusted.
S/CAR stamping
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The half link may be because…
The half link may be because it has a smaller engine sprocket to lower the gearing for SC use , that certainly will make it lively but a bit vibratory at speed . sidecar yokes were stamped SC but not easy to spot , but if it handles well it probably has std yokes. The engine sprocket will likely be very tight and need a proper puller and some supplied by our specialists are rubbish .
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The bottom curved yoke has…
The bottom curved yoke has the serial number 030342 but no mention of S/CAR anywhere.
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It's possible that the…
It's possible that the engine sprocket has fewer teeth. I think I did count them when it was off but I never made a written note of how many teeth it had. It is pretty lively on acceleration and also a bit vibey top end so you're probably spot on there. I really like the pull and torque in 4th gear though so I'm more than happy to leave it as it is. It's probably only doing 70 - 80mph flat out but on this ol' boneshaker it feels like 120!
That engine sprocket was on really tight but I got it off with a decent three legged puller that I have aided by a 3ft metal bar on a decent socket spanner - and it came off with a mighty kerwaaang!
By the way Robert, that nut you kindly brought into Ardingly for me didn't actually fit the lower gearbox spindle. It turned out to be a 20tpi 3/4 UNF which I got on Ebay, but thanks for doing that anyway.
p.s. How many teeth should a standard Atlas engine sprocket have? I'm going to take the primary chaincase off again soon so I'll check how many mine has then
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That do look a proper bike !…
That do look a proper bike !.Very practical and begging for a ride. We fitted a sprocket with 1 tooth over std to try to reduce the vibes , If you have had the head off check the bolts a few times as they come loose. Also watch out the primary chain does not tighten up the first time you give it some stick .The box gets pulled back by the rear chain.
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I have a later 7 3/8"top yoke, which is prominently stamped S/CAR, directly on the front. I don't have a corresponding bottom yoke, but I imagine that would carry the same stamp.