Real plans for a featherbed frame

motorson

motorson

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I'm planning to build a featherbed frame. I have some drawings downloaded but just don't feel like I have enough information to get started. Does anyone know where I can buy a set of real plans for a Norton Featherbed frame?

I'm getting more and more sure that I am going to put a V65 Sabre engine in one. I'll keep the shaft drive (the shaft that turns the bevel gear where the shaft is turns backwards if you were to try to put a chain drive on it.) It will loose a hundred pound from the stock Honda and have 120 horse power with no engine modification. Water cooling could be a big problem but hey, it will be a one of a kind bike.

Dan.
 
Just buy the tubing, and get bending......

Real plans for a featherbed frame
 
I know of several featherbed frame constructors locally, and a few more who were doing that previously.
As far as I am aware, all they did was find a frame, jig it up so it could be duplicated, and bend away...

As has been pointed out here and elsewhere previously though, there are over 20 versions of featherbeds, when you tot tham all up.
Manxes, dommies, singles, widelines, slimlines, Deluxes (with the bathtubs), a change every few years or so, etc etc.

One of the neatest was one for a Norvin, where the motor just slotted in and fitted. (Its usually a VERY tight squeeze.)
Capped by a Norton Interstate tank, unmodified.
Some careful thinking measuring cutting bending and welding there.
He was a big lad, so everything had been made to suit...
 
Thanks guys. Rohan, I realize that what it takes is to "start cutting metal." I like the idea of a stock interstate tank. The motor I have in my sights is going to fit rather easily in the space a featherbed has although I am thinking the forward cylinders may have to stick out between the down tubes. I may go a bit fatter on the tubing since I can do just about what ever I want if I am building every thing. Keeping the featherbed look and the retro-ness of the whole bike is a major part of the goal. I think that a lot of attempts lose their appeal because the front end just doesn't look right with a small wheel. There are other things as well that can ruin the Norton-café look. Any way, it will be fun and I'm sure a blast to ride.
Dan.
 
Ken Sprayson or Reynolds tubes MIGHT have one, but he is retired now and can only be contacted via his son.
In short you just need to get the dimensions of the engine and work to a drawing in ¼ scale, this will be far easier to correct any mistakes before you have cut any tubes.
 
Most after-market featherbed frames have been made by putting an original frame into the jig and copying. The modern Australian copies usually have Suzuki steering geometry so that 18 inch wheels can be used without stuffing the handling, which in any case is considerably different to the original and requires a different riding style. One thing which is very important when fitting different motors into the featherbed, is where the centre of gravity ends up. If the weight is too far back, the front end can be light and vague when you ride the bike, and the crash becomes easy.
From memory the original Featherbed had 24.5 degree steering head angle, the Suzuki type have 26 degree steering head angle and I don't know what offset they use on the fork yokes. You can get hurt playing with this.
 
acotrel said:
From memory the original Featherbed had 24.5 degree steering head angle, the Suzuki type have 26 degree steering head angle and I don't know what offset they use on the fork yokes. You can get hurt playing with this.
Click to expand...

We have seen your memory at work before - and where did you get that bit about the Suzuki steering angle. ???
Previous discussions here, remember ?, while throwing up a few different quoted angles, suggested the featherbeds WERE 26 degrees anyway.
One source has quoted that all featherbeds were 26 degrees, and lately a few have claimed 24 degrees for the slimline.
But there seems no visible difference when you eyeball them, or measure them...
 
Thers a real old drawing ( likely a proper one ) of a F'bed 9 filhed from the N.o.c. club / ) site here . You MIGHT find searching the
Featherbed Chassis Posts . Rather than some computer nerds interpretation of creation .
 
The 'wideline' drawing that was on the NOC turned out to be a slimline.
Even the nerds could spot that, so reality takes a back seat sometimes...

The steering head angle was indecipherable too, which was somewhat of a letdown.
It was said it was 24, 26 or even 28 degrees, depending on who is doing the saying.
(Mebbe the blurring waz deliberate ?).

Your 'here' doesn't point anywhere... ?
 
I have a cheap magnetic base protractor which can be attached to the fork leg. If you take one of those to a race meeting as well as a vernier caliper, you can measure the geometry of the better handling bikes. Most of the guys won't object, if you ask them nicely. Depends on what you want to use the frame for (application, wheel size and type of motor).
 
Watch that if you measure the fork legs in a stock Commando, they point a little backwards compared to the steering head.
This can be the source of considerable error, etc
 
acotrel said:
I have a cheap magnetic base protractor which can be attached to the fork leg. If you take one of those to a race meeting as well as a vernier caliper, you can measure the geometry of the better handling bikes. Most of the guys won't object, if you ask them nicely. Depends on what you want to use the frame for (application, wheel size and type of motor).
Click to expand...

