Where is info on Isolastic Featherbeds?

jimbo

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I have 1959 Wideline and I'm considering rubber mounting, where is there any information, I know many have done it.
 
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Maybe they didn't work, I have my 850 solid mounted in my Wideline for 33 years now, with the crank balanced for the Featherbed frame and I have no problems with vibrations at all, Featherbed frames were made for solid mounts and putting a rubber mounted motor in a Featherbed will change the way they handle, but mind you this is only my opinion, there would need to be a lot of modifrcations to the mountings on the Featherbed, a lot of expermenting, a lot of time and money and it mite not work, a lot cheaper and less headaces to just get your crank balanced right for the Featherbed frame, mine was done at 72% balance factor.

In 33 years I have only had one bolt come lose where I lost the nut so I must have done something right and at the time it only cost me $46 to get the crank balanced, I don't know how much it would cost these days but would be a lot cheaper than experamenting with rubber mounts that might not workout.

Good luck with it but I would never go back to Isolastics and my Featherbed 850 handles so well, but it all depends on how it is set up.

Ashley
 

ntst8

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Have you tried a search for "featherlastic" either on this forum on the the net in general?
A few useful links should pop up.
 

jimbo

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ntst8 said:
Have you tried a search for "featherlastic" either on this forum on the the net in general?
A few useful links should pop up.
good job :) , I forgot about "Featherlastic"
 
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Just a personal whinge , but the powertrains a integral part of the frame , structurally . Take Note .

Reading the Thing on the pre war BSA Sloper Today - the ANGLE gets the thing SMOOTHER , amougst other things .

The Commando set up , angled - in the F'bed , may well be smooth enough .
 
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Search also for "Bob Fraturelli" on the web. Should return links to how he built his Featherlastics.
 
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Matt Spencer said:
Just a personal whinge , but the powertrains a integral part of the frame , structurally . Take Note .
Of more concern even is that on the stock featherbed, the top of the steering head is braced as part of the engine steady, to the top of the cylinder head/rockerbox.

When you see it all bare under the tank there, on a stock bike, it is apparent that its an integral part of the frame's and steering head's strength.
Once the powertrain is isolastically mounted, what happens to that bracing to the top of the steering column ??
Unless some other bracing system is adopted in the featherlastic, that bracing has been lost.
That CANNOT be a good thing ?

Is there something that is not being revealed that is done to featherlastics in this dept ?
Or are we talking emperors new clothes....
 

jimbo

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legend has it,they used to leave the brace off to let the engine move, with better 1/4 mile times
 

jimbo

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you mean this piece of steel with one hole going to the head?


Rohan said:
Matt Spencer said:
Just a personal whinge , but the powertrains a integral part of the frame , structurally . Take Note .
Of more concern even is that on the stock featherbed, the top of the steering head is braced as part of the engine steady, to the top of the cylinder head/rockerbox.

When you see it all bare under the tank there, on a stock bike, it is apparent that its an integral part of the frame's and steering head's strength.
Once the powertrain is isolastically mounted, what happens to that bracing to the top of the steering column ??
Unless some other bracing system is adopted in the featherlastic, that bracing has been lost.
That CANNOT be a good thing ?

Is there something that is not being revealed that is done to featherlastics in this dept ?
Or are we talking emperors new clothes....
 
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When I frist started to build my 850 Featherbed, one thing that I was told was to make the top mount from the steering head to the top of the cylinder head was to make it as strong as can be with no movement at all, if you ran the Featherbed frame without a strong head stay the frame would crack at the top of the frame near the steering head, my friend who got me into Featherbed frames learn the hard way of not having a head steady on his first build and his cracked servely, so can not have any movement at all is the best way.

Ashley
 
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You can look at a featherbed frame and a commando frame and believe they do the same thing - not so. I suggest he featherbed is a much better option if you want precise handling. With a rigidly mounted motor the balance factor is more critical. If you get it to shake at low revs and smooth out in the usual operating rev range that would be good. I'd never run a featherbed without a head steady, even with one they can crack at the front engine mounts. With a featherbed, even the type of bush used in the swing arm makes a difference you can feel. A lot of road bikes used to have silentbloc bushes which we used to change for solid brass bushes. Isolastics on a featherbed might be OK on a road bike with modern tyres, if you are insensitive. I would not do it.
 
