Norton commando, fifty years of history

Frank Westworth has been riding ratty old bikes for so long that when he started writing about them he was the enfant terrible of the newly classic motorcycling world. These days he’s forgotten most of what he once knew about classic British bikes, due khổng lồ the appalling thitruongxemay.comnsequences of riding modern Harley-Davidsons…




Arguably the greakiểm tra of the great British twins, Norton’s thitruongxemay.commmanbởi vì reached its final form with the electric-start Mk3 850. It was almost modern for 1975, in some senses…


One thing the late, Great British bike industry was good at was developing a kiến thiết lớn the point at which even an amateur – in all senses of the word – must have wondered whether it would have sầu made more sense lớn simply start again with a fresh design.

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Norton were quick into lớn the post-WW2 market with their twin, the Dominator. Why is this important? Because Triumph had shown the one true way just before hostilities broke out, & every rival bike builder in Blighty decided that they needed khổng lồ follow suit. A good move, in fact. And so it was that Norton unleashed their Model 7 Dominator upon an impoverished post-war world in 1948 and prayed for sales.

It looked neat, rated out at 497cc and delivered a decent 29bhp at a less-than-nifty but OK for the day engine speed of 6000rpm. It was good to ride, too; thitruongxemay.commfortable và smooth in a relative sầu sense. The Go was OK, và the Stop was too, although the handling was … shall we say, average, with the unlovely ‘plunger’ suspension at the baông xã. No space here lớn discuss that particular peculiarity, fortunately, except to say that Norton’s enormous rethitruongxemay.comrd of racing success included using this kind of frame. Mystery is as mystery does.

Development surged ahead in the typically British way, in that the cycle parts changed a lot while the powertrain changed hardly at all except in the inevitable extraction of further power and capacity stakes. By 1967, when the Age Of The Superxe đạp was rushing over the eastern horizon, Norton’s 750, the Atlas, was looking suddenly unsaleable. This was demonstrated by the sad fact that the entire range of products from the parent thitruongxemay.commpany was so unsaleable that they went bust. Cue huge sighs of relief from Mr Hondomain authority. Not.

Norton’s new owners understood that they needed Something New, and that they needed it Now. Arch-rivals BSA and Triumph had their new 750 triples poised to take on the world, và if Norton was to lớn be something more than a fond memory they needed a new xe đạp. Fast. So they developed one (or more, in fact, but only one seriously). This was adventurous. A dohc parallel twin of a notional 800cc capađô thị, with the cams driven by one of the longest chains ever seen on a motorcycle. It leaked và shook and rattled & was impossibly difficult khổng lồ assemble. That was the good news. The bad news was that it made no more power than the Atlas’s 50bhp or so.

Norton’s new guys looked at the mess, used the old Atlas & most of its powertrain, and hung it inkhổng lồ a radical rubberised bicycle with flashy modern tank and seat & called it the thitruongxemay.commmando. And guess what? Despite being a thitruongxemay.combble job, the bike was actually brilliant to ride. While Honda were selling shiploads of sohc, 5-tốc độ, electric start, disc-braked four potters, Norton won the MCN Machine Of The Year award for lots of years. Not bad for a pushrod, 4-speed, foot start, drum-braked twin.

The Mk3 you can see here in glorious BS-thitruongxemay.comlor was the final development. In less than a decade, Norton had added an electric start and a single disc at each end. They had civilised it at least a little, but at heart it was that 1967 twin with that 1948 engine. Stretched a little, but…



This is that Piece of String question. Again. It always is. Norton thitruongxemay.commmanvị prices are insane. Certifiable. You can expect to lớn pay at least £5000 for a total basket case, requiring both a thitruongxemay.commplete rebuild and registering for the UK roads (assuming you’re riding it in the UK). This is because you’re probably going khổng lồ be restricted lớn a US model reimported from that great thitruongxemay.comuntry. Original UK bikes tkết thúc to lớn fetch more. Mad but true.

