Featherbed frame design went against all engineering princip

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Re: Featherbed frame design went against all engineering pri

Fast Eddie said:
But I am pretty certain it won't be on Youtube... !
Rohan said:
+1 !!!!!
Thats the funniest comment here for ages....
acotrel said:
Have you had a look at the MotoGP Workshop videos on Youtube ?

Did you hear about the 'engineer' who learned all his knowledge off Youtube ?
Only he didn't know about the invention of writing, or mathematics, or that folks needed to eat or sleep.....
 
Re: Featherbed frame design went against all engineering pri

Acotrel I have said this many times here and i will say it again for your benifit, my 850 Featherbed rides very smoothly on the road, the motor was build for the Featherbed frame, I can sit on 40 mph in top gear all day around town, but it does ride even better above that speed, but under 40 it will need to be put in 3rd gear, but very rare that I sit under 40 and any Commando will straggle to sit under 40 in top gear, so have you ridden a 850 Featherbed on the road before, as you keep telling us you never ride on the road so how can you come up with these claims, I built my motor around a stage 2 in the performance section of my old work shop manual with the 2S cam with head work to match as well as a few other things, but I also got the crank balanced at 72%, if I wanted to race my Norton on the track I would have built it as a stage 3 which is also in my perforance section of my old workshop manual, but it would be no good for road use, but that was in 1980 when I built this Featherbed, there are so many new perforance parts these days compared to what was around when I built my bike as well as the internet which was only a dream at that time.

There was no UTUBE in them days.

Ashley
 
Re: Featherbed frame design went against all engineering pri

Triton Thrasher said:
acotrel said:
'a Seeley frame is obviously superior because of the tubes which run from the steering head to the pivot, and the construction around the pivot.

The Seeley frame looks to have more rigidity in the relationship between the swing arm and the steering head.

It's probably better than the Featherbed frame in some situations. Taking my 42 bhp roadgoing engine out of its Wideline and putting it into a Seeley is not likely to show an improvement that I can discern.

Putting a 900cc Jap racing four into a Featherbed frame is probably a silly mistake.

The steering geometry of the Seeley is different to a featherbed. With the manx engine fitted and 19 inch wheels , the featherbed slightly tightens it's line and feels positive and confidence inspiring. It you get off-line you usually simply give it more stick. The way my Seeley is set up, it tightens it's line that much that you need to anticipate where you will be coming out of corners, well before you get there. It means you can get the power on a lot earlier. I feel very confident when riding it, however it is probably going to bite me. I'd much rather ride a Seeley framed bike than a featherbed, unless the latter had the manx engine fitted. I believe the 1962 manx was an old style bike which had the most rider input contributing to it's development. I don't believe a manx engine in a Seeley frame would be better. I suggest a 1000cc CR five speed Harley Sportster motor in a Mk3 Seeley frame would not be all bad.
 
Re: Featherbed frame design went against all engineering pri

ashman said:
Acotrel I have said this many times here and i will say it again for your benifit, my 850 Featherbed rides very smoothly on the road, the motor was build for the Featherbed frame, I can sit on 40 mph in top gear all day around town, but it does ride even better above that speed, but under 40 it will need to be put in 3rd gear, but very rare that I sit under 40 and any Commando will straggle to sit under 40 in top gear, so have you ridden a 850 Featherbed on the road before, as you keep telling us you never ride on the road so how can you come up with these claims, I built my motor around a stage 2 in the performance section of my old work shop manual with the 2S cam with head work to match as well as a few other things, but I also got the crank balanced at 72%, if I wanted to race my Norton on the track I would have built it as a stage 3 which is also in my perforance section of my old workshop manual, but it would be no good for road use, but that was in 1980 when I built this Featherbed, there are so many new perforance parts these days compared to what was around when I built my bike as well as the internet which was only a dream at that time.

There was no UTUBE in them days.

Ashley
Ashley, I believe what you are saying is true, however the Atlas had to compete with the CB750 Honda for smoothness and Norton probably became paranoid. My Seeley is balanced to 72% and above 3000 RPM it is super smooth right up to the 7000 RPM rev limit, below 2000 RPM it is a horror. (I probably use higher overall gearing than you do). It would be really unpleasant trickling through traffic with it. You don't need that much adrenalin and it is not for novices. I really like the way it is so precise, direct and quick - suits the way I race, however it is not for public roads. I think I'd be certain to bounce it off a car in short order if I tried that. A featherbed bike might be a bit nicer.
A few years ago when I first came to Benalla I had an RD250LC on the road. I found that on the main roads when trying to ride in a straight line it was steering itself from the slight ridge the trucks leave in the bitumen. I've been spoilt by riding on race tracks, however I cannot ever remember having those sorts of problems when I rode Triumphs as a kid. In those days you could get away with fanging the bike, so a hot motor was never a problem - late 50s, early 60s in Australia - I started racing in 1967.
 
