Can a Norton engine run without vibration?

What I'm asking is can it be self balanced in any way kind of like the modern engines? I just am wondering if it could be accomplished? Curious and if so why didn't they do it? May be a dumb question, I'm not a mechanic.

Dave
69S

That's a relative condition for any engine but check out this innovation for less.

post103910.html?hilit=3rd%20piston#p103910

I thought they did ! . The old balance factor gets a vibration free range at certain rpms, and a not so vibration free rpm range .
Why , I can remember you could stand a half crown on edge on my Rolls Royce Engine , and the Packard V 16 . As they used to say . Endlessly .

The rubber consistancy in the ISO's sould absorb the ossilations at all but a certain rpm range . (1800). I presume NEW theyre a bit harsh , but after a few thousand miles have softened a notch ,
giveing no noticable transmission of vibration rideing out on the highway . Harsh chatter at the bars turned out to be ' road shock ' with the stiff front fork action on bumpy chip seal .

Ye Olde Commando , with a Crank Shaft balance factor of 50 % ( 50% of whats at the other end of the conrod ) presumably osscilates equally for & aft / up & down , on the rubbers .
going for a Balance Factor of 72 % would preumably decrease the vertical & increase the longitudinal ' osscilation ' .

The Dreaded ' 90 degree ' cranks were concieved to overcome inirtial irregularities . The Crankafts tendancy to stop , as the pistons ended up at the ends of the stroke,having to change direction .
Crank pins at 90 degrees have one piston at full speed , mid stroke. The inirtia throwing the other piston over tdc & bdc . tecnically smoother and less power loss and less crankshaft / crankcase
loading / stress. Getting tecnical they position one piston mid stroke , the other tdc ( or bdc ? ) and set the crank ange ( big end offset) where it falls.A few degrees less than 90 .
But being smart , we can set it at 45 deg like a XR75 Harley , 50 deg like a Vincent , or any dang place at all .
If the crank pins were in line , for and aft . ( on the same crankpin ) It'd run very smooth , but like the 180 deg crank , we get a bit a rockin .

Id get tecnical and get the rockin groovey , rather than having it run like a refrigerator .Studying little puffs where the tyre meets the track , on dirt track ovals would be a good start .

Isolation is not same thing as inherent or active vibration cancellation. Nortons inherently need isolation to tolerate after idle. I had the P!! 750 so know what I'm missing and glad of it.

DogT said:

What I'm asking is can it be self balanced in any way kind of like the modern engines? I just am wondering if it could be accomplished? Curious and if so why didn't they do it? May be a dumb question, I'm not a mechanic.

Dave
69S

Click to expand...

I believe the only way for a parallel twin is a balance shaft, which the new Norton has thanks to Kenny. But you have to redesign the crankcase which is why the old factory went with the isolastic solution.

Why you ask, if your bike vibrates too much you need to adjust it.

Thats where these 76 degree cranks come into it too. (gives it almost a v-twin firing order).

Instead of both pistons thumping up and down together, by phasing them out a bit, they counteract each other - but don't then tingle like a 180 degree crank would (one piston up, one piston down, fully opposing each other).

Whether 76 degree cranks go with isolastics is an interesting question though, not sure we have heard anyone try that combo ? Usually solidly bolted in the frame...

Rohan said:

Thats where these 76 degree cranks come into it too. (gives it almost a v-twin firing order).

Whether 76 degree cranks go with isolastics is an interesting question though, not sure we have heard anyone try that combo ? Usually solidly bolted in the frame...

Click to expand...

I built one, it shook less at low rpm but felt kind of like a 4 cylinder at high rpm. Made my hands numb. It was not for me. The bike also had a isolastic head steady that may have contributed to the buzz. Jim

Id prefer a Horse that Galloped and Cantered . Id fit a balance shaft to a refrigerator , not a motorcycle .Prefer RATO to ES

The cam spins backwards compared to the crank. And seems not to be individually balanced.
Anyone ever calculated how much balance shaft affect is there ?
Only spins at half engine speed though, so the effect may be somewhat patchy !

Some bikes spin things like the alternator backwards, which can assist in these matters.
(Not that the alternator itself should run out of balance.)

Dewcati's sun the crank shaft backward , to the wheels .Ive always thought throttle chopping would make them chuckable ,
( like rally technique ) contrary to media reports as regards chassis stability .

Cosworth was preoccupied with TORSIONAL vibration when he designed the Norton unit , ( Pun ? ) immediately after theyd resolved two years cam drive disintegration caused buy Id say cumulative / harmonic load accumulation .
They resolved it with a ' Quill Shaft ' drive .
The Challemnge had them everywhere .
Id bet Quantil spent a bit of time ' fine tuneing ' the things .

See the Charging problems post ? Why'd they drop magnetos . A headlamp connected direct to the alternator works o.k.

Easy to get caught in tecnology for tecnologies sake . Nobody seems to up on ISO lastic refinement , tuneing & development
(and I dont mean the ADJUSTERS ) wonder what peter Williams thinks of its POTENTIAL . Developments Obviously NEAR Zilch .
Tecnically , useing crank throw offsets to UTILISE ' impulses ' rather than CANCEL them ( requireing further force , a LOSS )
will get the thing humming . Bit of a freddie Dixon exercise Id think . Chapman thought less than 20% of Gross Turnover
invested in R&D would be entripical .

swooshdave said:

Why you ask, if your bike vibrates too much you need to adjust it.

Click to expand...