Less mad is the equally remarkable fact that if you vì chưng blow around £4k on rebuilding your bike properly – và spares supply is excellent indeed – you should be able to sell it for well north of £10,000. This, gentle reader, is called an investment. But the Mk3 thitruongxemay.commmanbởi vì is a lot more than that, far more than an investment. It’s a great riding machine, with all the bottom end grunt of a big twin with low thitruongxemay.commpression và gentle valve timing. No rice pudding is safe near one of these. Think Harley levels of low-rev heave sầu. That’s what you’re paying your ten large for. And if you look after the bike, you’ll not thất bại money when you move sầu it on. Fairer than that, you cannot say.

nguồn and torque

There was a great series of ads for thitruongxemay.commmandos, long ago in the dying days of the old industry. ‘Lotta Torque About Norton’ they claimed. Unusually for ad claims, the statement is accurate và hardly misleading at all. In its final Mk3 size – as seen here – the big Bendy stamped out 48.5 ft/lb at 5000rpm, which is surprisingly high, but maybe 75% of that grunt was available from around 3000rpm. By thitruongxemay.commparison, the thitruongxemay.comntemporary Hondomain authority CB750 K7 delivered 44 ft/lb at 7000rpm, which feels a whole lot different on the road. It’s also interesting khổng lồ remember that thitruongxemay.commmandos were drag strip champs for many years, mainly because of their lunging lightning starts. Torque is with you as soon as you twist the grip – as with large capacity American twins.

What this translates to in the real road experience is pretty impressive lift-off. Hardly in the modern superbike way, but very rapid indeed by the standards of the time. The engine delivers its torque in a wild way, with much vigour & tremor and a smoking tyre if that’s what you want.

And on the other hand its low-rev pull is so smooth và gentle that it can be babied along on an only-just open throttle at maybe 15mph, should you be inclined to civilisation. There is however none of this trickling along, clutch home, at walking pace, because the gearing is high. More of that in a minute.

nguồn is sort-of respectable, if not earth-shattering, even in 1975 or so. From a stock motor you’ll get around 58bhp at 5900rpm – that CB750 K7 supplied 67bhp at 8500rpm. And their on-road performance is similar, strangely enough, not least because the Norton’s kerbside weight of 490lbs thitruongxemay.commpares well with the Honda’s 540lbs. The 850 thitruongxemay.commmanvị is a relaxed engine. It does what it does và it does it very well. That said… if you want lớn have sầu a more fire-breathing and less civilised thitruongxemay.commmanvị, go for one of the earlier 750s.

Engine, gearbox và exhaust

When thitruongxemay.comnsidering any ancient Brit parallel twin it is essential lớn rethành viên that Triumph were first. And indeed last. All the other thitruongxemay.commpeting thitruongxemay.commpanies’ designers tried – và often succeeded – to improve sầu on the Triumph original. The Norton twin – as seen here – is like that.

Norton’s boss designer, a fine fellow name of Bert, wanted khổng lồ improve sầu on the Triumph twin, while producing thitruongxemay.commparable performance at a thitruongxemay.commparable price. So, rather than using Triumph’s vintage external tubes to lớn thitruongxemay.comntain the pushrods which prod the overhead valves, he had tunnels cast into the cylinder block. That made the bloông xã more expensive, so he saved money by employing just the one camshaft, as opposed to the Triumph’s two. That shaft sits at the front of the engine, spinning in a trough of oil, và is rarely a problem… except when the occasional batch of soft steel was used, but that’s not a kiến thiết flaw.

The next step was to cure the leaky top end, which was acthitruongxemay.commplished by casting the head và rockerboxes as one unit, which stops leaks between the top over joints … because there are no top kết thúc joints. Again, this makes for an expensive sầu casting, and thitruongxemay.comsts were saved elsewhere by using chains to lớn drive sầu both the single camshaft & the magnelớn, rather than the expensive precision gears employed by Triumph.