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The old gent that balanced my crank for the Featherbed was a Englist engneer who made racing frames for fomular 3 race cars and I was put onto him from Ivan Thighe of Thighe Cams in Brisbane who built my stock cam up to a SS profile and he had a lot of his race engines balaced by this gent, when I told him what my plans where with the 850 in the Wideline Featherbed he told my what balance factor I needed and what he needed to balace the crank.

What ever he did my motor is smooth right through the rev range and has been for over 33 years.

I don't understand why poeple are so obsess with Isolastics, if you build your motor for the Featherbed there is no need for them, the best thing I ever done was to build my Featherbed as they will handle a lot better than a Commando and I built mine long before the internet was around, I was young when I built it and not much experance with building a bike from the ground up, but one thing I did do is use comand sence.

Ashley
 
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The factory sure didn't make any Featherbeds with Isolastics. The engine suspension system was unique to the Commando.. The F/B was out of production before the isolastic system was released. Any "Isolastic Featherbed " is a bitsa.

The prime driving force behind the isolastic system was the horrible vibration level of the Atlas. We reckoned that a headlamp bulb would fail a 5000 iles even if it was never turned on. The vibration shook the filament off its posts.

200 miles on one of those suckers and your hands and feet were numb! The P-11 was tha same - I put a lot of miles on a P-11 prorotype. Vibration was manageable on the 500 and 600 Dommies, marginally acceptable on the 650SS, but the Atlas was awful.

I don't think the F/B frame could be adapted to isolastics. It's structurally so different.
 
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Frank, google on 'featherlastic'
Those folks in Tucson have built quite a few of them - they were all the rage at one stage.
Even have their own website http://www.featherlastic.com/
They even show an undertank view of the headsteady - but how that works with a flexy engine is anyones guess ?
Quite a smart looking special.

BTW, you seem to have forgotten about the Mercury. ?
This was essentially a single carb blue 650SS in a featherbed frame, built and sold at the same time as the 1969 and thereabouts Commandos....
 
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Yes they do look good and these poeple have gone to a lot of troubles making a product that they hope to sell, I still would like to ride one to see if they do handle well, some poeple would ride them but have never experanced riding a Featherbed frame bike before and would say they handle well, but put someone on the bike that has many months of riding a true Featherbed frame and see how they realy handle, you just can't hop on a Featherbed and ride it without getting use to them first.

When I first rode my 850 Featherbed my mate was on his Commando and telling me to push it throught the corners hard, was easy to say but in real life you need to ride it and get use to the way it rides and handle, but after a few weeks of riding it , it just got better and the more I rode it the more I pushed it and the more I loved it, you need to learn to slow the bike before the corners then while in the corners just open it up and let the Featherbed do its job, I push mine very hard and just love tight mountain roads with a few long, fast straights to wind up my hot motor, my 850 has a lot of power and is perfect in the Featherbed frame, it is a lot lighter and has brakes and suspenstion that work well, I also push my tyres to the edge of their limits, you need good rubber.

This is only my throughts, but I still reacon a Isolastic Featherbed will not handle as well as a trues Featherbed with hard mount engines, they are just changing the complete bike and I think I have the experance to know as I have been riding my 850 Featherbed for over 33 years now and it was a everday ride till last year when I brought my new Thruxton.

Ashley
 
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I've seen a period 3 historic race bike which was a featherbed 850. It gets passed off as a 750cc Atlas, however I believe it would be an excellent race bike - it would scare the shit out of the Triumph riding opposition. The Commando engine would be better than the 650 engines in that frame, the forward leaning motor would help the weight distribution, so the handling would inspire more confidence.
I have a problem with historic race rules which inhibit building such bikes. I feel we should be able to pursue the development of that basic technology
 
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ashman said:
built my stock cam up to a SS profile
This is where the story gets a little murky, Ashley. ?
The stock cam in a Commando IS the SS cam profile from the earlier dommies...

??

P.S. Featherlastics were a (passing) fad ??
 
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