NTNOA Info-Library


The Origin of the Famous Norton Featherbed Frame
Hope for Norton Fiberglass Fuel Tanks
Witworth or Withworthless
A Sidecar Primer
The Best of the Best in Texas

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The Origin of the Famous Norton Featherbed Frame

The Norton featherbed frame was created around an old fashioned long stroke single cylinder engine with a very top heavy cylinder head. The size of this engine dictated the space between the top and bottom rails of the full duplex cradle. In retrospect the result of this early effort enabled all kinds of engines using all kinds of configurations to be installed ion to this versatile and robust frame. Originally, it came with a bolt on rear sub frame which eventually got welded up particularly when the bolts came loose. Over time there where 3 major versions of the frame. These 3 major groups came in the bolted and welded variety.

a. The Manx racer in Reynolds 531 chrome moly.

b. The single overhead cam International in grade A mild steel.

c. The Dominator twin frames in grade B mild steel.

Then there where 2 subdivisions in category a. 16 gauge tube for the 500cc and the 17 gauge tube for the 350cc. Tube gauge is important so don't go putting a 500 in a 350 frame.

Then in category c.. in about 1959 or 1960, Norton put the old single cylinder Model 50 (350cc) and the ES2 (EaSy2, 500cc) into the featherbed to rationalize frame production. As you can see there where quite a few variations on what looked to be the same frame. Intact they came off the same jig. 1960 was the year the top rails where installed at the rear of the tank. This wasn’t just an Atlas mod, it was across the board. At the same time the tank design and its badges where changed.

Edited from the Internet

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Tanks For the Memories or Hope For Norton Fiberglass Fuel Tanks

There are three main requirements for a successful sealing job:

1. The most important requirement for sealing a fiberglass tank is to start with a solid tank. If there are any soft spots they must be removed and replaced with new fiberglass. If you're not into high-speed grinders and polyester resins then you're better off chucking the tank and looking for something better to start with.

2. The second requirement is that the inside of the tank must be extremely clean. Everyone has a different process for cleaning the following is know to work.

3. The third requirement is that the sealer used must be compatible with the fuel types to be used in the tank. Not all tank sealers are compatible with fuels containing non oil-based compounds. Specifically, some sealers can be dissolved by very small amounts of alcohol such as is added to gasoline during the winter. (These are commonly called oxygenated gasoline.) Some products such as 3M's 776 sealer appear to be a good industrial-grade solution to the problem however, upon closer examination, the main solvents listed are all alcohol. 3M's technical assistance people say that small amounts of alcohol turn the 776 sealer into a big gummy ball.

One important point to remember about any product sold as a tank sealer is that they do not cure to a hard state. You could use a polyester resin to slosh inside the tank and in effect build up a gelcoat layer inside the tank but this would dry to a brittle hardness and could crack if the tank flexes. Consequently most tank sealers air dry to a vinyl-like plastic coating.

There is a product recommended by the marine and aircraft people called Randolph Products 912 Alcohol Resistant Sloshing Sealer. This is available from aircraft repair places. Cost is reasonable and is a good sticky industrial product full of all you favorite aromatic carcinogenic solvents: MEK, toluene, cyclohexanone and xylene. (needless to say that you might not want to use this in the house)

The application procedure recommended follows:

1. Drain tank and remove cap and petcocks.

2. Rinse several times with hot water and dish detergent. Throw in a handful of pea gravel with a little soapy water and shake the tank well so that the gravel scours all the internal surfaces and loosens up any residues. Rinse several times until all the soap is out of the tank.

3. Seal the tank drain holes with small cork stoppers and pour in a quart or so of white gas (Coleman stove fuel) Slosh this around and let it sit for 30 minutes to remove any fuel dyes in the tank. Drain and let the tank air dry for at least 30 minutes.

4. Pour approximately 1 quart of MEK into the tank and slosh it around. Seal the tank and let it sit for one to two hours. Put a handful of clean pea gravel in again and shake vigorously. If the tank has been sealed previously, the MEK should soften any remaining sealer and the gravel should loosen it. Drain the tank.

5. Remove the gravel. If it has loosened any crud, pour in more clean MEK and gravel until no more residue comes out.

6. Make certain that all bits of gravel are removed from the tank. You may have to reach in the filler hole and pull out the last few pieces with your fingers. If your fingers are not small enough, you can shake the remaining gravel over to the filler hole side and use a vacuum cleaner with a crevice attachment to suck up the last bits. (Don't do this while there are still flammable vapors in the tank .)

7. If there are still little bits of crusties coming out, keep flushing the tank with MEK or acetone until the liquid comes out clear.

