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jaffa90

Joined:

Mar 09

Posts: 8816

jaffa90 says:

I PAID £643 FOR A BRANDNEW ONE IN 1973

It was the biggest pile of sh*t i`ve ever bought.

http://www.ebay.co.uk/itm/Norton-Commando-750-/251121659721?pt=UK_Motorcycles&hash=item3a78046f49

The bike dropped to bits with the vibration.

The mind boggles,people have more brass than sense.:wacko: 

Mine was the best out of 3 mates who had them.:wacko:

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  • Posted 2 years ago (05 August 2012 23:15)

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brutale r

Joined:

Dec 07

Posts: 3244

brutale r says:

crap

jaffa your talking crap nortons only vibrated on tick over

once the revs went up the isolastics took over ..in its day the smoooothest bike on the market thats whys was known as the first sports tourer

rode a 750 and 850 all over europe verey somer  for 7 yrs raced norton at the TT and nw200 iom gp

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ManxNorton

Joined:

Oct 02

Posts: 180

ManxNorton says:

Vibrator

Motorcycle designer Bert Hopwood came up with the original 500cc Norton Dominator engine.

In his book 'Whatever happened to the British motorcycle Industry', Bert says he was very disturbed to see that his original engine was stretched and stretched again from 500 to 600 to 650 to 750 and finally 850cc.

A stretch too far?

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KrismusSikpunz

Joined:

Mar 12

Posts: 1286

The vibes were isolated from the rider thanks to

Dr Stefan Bauer, mining a rich seam of fundamental engineering principles (as opposed to sitting back on decaying racing laurels), was unhappy with the Featherbed and was quick to point out a number of its failings—not least that it did little to soak up the crippling vibrations pulsing out from every stroke of the Atlas’s crank; vibes that were becoming increasingly problematic as Bert Hopwood’s original 500cc design had been blown out of all practical proportions and had therefore became something of a Frankenstein’s monster.

These vibes, opined Bauer, could however be tamed/minimised with a new chassis; a chassis that would dangle the engine, gearbox and driveline from a single top tube and would control lateral (sideways) movement by a trio of rubber bushes placed at the top, front, and underneath. Torsional (or twisting) stresses would be largely controlled by the top tube itself. The trick was to allow the engine/gearbox/driveline sufficient fore and aft movement, but without allowing it to transmit the bruising vibrations through to the rider.

Exactly how much each member of the team contributed to this new “Isolastic” design isn’t clear. Suffice to say that between these highly talented engineers came the 750cc Norton Commando, claimed by some to be the finest British parallel twin ever, bar none.

The bugbear with this Isolastic system, however, lay in the adjustment. Each rubber bush required careful and precise—and difficult—shimming. If too tight, the engine/gearbox/driveline would lock solid and send the vibes straight into the chassis. If too loose, the lateral movement would become uncontrollable and potentially dangerous.

But what’s with this driveline business, anyway? That’s simple. Merely containing the engine and (pre-unit) gearbox between three rubber mounts would leave these components pulling against the drivechain when under load. That in turn would overstress the rubber bushes creating various action/reaction problems. The solution, therefore, was to mount the swinging arm (and therefore the driveline) directly to the gearbox and suspend that with the three rubber mounts and the shock absorbers.

And it worked. Moreover, isolating the engine from the rider effectively liberated a lot of otherwise inhibiting power.

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jaffa90

Joined:

Mar 09

Posts: 8816

jaffa90 says:

crap

no crap brutale r,

mine was the best crap of the bunch,engine shimming and chain adjustment after every ride,number plates,flashers,oiltank mountings cracking,fork seals pi**ing oil out,exhaust downpipes floating away from the engine umpteen times,speed wobbles at 70mph plus,zener diodes packing in,floating brake caliper seizing up,all welded frame joints lost paint and rusted, 

also mine was the only one where the BIG ENDS didn`t fail,:shock:

I think they were designed for women(brutale r looking at your avatar) to give them an orgasm.:shock: :tongue:

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ManxNorton

Joined:

Oct 02

Posts: 180

ManxNorton says:

Solution or no solution?

