Featherbed frame design went against all engineering princip

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Re: Featherbed frame design went against all engineering pri

The 350 manxs had thinner walls than the 500 versions !
Manx frames are not the same shape or dimensions as road bike featherbeds,
if you compare them side-to-side.

The local frame repair guy here, who had formal HD training on frame repairs, commented that featherbeds usually require tweaking back into spec in quite a few places - so they shift considerably with hard use. The wideline I acquired had had the full treatment (unbeknown to me !) and he said it was out almost everywhere it could be. His frame jig weighs probably tons, and he just hauls em back into line....

He also owns a Norvin (Vinnie motor in featherbed frame), custom made featherbed - his build,
and the motor sits lower and deeper than the usual Norvin.
He reckons thats how they need to be to get proper weight distro.
It also has been built so a Commando interstate tank sits neatly on top.
 
Re: Featherbed frame design went against all engineering pri

The earlier featherbeds as used with the long stroke engines had a bolt-on rear subframe. I like them better. I believe all of the manx frames were made out of Reynolds alloy steel tubing, I don't know about the slimline ones. There are plenty of replicas around which have been made out of mild steel tube. They are OK as long as you don't want to race with them for decades. The common trick is to change the rake from 24.8 degrees to 26 degrees to suit 18 inch wheels. I believe the better rubber might make them crack a bit earlier.
 
Re: Featherbed frame design went against all engineering pri

Very good Allan, you actually have most of the basic facts correct - for a change.
But how do you know 'you like them' if you haven't actually ridden them ??

A wideline here is an early bolt-up-rearsubframe-type.
Nortons soon realised that was a potential weakness, and welded them on.
No having the subframe depart mid-ride. !!

acotrel said:
The common trick is to change the rake from 24.8 degrees to 26 degrees to suit 18 inch wheels.
Click to expand...

Where do you get these numbers from though ?
And just how do you 'change the rake' - on a frame !!!?
My book says that the stock steering head angle for widelines was 26 degrees.
And if you measure the angle from photos, it also shows them as 26 degrees.
That is the rolling-on-the-road angle though.
 
Re: Featherbed frame design went against all engineering pri

design went against all engineering princip
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could probably say the same for these . I wouldn't let it worry you . :wink:

Featherbed frame design went against all engineering princip
 
Re: Featherbed frame design went against all engineering pri

When all the oil has run dry,
and all the farms are in ruin from csg extraction,
and the sky has turned black from all the coal we have burned,
Repent Now, for the Kingdom of the Horse is nigh.....
 
Re: Featherbed frame design went against all engineering pri

Matt Spencer said:
design went against all engineering princip
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could probably say the same for these . I wouldn't let it worry you . :wink:
Click to expand...
very interesting history, first i'm hearing
 
Re: Featherbed frame design went against all engineering pri

Cheesy said:
SteveA said:
Some have noted that the Manx frame used lighter tubing, but that tubing also has different flex and resonance characteristics to the road bike mild steel, and the replica frames being made today have different tubing again, and are used with different tyres, suspension and geometry.
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Did the Manx frames have bigger diameter tubes? If not and all other things being equal they would flex more than the road frames.
Click to expand...
Same OD on the tube size, so what you say about flex is correct. The reduced wall thickness with chrome-moly tube will give more flex (elasticity is about the same for CrMo as for mild steel). You can just flex the CrMo further, before it breaks or yields.
 
Re: Featherbed frame design went against all engineering pri

Just to get ultra picky again, 531 is manganese molybdenum steel, not chrome moly.

Same principle applies, of course....
 
Re: Featherbed frame design went against all engineering pri

Rohan said:
When all the oil has run dry,
and all the farms are in ruin from csg extraction,
and the sky has turned black from all the coal we have burned,
Repent Now, for the Kingdom of the Horse is nigh.....
Click to expand...

Hydrogen awaits , its there now..just to much investment in hydrocarbons :!: I have my Commando equiped and ready,no more pesky amals :lol:
HYDROMANDO ..might register the name before anyone else doe's :roll:
 
Re: Featherbed frame design went against all engineering pri

I believe catalytic cracking is used to make petrol from crude oil. It is also possible to use catalytic synthesis to make petrol. I think the Germans were doing it during WW2 and the petrol companies closely guard the information about their catalysts these days. All it means is that riding vintage motorcycles might become a luxury past-time. And we could always use methanol anyway. The combustion product, formaldehyde is now a listed carcinogen. Would that be a worry ?
 