8. In between filling the tank with the solvents flush it with lots of hot water. It's cheaper than MEK or acetone.

9. Finally, after the last rinse and when the inside of the tank is dry, plug the petcock holes with clean cork stoppers.

10. Pour in the quart of sealer and seal the filler hole by laying a piece of plastic across the opening and closing the cap on top of it (a plastic sandwich bag of the heavier kind works here). If you don't want to ruin your paint, make absolutely certain that you have the tank well sealed since it will build up pressure as you slosh the sealer.

11. Shake and rotate the tank so that the sealer coats all internal surfaces and then drain the excess into a proper bucket. Pour the excess back into the can since it can be reused.

12. Allow the tank to drain and dry with the corks removed for 30 minutes or so.

13. Repeat the sloshing process (steps 10 - 12) and let the tank dry with all openings uncovered for at least 24 hours - longer if the temperature is less than 70 degrees. The instructions on the sealer only say to use two coats, however if the internal surfaces are very rough do it about 4 times. Let the tank dry for a couple of weeks.

14. When you a confident that all the sealer has dried, clean the excess from the threads in the drain holes with a small wire bottle brush or whatever else is handy, put the petcocks back in using some Teflon pipe thread compound on the threads as a backup to the paper gaskets, put the tank back on the bike and GO!

Edited from the Internet

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Whitworth or Withworthless

Ever wonder why the fractional sizes stamped on your Whitworth wrenches don’t match the size of an ordinary (US) spanner? Why use a fine vs. coarse thread? Read on. This is more than you probably ever wanted to know. But hey, this is the age of information glut.

By Professor Charles Falco

In the 19th Century every British factory which needed to bolt something to something else devised their own fasteners to do it. Clearly, this caused all sorts of compatibility problems. So, along came Mr. Whitworth (I forget his first name right now) who invented a standardized system of coarse threads (with 55 degree thread angle and rounded roots and crests). This standardization was a Good Thing. Along with his threads came heads for the bolts that were based on the length along the side of one flat, rather than across the flats. Hence, there is no simple fractional number for the length across the flats, which is why your American wrenches don't fit. The fractional number on your English wrenches refers to the diameter of the bolt (which is 1/4", 3/8" etc. just like in the U.S.); not to the distance across the flats (which ends up being various weird dimensions).

Some years later the Brits decided they needed a finer pitch for some applications, so another thread series was introduced (same 55 degrees). They also decided that the heads were too big for the bolts, so for most applications they switched to using the next size smaller heads. Because of this, and to add one more bit of confusion to life, one manufacturer will mark a particular wrench (spanner) BS 3/8, while a different manufacturer will mark the same sized wrench W 7/16. They fit the same diameter bolt.

The first thing any fledgling Brit biker learns is that his motorcycle has "Whitworth bolts." They think this is interesting, buy a set of Whitworth wrenches, discover these wrenches fit their bolts, and believe they now know everything they need to know about British fasteners. Unfortunately, at this point they know only enough to make themselves dangerous. Instead, what they should have said to themselves is Ohmygod, what other weird and incomprehensible things have the Brits done to the fasteners on my machine? The answer to this question is: British Standard Whitworth (BSW)

Sir Joseph Whitworth proposed this thread in 1841.
p = pitch of the thread
d = depth of the thread
                                       r = radius at the top and bottom of the threads
    d = 0.640327 p
    r = 0.137329 p

These are the original, 19th Century, coarse-threaded industrial bolts designed to hold locomotives together. Because of their coarse pitch, they are more prone to vibrating loose, so are little used on motorcycles. Except for threading into Aluminum (e.g. crankcase studs), where a coarse thread is less prone to stripping than a fine one. It turns out that, except for 1/2" (where the Brits use 12 tpi, and the Americans 13 tpi) the thread pitches are the same as for American Unified Coarse (UNC). However, the thread form is different; Whitworth = 55 degrees; UNC = 60 degrees. In spite of this, mismatched nuts and bolts mate nicely, so you're likely to find UNC bolts or studs where BSW should have been.

British Standard Fine (BSF)

A finer pitch series, analogous to the American Unified Fine (UNF), although (unlike the case of BSW/UNC) with none of the pitches in common with UNF. Many motorcycle manufacturers commonly used a lot of BSF threads.

CEI (Cycle Engineers' Institute) or BSC (British Standard Cycle)

These are different names commonly used for the same threads. 60 degree thread angle, rather than the 55 degree of BSW and BSF. For sizes from 1/4" through 1/2" by far the most common are 26 tpi, although 24 tpi appear as well. most but by no means all, fasteners on post-War BSA's (through the late '60's, when it got more complicated) were CEI. Although the thread form and pitch is different, the head sizes on CEI-threaded fasteners use the same wrenches as BSW/BSF.