No, I was just curious if the old engine could be made to balance itself and thus avoid all the vibration issues despite the isos. But why wouldn't they have done that in '67 if it were easily do-able? I thought maybe there was some magic mechanical stuff that's been discovered in the meantime.

Mine seems to be settling down quit a bit now, but think I'll get the Hemmings adjusters this winter. The 4K buzz is gone off the bars and footpegs, probably the isos settling in.

Dave
69S

Can a Norton engine run without vibration?
Yes! Mine does at 3200 and 5000rpm

Don't confuse isolation with innate balance, not the same thing even if felt the same to riders. I guess no one has noticed my remarks about rump rod + helpers totally disappearing Ms Peel from pilot sensation but for the thrust and the wind spreading my grin. When I got last rod installed all the mixing and splashing of road wind and engine vibrations resolved into each individual component passing though as if transparent, uncanny flabbergastlingly fabulous. I now and then reach down to feel primary at illegal speeds just to see how much I'm missing out on.

Don't confuse gyroscopic rotation with smoothness, not the same thing either. Peel gets air borne sideways so gyroscopic precession is a concern to me and will see what happens with alternator spun backs to everything thing else.

The British Boxer engines stolen by others is example of inherently balanced engine, but takes a 4 banger because there is still horizontal vibration with the pistons offset on crank center some for rods to clear each other. Inline 6's are another example.

So here's another question that combines both isolation and innate balance, do C'do's the rubber cushions help protect engine jerking itself apart or adds to the engine banging jerking loads?

Matt Spencer said:

with a Crank Shaft balance factor of 50 % ( 50% of whats at the other end of the conrod ) presumably osscilates equally fore & aft / up & down , on the rubbers .
going for a Balance Factor of 72 % would preumably decrease the vertical & increase the longitudinal ' osscilation ' .

Click to expand...

Who can qualify this 50% balance factor being equal "fore & aft / up & down" ? Has anyone actually done a physical scientific test with a Norton? And does it hold true for solid mounted Norton motors?

The answer to the vibration is lightweight pistons - mine have extra lightening and are down to 170 grams each, bare. I ride an Atlas and smile.

Jim S

There are phone apps now that measure vibration of various things so plan is to do that to compare the worlds cycles sensations. I'm following Jim's advice on his light pistons and upping BF into the mid 70's or more just to find out for sure. I know for sure what a totally isolated C'do feels like, nothing but tire patch adhesion gets through to pilot and frame. Uncanny.
When ya really get going loose and leaned the power pulses of engine and drive train come into play, but few will play that loose to even know about how effective the isolastics are when its all tied together silently yet still compliant to absorb loads of thrust.

DogT said:

What I'm asking is can it be self balanced in any way kind of like the modern engines? I just am wondering if it could be accomplished? Curious and if so why didn't they do it? May be a dumb question, I'm not a mechanic.

Dave
69S

Click to expand...

In answer to your question. A Norton motor can be, and is balanced just like any new single cylinder motor that does not have balance shafts or levers.

A 360 degree twin balances just like a single cylinder motor. Minimum shaking forces are seen at just over 50 percent balance factor. Changing the balance factor will make it shake less in one plane but more in the other plane. [IE-less up and down in trade for more forward and rear or vice versa]. Depending on chassis design it may or may not transfer less vibration to the rider.

The only way to reduce the shaking forces is to reduce the weight of the pistons and rods or add balance shafts or levers. Jim

Who can qualify this 50% balance factor being equal "fore & aft / up & down" ? Has anyone actually done a physical scientific test with a Norton? And does it hold true for solid mounted Norton motors?

Jim S[/quote]

Approximatley 52% will make a motor shake the same up and down as forward and rear -if the motor is hanging weightless in space. If it is bolted into a chassis then the chassis will greatly influence the plane of movement. That is why different chassis need different balance factors.

The rubber biscuits in an isolastic mount are about as close to hanging in space as you can get without doing away with gravity. Jim

hobot said:

Don't confuse isolation with innate balance, not the same thing even if felt the same to riders. I guess no one has noticed my remarks about rump rod + helpers totally disappearing Ms Peel from pilot sensation but for the thrust and the wind spreading my grin. When I got last rod installed all the mixing and splashing of road wind and engine vibrations resolved into each individual component passing though as if transparent, uncanny flabbergastlingly fabulous. I now and then reach down to feel primary at illegal speeds just to see how much I'm missing out on.

Don't confuse gyroscopic rotation with smoothness, not the same thing either. Peel gets air borne sideways so gyroscopic precession is a concern to me and will see what happens with alternator spun backs to everything thing else.

The British Boxer engines stolen by others is example of inherently balanced engine, but takes a 4 banger because there is still horizontal vibration with the pistons offset on crank center some for rods to clear each other. Inline 6's are another example.

So here's another question that combines both isolation and innate balance, do C'do's the rubber cushions help protect engine jerking itself apart or adds to the engine banging jerking loads?

Click to expand...

I know I'll be sorry for asking this, but what does "gyroscopic smoothness: and "gyroscopic procession" mean?

comnoz said:

The only way to reduce the shaking forces is to reduce the weight of the pistons and rods or add balance shafts or levers. Jim

Click to expand...

So the JS pistons and rods will reduce the piston/rod weight, I suppose adding a balance shaft or levers is out of the question in the existing motor?

My original question was really about the inherent vibration in the motor, not dealing with the iso mounts.

Dave
69S

comnoz said:

Jim C said:
Approximatley 52% will make a motor shake the same up and down as forward and rear - if the motor is hanging weightless in space.

Click to expand...

Where does this come from? Who determined it & how?

Jim S