Re: Featherbed frame design went against all engineering pri

Fuel cells are now coming online commercially, new battery ion chemistry and electrode construction that far exceed current offerings and supercapasitors for spikes in power output plus dual motor/drag regenerators with air conditioning compressor all in one wheel power unit for awd traction and steering control with a lot of the frame being part of the energy system. What may extend our vintage combustors next decade might be vapor fuels, propane methane or hydrogen.

Peel's main frame is also oil tank and cooler while swing arm also an air pressure tank. Peel's crash cage may stiffen cdo frame for better off road tolerance but may stiffen the road racing tire conflicting loads too much though. I think the oil mass in frame may act to dampen sonic vibes, which w/o Peel type flexy tri-links will make no sense to the rest of you buzzing and jiggling Cdo riders. Peel's isolation went beyond just engine vibes, which both surprised and spoiled me after my Jaguar and Lexus sedans, which make BMW's and Mercedes cars feel like clunky trucks compared.
 
Re: Featherbed frame design went against all engineering pri

I think the limit of using the rigidly mounted motor was reached with the 650ss . With the Atlas it became all too hard. You end up with a choice of where in the rev range you want the vibration to be. In comparison with the CB750 Honda the Norton was never going to cut it. If you tried to ride my Seeley on public roads, I think you would go spare. Once it is being ridden hard, it is really great - you cannot legally ride that fast on public roads. So Norton had a very big problem and the isolastics were probably a good answer to it. The design runs contrary to everything I've ever tried to do with my race bikes.
 
Re: Featherbed frame design went against all engineering pri

At least for 360" twin thumber's Alan, w/o isolation feel like pile drivers till nose tingles and eye sight blurs and thin metal cracks. Peel has taken me beyond all the normal concerns of isolation and handling to finer details Peel may be the only frame to allow appreciation of, engine and frame and fork resonance with tire patch 10ish % slippage sonics which only half way over laps with the 'big bang' theory of power pulse spacing. Two cycle have surprised me on dusty gritty rocky lumpy loose dry surfaces to hook up hi throttle instead of spin > Peel Gravel hill climbs and Kelly George's flat tracker tire. Its very fun-educational to be able to feel the difference of wind buffet from forks and pilot legs and engine, road texture and tire patch adhesiveness grinding drag from the front engagement to back side release. Similar to sanding a tank with finer and finer grades of grit can go by feel of drag where it needs more or less smoothing out.
 
Re: Featherbed frame design went against all engineering pri

How many poeple have owned or ridden a 850 Commando as well as a 850 in a Wideline Featherbed, I brought my Commando new and 1980 coverted it to the Featherbed frame and built right will out handle the Commando, is a lot lot lighter than the Commando, as smooth to ride if the balance factor is right, I have been riding my 850 Featherbed for 34 years now, the last 5 years have put Lansdown fork kit in the front end, moden brakes and moden tyres and now it handles even better, mine you it handled pretty good before these upgrades, as well the Featherbed wheel base is shorter than a Commando wheel base, the motor sits as low as it can in the Featherbed frame and tilted the same as the Commando, the Featherbed feels so light when riding, very stable at high speeds and when it hits the twisties is when it comes into its own.
I have worked and rebuilt a few Commandos for mates that have got into them and have rode them as well, but I still perferr the Featherbed over the Commando and the Featherbed is so much fun to ride, it was my every day ride, except for times its was being worked on or having upgrades done to it and has done me well over all these years, I ride it hard all the time and has never had any cracks in the frame, but one very inportant thing with Featherbed frames is to have a strongly made head stay.

Ashley
 
Re: Featherbed frame design went against all engineering pri

Ashley wrote:

"......, but one very inportant thing with Featherbed frames is to have a strongly made head stay."

Agreed! Because the head stay is part of the frame!

All the negativity cited herein, regarding the elasticity of the curved tubes has failed to account for the fact that the engine side plates, engine, and head stay, make for a very strong triangular gusset sitting inside the loops, which taken in toto, makes the frame very rigid.