It goes without saying, that this will only work accurately if the bike is parked on its wheel s on level ground :!: 8)
 
Rohan, when the Australian historic guys started playing with featherbed frames in the 80s, they made some the with the steering geometry similar to the RG250 two stroke, and with the 18 inch wheels, that's what they handled like. No longer was there the big sweeping curve into the corner, it became flash up to it and tip in. I'm fairly certain the angle used was 26 degrees. If you were going to use 19 inch wheels a steeper rake might be better. In the end it make a difference to how the bike feels when you ride it hard. An original manx inspires confidence because it usually tightens it's line in corners. The shape of the tyres also has an effect, triangulars became popular in the 50s for a reason. It's all very subtle effect, however if you are racing, can be the difference between winning and losing. Personally I hate bikes that feel light and vague in the front in corners.
If I was going to make a featherbed these days, I'd talk to someone such as Andy Molnar and try to find out what's the go.
 
acotrel said:
I'm fairly certain the angle used was 26 degrees.
Click to expand...

Odd that - thats whats stated as traditional featherbed steering angle anyway....

That makes featherbed 26 degrees, 750 Commando 27 and 850 Commando 28 degrees.
??
 
The drawing Mr Sprayson supplied me with many years ago has the head angle with respect to the bottom frame tubes at 26 degrees.
A Norton / AMC drawn drawing marked 1961 for the Domirace frame has it at 25 degrees. The drawing also included a different top tube variant which could of been for a Manx motor??????
Personally I was under the impression that the original Domirace frames were manufactured by Mr Sprayson to a sketch. The drawing being marked 1961 must have been drawn by AMC after the frames were manufactured and it showed a cross tube behind the gearbox that had it been positioned as per the drawing would of been cut through by the rear chain !! Comparing it to an original Domirace frame once borrowed photographed and played at drawing up (that had sat on a damp earth floor for decades and was basically scrap} showed the cross tube to be somewhat higher than shown on the drawing so I wonder what else was wrong with thedrawing........
There seem to be rather a lot of people attempting to make Featherbed frames these days...one friend borrowed a Dommy and ES2 frame from me not long ago for someone in the Midlands who is thinking of joining the game....... My frame making friend keeps busy at times repairing frames that have failed due to incorrect tube..incorrect welding .. general incompetence. I have even seen Norton frames where the cross tube between the top tubes behind the head stock is welded to the front down tubes.....clever idea is that if you want the down tubes to fail.....
One story I heard was that at one time an exspurt told the Norton race team manager (Mr Craig) that he should be nickel bronze brazing his Manx frames so he instructed Reynold to do so for the following years race team frames.....which all failed during the season! I guess Reynold knew just a bit about tubular frame construction (having done it for many years!!) which is why they employed Sif bronze No1 welding for the frames. Apparently Reynold simply followed instructions given by customers and ONLY gave advice IF asked for it s.....and I bet someone pointed this out to Mr Craig because later frames were Sif bronze No 1 welded!! Just a story I heard a while ago from a rather well informed source!
A few years ago a friend spent a day at Mallory park, having borrowed a LOT of test gear from a certain establishment, trying to determine why a new Manx frame had failed after only a couple of meetings and had failed in a place no Reynold frame ever failed at. I had suggested wrong tube bending or wrong welding or simply too thin tube being employed..Manx frames being 16 gauge 531...apart from I believe three 18 guage versions made for Francis Beart probably for his 350 Manx lumps but I believe it was suggested that they be cut up after a couple of seasons racing simply on safety grounds. Mr Beast's bikes always looked beautiful..........as a boy before I learnt just a bit about clutches and the effects of oil I often wondered how his bikes did the TT with so few friction plates ..... I very much suspect Mr Beart knew how to calculate clutch torque capacities......
Just had a look at the Renold drawing for a 500/650 engined frame...the head angle is 27 degrees. Was this the frame with a Triumph engine used by Percy Tait at one time I wonder? Another Renold frame drawing marked 'SPECIAL M/C FRAME A65' shows it at 26 degrees.
 
Much to reply to there.
That nickel bronze story sounds suspect, Reynolds had been welding up all Nortons featherbed frames since day 1.
It was also routine practice to change the clutch between practice and race, for many years.
It is stated elsewhere that 350 frames were all lighter gauge ?
What does this 27 degrees 500/650 frame look like, any pics ?
 
The tale about Mr Craig telling Reynold to use nickel bronze for sticking together one years Manx race frames rather than Sif Bronze No 1 was told to me by Mr Sprayson...........
 
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