Re: Featherbed frame design went against all engineering pri

I have rode a few 750 Atlas and I don't like them, not very smooth at all compared to my 850, I can't wait to get my 650 Manxman on the road as it was built for the track and the crank has been ballanced, I don't know if you know him but its a ex Mike Farrel bike, I brought it from a mate of my brother in law who brought it from Mike over 18 years ago, he pulled it all apart and never put it together again so it was just parts when I got it with a missing head.

Ashley
 
Re: Featherbed frame design went against all engineering pri

ashman said:
I have rode a few 750 Atlas and I don't like them, not very smooth at all compared to my 850, I can't wait to get my 650 Manxman on the road as it was built for the track and the crank has been ballanced, I don't know if you know him but its a ex Mike Farrel bike, I brought it from a mate of my brother in law who brought it from Mike over 18 years ago, he pulled it all apart and never put it together again so it was just parts when I got it with a missing head.

Ashley
Are you referring to the Mike Farrell up in Queensland who makes the oil pumps for the Jawa speedway motors used in historic racing ? I think I've seem him racing in Victoria at the championships.
I would love to own a Manxman, they were probably the best 650cc twin in their day. Not many were sold in Australia, and I think they were expensive. A friend had one and it seemed to be at least as fast as a Bonneville, and didn't have the rattles and leaks.
 
Re: Featherbed frame design went against all engineering pri

ashman said:
I have rode a few 750 Atlas and I don't like them, not very smooth at all compared to my 850,

You keep telling us its the balance factor of your 850-in-featherbed that makes the difference.
Presumeably an Atlas with a similar balance and engine setup would be similarly smooth ?
 
Re: Featherbed frame design went against all engineering pri

Yes Rohan they probly would be but the ones I rode were just stock, but I still enjoyed riding them, any chance to ride any Norton is all good.
Acotrel that is the same Mike Ferrell, I have never met him, I have his phone number and address so one day will get to meet up with him, he lives not to far from me, I have seen him at a few swap meets but didn't realise it was him at the time, he runs his business from his home, it be intresting to know the history of my Manxman, is wasn't stock but still had the blue frame and motor parts, but the motor and frame numbers don't match, the motor is out by 65 in the numbers, its not a SS motor but it has some interestting things in side it, I wish I had the original head for it.

Ashley
 
Re: Featherbed frame design went against all engineering pri

Rohan said:
ashman said:
I have rode a few 750 Atlas and I don't like them, not very smooth at all compared to my 850,

You keep telling us its the balance factor of your 850-in-featherbed that makes the difference.
Presumeably an Atlas with a similar balance and engine setup would be similarly smooth ?

I agree, Ashman's comments don't make sense. Prepare a 750 engine to the same standard as an 850 (828?) and there will be less vibration due to the reduction in reciprocating weight.

Whilst I'm chipping in, the comment allegedly made by Dr Bauer and posted on Wikipedia has no point of reference. I'm not saying he didn't make the comment just don't assume everything on the net or in a book is factually correct. The author also mentions "superblend" bearings (they don't exist), the rear chain adjusting bolts "pushing"? the rear axle (tightening the rear axle to the correct torque should help) and crankshaft bearing failure due to galling caused by high engine rpm. The actual limiting speed for these bearings is in the region of 12,000rpm ref. FAG catalogue 41 510 EB.

Tony Foale, another advocate of the spine frame, reckons the featherbed is an inefficient design i.e not much stiffness for the weight, http://www.tonyfoale.com/ Click on 'Articles' and scroll down to 'Practical' and click on 'Frame Stiffening',

Jose.
 
Re: Featherbed frame design went against all engineering pri

I'm not entirely sure I agree with this post ?!

850's would have more reciprocating weight than a 750, the pistons were heavier.
Talking all stock oem components here, which engines may or may not be some 40+ years down the track...

While 'superblends' may not exist as such, heavier duty bearings do exist,
and were needed to solve the Combat 750's notoriously short main bearing life.
I'm not sure that galling was the problem, or what the actual wear problem was that caused the problem,
but pre 'superblend' they sure didn't need to get to 12,000 rpm to have problems....
 
Re: Featherbed frame design went against all engineering pri

Rohan said:
I'm not entirely sure I agree with this post ?!

850's would have more reciprocating weight than a 750, the pistons were heavier.

That's what I said.

[quote="Rohan"
While 'superblends' may not exist as such, heavier duty bearings do exist,
and were needed to solve the Combat 750's notoriously short main bearing life.
I'm not sure that galling was the problem, or what the actual wear problem was that caused the problem,
but pre 'superblend' they sure didn't need to get to 12,000 rpm to have problems....[/quote]

That's my point, they fitted bearings suitable for the job. I guess the previous unsuitable bearings got fitted because they were cheaper,

Jose.
 