I am sure Dr Bauer recognized that isoelastics would effectively remove this gusset, which would THEN make the frame "springy", and thus he set out on a new design.

Slick
 
Re: Featherbed frame design went against all engineering pri

texasSlick said:
regarding the elasticity of the curved tubes has failed to account for the fact that the engine side plates, engine, and head stay, make for a very strong triangular gusset sitting inside the loops, which taken in toto, makes the frame very rigid.
Click to expand...

Thats not strictly true, when you study a featherbed closely ?

The engine/gearbox unit is really only attached to the front downtubes and above the rear swingarm,
and the top of the cylinder head is attached to the steering head with the head stay.
That actually gives the frame considerable scope to flex without influencing the power unit,
when you think about it ??

Now whether this was done deliberate or merely incidental is another matter entirely.
But the earlier Norton engines/gearboxes (pre featherbed) were attached to far more points on the frame.
And they had considerable troubles with those lugged frames breaking, at a number of possible places...
 
Re: Featherbed frame design went against all engineering pri

ashman said:
How many poeple have owned or ridden a 850 Commando as well as a 850 in a Wideline Featherbed, I brought my Commando new and 1980 coverted it to the Featherbed frame and built right will out handle the Commando, is a lot lot lighter than the Commando, as smooth to ride if the balance factor is right, I have been riding my 850 Featherbed for 34 years now, the last 5 years have put Lansdown fork kit in the front end, moden brakes and moden tyres and now it handles even better, mine you it handled pretty good before these upgrades, as well the Featherbed wheel base is shorter than a Commando wheel base, the motor sits as low as it can in the Featherbed frame and tilted the same as the Commando, the Featherbed feels so light when riding, very stable at high speeds and when it hits the twisties is when it comes into its own.
I have worked and rebuilt a few Commandos for mates that have got into them and have rode them as well, but I still perferr the Featherbed over the Commando and the Featherbed is so much fun to ride, it was my every day ride, except for times its was being worked on or having upgrades done to it and has done me well over all these years, I ride it hard all the time and has never had any cracks in the frame, but one very inportant thing with Featherbed frames is to have a strongly made head stay.

Ashley
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Do you ride it in slow traffic ? How did you get it to be OK both when ridden slow and fast ? My bike is very smooth, however I've usually got it revving hard. If it idles, it actually moves backwards and forwards because of the crank imbalance.
 
Re: Featherbed frame design went against all engineering pri

acotrel said:
If it idles, it actually moves backwards and forwards because of the crank imbalance.
Click to expand...

Or the torque reaction to the spinning crank.....
 
Re: Featherbed frame design went against all engineering pri

I ride my Featherbed everywhere, its not a stock motor with 2S cam, major head work and PWKs carbies, it idles good and works great with the Joe Hunt maggie, it will ride nice in top gear at 40 mph but under that have to drop it down a gear, I run stock Commando gearing, it will run great over the ton if need too and gets there pretty quick, when on the highway I cruise anywhere between 70 to 90 mph and it will sit on that speed all day without any problems, I have never had any problems with loosse exhaust pipes or anything falling off it in the 34 years its been built, I will be riding this bike till the day I die, its so good and the best thing is you won't see another one that looks like my bike and it was built by my own hands, if I need to do any major work on the motor I only have to undo 10 bolts and i can pull the motor, gearbox, primary and engine mounts out in one lift, so simple.

Ashley
 
Re: Featherbed frame design went against all engineering pri

Rohan said:
acotrel said:
If it idles, it actually moves backwards and forwards because of the crank imbalance.
Click to expand...

Or the torque reaction to the spinning crank.....
Click to expand...

Rohan, how can there be torque reaction when the motor is idling at constant speed out of gear? Surely to get torque reaction, there must be a load ?

About the head steady. With a manx frame it is often possible to change the steering characteristics by tensioning the the turnbuckle. I never used the turnbuckle, only a strip of steel between the lower lug and the head studs. It is not the way the frame should be used. At the time I did not appreciate the importance of the steering geometry as being so critical. In any case the steering was already stuffed when I fitted the 18 inch rims.
 
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