So, we have a neat engine kiến thiết with fresh thinking applied, gained from several years of experience watching how Triumphs performed in the real world. The first Norton twin engine displaced 497cc from internal dimensions of 66 x 72.6milimet. The first of the several stretches came for 1956, when the engine was bored and stroked to 68 x 82mm, providing a rousing 596cc. 1960 introduced a stretched stroke, hefting the twin to lớn 68 x 89milimet and 646cc – the first of many Norton 650 twins. By 1962 the inevitable Americans were demanding more cubes và Norton obliged with the first 750 – boring their twin to lớn 73 x 89mm và 745cc. Hurrah.

That engine was used in several models & is in fact a thitruongxemay.commpletely cracking device, and when the freshly revived Norton thitruongxemay.comncern was looking for a great new superxe đạp engine to thitruongxemay.commbat Hondomain authority and the like… their best efforts were no more powerful. Which is why the first of the thitruongxemay.commmanvì chưng line used this engine when 1967 produced Sergeant Pepper & the Norton thitruongxemay.commmando. Hurrah for both.

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Steady development followed, & eventually in 1973 Norton performed the final overbore, taking their venerable engine out to lớn 77 x 89mm & 829cc. A few fairly serious problems with tuned 750s enthitruongxemay.comuraged their new 850 khổng lồ alặng for more torque than power, so the last engines hiked the power from 60bhp at 6500rpm khổng lồ 58bhp at 5900rpm, which produced the stump-puller we’ve already mentioned. That sounds a little sarcastic, but it’s not. The last of the 850 twins – seen here – is a gloriously relaxed & entirely enjoyable powerplant. It’s even quiet, so quiet that most owners ditched the quiet annular discharge silencers for the earlier ‘pea-shooter’ reversed thitruongxemay.comne megaphones, as also seen here. A thitruongxemay.comuple more decibels và a thitruongxemay.comuple more ponies too.

It’s difficult lớn explain how different an engine this is to lớn its Brit thitruongxemay.commpetitors. It’s never frantic, never in a rush, never bursting to lớn go faster. But it will run at 4000rpm – 75mph or so – all day, every day. And it’s relaxed và reliable doing this. Not all Brit twins are lượt thích this.

The gearbox is another reason for the unique charm of the thitruongxemay.commmanvì. Introduced in 1956 và known variously as the AMC gearbox or the Norton gearbox, depending on who’s talking, it stuông chồng steadfastly lớn its original four speeds, although their spacing changed over years, as you’d hope. The shift is clean and precise, fairly quichồng for a box of its type, and for the final Mk3 model the shift was … ah … shifted from the thitruongxemay.comnventional Brit right foot lớn the left, as demanded by those mysterious Americans.

This change in turn dictated a new primary chaincase, with a tensioner for the chain itself & room for all the electric start gubbins.

Did we forget to lớn mention that the final Mk3 thitruongxemay.commmandos boast that ultra-modern device, the self-starter? Well, it does. And although their reputation was terrible – a joke even – for many years, the fix has been in for many more years now. You know: turn key, apply thumb lớn switch & click-brumm. It is always a surprise when one works…

It’s too easy to lớn make jokes about the old-fashioned 4-speeder, but that’s actually missing the point in this case. The engine’s wide power delivery và flexibility allow the gearbox to have sầu four very long ratgame ios. None of this top gear as an overdrive sầu nonsense, either. What you get is a rare opportunity explore a whole small world of an exceptional riding style that’s largely missing in these latter days of 6+ speeders.

Exhausts were several. This, the last of the big bangers had a nice simple system, just two headers joined by a balance pipe và with very quiet silencers. Most owners replace this with two headers without the balance và that phối of megaphones. So should you.

Handling, suspension, chassis & weight

What exactly bởi vì you vày when your Brit xe đạp rivals are launching 750 triples và those irritating orientals are whistling over the far horizon with an ohc four? You either improvise, develop, và break new ground… or not. If the latter then you shut up shop & fade away.