Re: Featherbed frame design went against all engineering pri

Jose Refit said:
"superblend" bearings (they don't exist)

"Superblend" was a designation apparently applied to the R&M/RHP 6/MRJA30 bearing by the factory (or R&M?) so they do 'exist'.


FACTORY SERVICE RELEASE N.2/19

NATURE OF RELEASE: Crankshaft main (roller) bearings

MODELS AFFECTED: 1972 Commando (all models)

DISTRIBUTION: Worldwide (Distributors and Dealers)

EXPLANATION: In order to extend main bearing life, a change of roller main bearing specification has now been authorized, and fitted on production engines from engine number 211891.

The new roller bearing is designated "SUPERBLEND" with an increased load carrying capacity and are supplied under part number 063906 (manufacturer's part number R&M 6/MRJA30).
 
Re: Featherbed frame design went against all engineering pri

Makes a difference whether 'Superblend' was coined by the factory or by R&M though ??

Marketing speak is no guarantee of authenticity of terminology .... ?
 
Re: Featherbed frame design went against all engineering pri

Jose Refit said:
I agree, Ashman's comments don't make sense. Prepare a 750 engine to the same standard as an 850 (828?) and there will be less vibration due to the reduction in reciprocating weight.

This statement is written ambiguously then.....

If 'a 750 was prepared to the same standard as an 850',
then you'd have to fit heavier pistons to a 750 ??
 
Re: Featherbed frame design went against all engineering pri

Jose Refit said:
That's my point, they fitted bearings suitable for the job. I guess the previous unsuitable bearings got fitted because they were cheaper,

The Combats explored performance levels - and bearing loadings - beyond previous Norton engines.
Presumeably this caught the reliability folks by surprise, since main bearings in Atlas's didn't have these problems (?).
So they fitted what they'd previously fitted, and only later found out they weren't up to the job.

So that 'fitted because they were cheaper' jab is not correct ?

And it cost them a small fortune remedying these problems...
 
Re: Featherbed frame design went against all engineering pri

I don't know why superblend bearings were better than the earlier type, I bought mine purely on advisement. I do know this though, I seen a few sets of repaired crankcases which have failed on commando motors which have had the tits revved off them. My feeling is that revving a motor with a balance factor which does not give smooth running at the rev limit, is asking for trouble. From all that I've read and seen about commandos, I believe that 7000 RPM is about as far as it goes, and after that the law of diminishing returns applies. Everything that I've done to the motor on my bike has been about fattening up the midrange and raising the overall gearing as it improves. Would you expect a bike to accelerate faster when you raise the gearing ? It is very deceptive even when you short-shift.
 
Re: Featherbed frame design went against all engineering pri

Rohan said:
Makes a difference whether 'Superblend' was coined by the factory or by R&M though ??

Marketing speak is no guarantee of authenticity of terminology .... ?

As far as we know it was a name given to a particular type of bearing as used by the Norton factory. Whether the term was known outside Norton or used by bearing manufacturers is debatable, so authenticity would seem to have little to do with it.
 
Re: Featherbed frame design went against all engineering pri

If the bearing manufacturers have never heard of that term,
and it was invented by the marketing dept,
then that would appear to have some bearing on the matter !!
haw haw haw, pun intended...
 
Re: Featherbed frame design went against all engineering pri

acotrel said:
I seen a few sets of repaired crankcases which have failed on commando motors which have had the tits revved off them. My feeling is that revving a motor with a balance factor which does not give smooth running at the rev limit, is asking for trouble.

You keep saying 'you have this feeling'.
But there is no engineering justification to say that balance factor alone is responsible for this. ?
Plenty of crankcases back in the good ole days could split in half.
Weak castings and/or lubrication failure is often attributed to these.
Manx Nartons were famous for splitting their timing side case in half.
Thickening up the casting around the bearing in modern replica castings has almost entirely eliminated this failure.
So maybe they simply weren't strong enough to begin with ??

acotrel said:
From all that I've read and seen about commandos, I believe that 7000 RPM is about as far as it goes, and after that the law of diminishing returns applies.

This is hardly surprising, nor a revelation - the tacho has the red line marked as 7000 rpm !!!,
and the makers say the piston accel/deccel forces beyond this rpm is dangerous.
 
Re: Featherbed frame design went against all engineering pri

Rohan said:
Jose Refit said:
I agree, Ashman's comments don't make sense. Prepare a 750 engine to the same standard as an 850 (828?) and there will be less vibration due to the reduction in reciprocating weight.

This statement is written ambiguously then.....

If 'a 750 was prepared to the same standard as an 850',
then you'd have to fit heavier pistons to a 750 ??

Yes, you're right, Rohan. How could I have been so stupid. Thanks for putting me right. I'll bare this in mind on the next rebuild of my MZ250 - which I'm going to do to the same standard as the Norton - though does this mean I have to put valves in the cylinder head? - obviously I'll make the piston heavier,

Yours, losing the will to live, Jose.
 
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