Dr Stefan Bauer's design solution, IMHO, masked the fundamental vibration problem with the Commando engine.

But not completely masked as some of our contributors e.g. jaffa90, who have owned Commandos pointed out.

Dr. Bauer was indeed skating on thin ice and sadly, he ultimately paid the price for doing just that.

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KrismusSikpunz

Joined:

Mar 12

Posts: 1286

Another snippet from the experts

The bugbear with this Isolastic system, however, lay in the adjustment. Each rubber bush required careful and precise—and difficult—shimming. If too tight, the engine/gearbox/driveline would lock solid and send the vibes straight into the chassis. If too loose, the lateral movement would become uncontrollable and potentially dangerous.

But what’s with this driveline business, anyway? That’s simple. Merely containing the engine and (pre-unit) gearbox between three rubber mounts would leave these components pulling against the drivechain when under load. That in turn would overstress the rubber bushes creating various action/reaction problems. The solution, therefore, was to mount the swinging arm (and therefore the driveline) directly to the gearbox and suspend that with the three rubber mounts and the shock absorbers.

 

There was little time to develop a brand new engine (Norton had already been struggling with an earlier double overhead cam twin project known as P10, but had failed to make it sing and dance). The only real option, it was suggested, was to rework the existing 745cc Atlas powerplant—with a reputation for serious vibration.

 

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enfieldturbo

Joined:

Jun 12

Posts: 583

enfieldturbo says:

at the

end of the day buy Japanese you can`t go far wrong :wink:

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ManxNorton

Joined:

Oct 02

Posts: 180

ManxNorton says:

Going Japanese - you can go very wrong

Buying a Japanese bike does not guarantee a trouble free motorcycling life.

For example, a fellow apprentice became utterly distraught every time his Honda CB250 (the original red/white K0 model from 1969/70) needed yet another carb diaphram, as it had split, and Honda were taking most of his miserly apprentice wages; who was so turned off by the experience that as soon as he passed his test,he bought a new Triumph T100.

Nobody can ever forget the total disaster that the early Honda V4's were and much more recently we have had the dubious saga of the ST1300 weave, (which has apparently been 'magically' fixed from 2008 onwards).

Yamaha, Suzuki and Kawasaki have also all had their share of clunkers over the years. Only Bridgestone's were practically faultless and the other four soon forced them out of the motorcycle business.

The only sensible advice seems to be to wait for a year or two when a new model comes out and see if any problems surface.

Having said that, I ignored that advice when the Honda ST1100 came out in 1989/90 and I'm still riding it today.

PS. Also, it is entirely possible for a bike to be a very good model at the outset and then 'go bad'. For example, the admirable little Honda CG125 went off the rails in 2004, when inexplicably (according to its Wiki entry) , Honda, revised the model and dumped the fully enclosed final drive. Doh! Or production of a previously sound Japanese motorcycle model shifts to another country and quality problems then begin to surface, which has happened.

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babyrocket

Joined:

Aug 11

Posts: 3732

babyrocket says:

642 quid

too much if you ask me, for a bike that shook like a shitting dog, how can they increase in value when in the first place they were absolute total shite, no wonderb the japanese suffocated the life out of the brit bike industry when they produced shite like those things.

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ManxNorton

Joined:

Oct 02

Posts: 180

ManxNorton says:

Earls Court show 1968 ...

... and the Commando is a 'star' of the show.

I had already had lots of 'experience' with British bikes and I recall walking straight past the Commando to drool over a 650cc Mercury, being very lonely tucked in away in a corner.

I even got a sales leaflet for the Mercury and quite envy a chap in Australia who bought one brand new and which is still giving him good service today, some 44 years later.

Somehow, the Commando must have tapped into something in the typical British bikers mindset or it would'nt have kept winning that MCN poll year after year.

Presumably that long dormant ideal is the reason for the latest Commando - a new design - a very tough thing to succeed at but Bloor managed it with Triumph so maybe Garner and his people have a chance.

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