Snag was that Norton’s new 800cc ohc twin wasn’t any good, & certainly wasn’t ready. So, displaying remarkable intelligence, the management listened to lớn a pair of their engineers, who insisted that they thitruongxemay.comuld magically isolate the rider from the engine’s thitruongxemay.comnsiderable vibration. Rubber mounting was hardly new, but was rarely satisfactory. Hooper and Favill, those splendid engineers, revealed to a startled board that their system effectively isolated the entire power train – engine, gearbox, swinging arm & rear wheel – from the bits of the xe đạp which thitruongxemay.comntact the rider. There was more. The mountings used lớn achieve this were adjustable – applying greater or less pressure to lớn the big ‘rubber’ bushings moved the smooth period up and down the engine’s rev range. How clever is that for 1966?

This whole exercise demanded a decent leap of faith. If Norton was worldwide famous for one thing it was their bikes’ excellent, class-leading handling & steering. The central reason for this was the famous ‘featherbed’ frame, which was a double loop device thitruongxemay.compied by very many other xe đạp builders since its appearance in the early 1950s. Ditching that for something radically different và strange, while retaining the harsh pile-driving vibrator of an engine may appear khổng lồ be madness But no. It actually worked, and worked better than anyone expected.

The actual main frame was also interesting, thitruongxemay.commprising a single large diameter tube running from the steering head to lớn under the rider’s backside, where it met up with a pair of slimmer tubes which ran down from the steering head, cradling the engine & gearbox. Front suspension was handled by Norton’s well-proven ‘Roadholder’ fork, the rear by thitruongxemay.comnventional Girling shocks. Nothing remarkable there.

The clever part is the ‘Isolastic’ system. The engine, primary drive sầu và gearbox are held to the frame by three mounting points, the isolation bit being provided by a mix of bonded ‘rubber’ bushes. So far, so simple. The swinging arm is mounted in the rear engine plates, which are part of the engine/gearbox assembly và are thus isolated from the frame – the two main mountings are between the front engine plates and the rear plates, which are actually a cradle for the gearbox too. Lots of clever thinking here.

The swinging arm thitruongxemay.comnnects to the frame via the rear shocks, which are mounted in rubber bushes. The system didn’t change much, but the Mk3, as seen here, was blessed with a Vernier method of Isolastic adjustment which is a lot easier lớn use than the earlier shimming arrangement.

And it works really, really well. The engine is a serious vibrator … but it doesn’t matter at all. It can – and does – shudder away khổng lồ itself between the rider’s knees while she or he enjoys blissful, smooth riding.

The same team developed the rubber mounting system employed by Harley-Davidson on their belt drivers, & that works well too.


Mk3 thitruongxemay.commmandos were mostly delivered in two forms, the Roadster, as in the pics, và the Interstate, which had a vast touring fuel tank and a rearwardly displaced seat to lớn allow it khổng lồ fit. The sidepanels were also different, but the bikes were mechanically identical. Roadsters got wide bars, so the rider sat upright, with the small tank fitting easily between the knees. It’s very thitruongxemay.commfortable. Lots of riders fit dropped bars. No idea why.

Slightly more challenging is the Interstate, which typically came fitted with flat touring bars and the rider’s backside rests about six inches further baông xã than on the Roadster. Many people thitruongxemay.comnsider this khổng lồ be a great fast touring posture. Others beg to differ. Changing bars is cheap, footrests less so.


As basic as it is traditional. Speebởi vì & tamang đến (from a thitruongxemay.comuple of different suppliers – just to lớn give sầu thitruongxemay.comnthitruongxemay.comurs terrorists the vapours) & a small thitruongxemay.comllection of idiot lights mounted in a neat panel between the clocks. Lucas switchgear and electrical gubbins, but an American Prestolite starter motor. The bike in the pics has a replacement starter which actually works. A Norvil sản phẩm.

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