British Association (BA)

47-1/2 degree thread angle. This is a metric thread system devised by the British for small screws used in components like speedos. Not metric like you might expect, but with diameters determined by a factor proportional to a power of the logarithm to the base 10 of the thread pitch in millimeters. I couldn't possibly be making this up. Ah, the English. You'll find lots of BA threads on any British bike, but only for fasteners smaller than 1/4". BA fasteners have their own set of wrench sizes. Typically, a set of Whitworth sockets will include a 0BA (and maybe a 2BA….bigger number = smaller size) socket.

British Standard Pipe (BSP)

A tapered, self-sealing thread system used to seal fluids (interestingly, the US and the metric world standardized on the BSP system for threading all their pipes).


In the late 1960's, when even the U.S. was thinking of going metric, the giant BSA corporation decided it was finally time to scrap that old 19th Century Whitworth-based system, and switch to....yes, you guessed it, American. Since they had lots of money invested in tooling, the switch wasn't made suddenly (or completely), so bikes from the late '60's and later had a mix of all sorts of thread forms. Typically, engine internals (e.g. the thread on the end of a camshaft) stayed with whatever form it used to have, while simple fasteners (e.g. holding the fenders on) switched to UNF.

None of the Above

While the above systems account for well over 95% of all threads you'll ever run across on a British bike, some manufacturers—again BSA springs to mind, but others were guilty as well--couldn't restrain themselves from inventing a few oddball pitches of their own. This is why, when dealing with British bikes, you should assume nothing. You must have a pitch gauge and calipers.

Reprinted from the Internet

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A Sidecar Primer

by Karl J.W. Brohan

For those of you who have ever fantasized about piloting a sidecar rig, here are a few pointers which I have arrived at through practical experience. The following discussion relates to cars mounted on the right side of the motorcycle.

Because the sidecar weight is not located over the Center of Gravity (CG) of the motorcycle there is a yaw reaction about the vertical axis in reaction to acceleration or deceleration forces.

Under acceleration the rig pulls right.

Under deceleration the rig pulls left.

These seemingly annoying characteristics can be used to enhance cornering capability.

Right Turns

When attacking a right turn:

Decelerate prior to curve entry.

At the apex of the curve, roll on throttle and the sidecar will pull to the right reducing pressure on the handlebars and the tendency of the car to roll around the longitudinal axis.


Entering a right hand curve with a great excess of speed will cause the sidecar to "fly" and attempt to roll counter-clockwise about the motorcycles longitudinal axis.


Attempting to apply moderate to heavy braking in a right hand curve will exacerbate the situation and the sidecar will continue to roll. An additional vector will attempt to throw the weight of the car over the front wheel. This dramatically increases steering effort and instability while the car is airborne. The rear wheel of the motorcycle will unload and there is a possibility of the front wheel slamming against the stop with highly unpleasant results. (A sidecar end!)


Best tactic for entering a right-hander too hot:

Try to stay to the inside of the corner so you have room to runout wide if necessary to keep car from going over the critical roll angle.

Use aggressive throttle after the curve apex and during turn exit. This will increase turn rate without increasing sidecar roll.

Left Turns

When attacking a left turn, enter the turn with trailing throttle and light front and rear brake. (For rigs with a sidecar brake linked to the rear brake pedal, use light front brake only.) The severity of the curve dictates the brake/throttle position. For example, a hard left turn: use no throttle and moderate front and rear brake.


Rolling on moderate or greater throttle after the apex of the curve, but prior to the curve exit, will cause the sidecar to attempt to pull the rig off the side of the road, possibly sliding the front wheel to the outside of the curve and into the rough!

Minimum Radius Turns

Minimum radius, slow speed turns are best accomplished with a right hand turn. The rig will almost pivot around the sidecar wheel with minimal steering effort required. (one to one and a half times width of the rig)

Minimum radius left hand turns are much more difficult for you and the rig. (three to four times width of rig) This is like trying to make a slow speed left hand turn in a heavy B-767 with the right engine shutdown!

Steering Head Wobble

Steering head wobble is normal to some extent in all sidecar rigs. This is most likely to manifest itself when riding at slower speeds over irregular road surfaces. Increase steering head bearing pressure or steering damper pressure (if installed). Usually these wobbles are momentary and do not warrant tightening the steering head bearing pressure or increasing steering damper pressure. However, if you will be riding over an irregular surface for an extended period, I would increase bearing or damper pressure. Be sure to relax pressure when the surface again smoothes out.

Note: for those of you wondering how to increase steering head bearing pressure on the fly, this is only possible on bikes with a handle on the steering head such as older BMW's.

Additional Operational Info and Tidbits

Flying the sidecar in right hand turns is great fun, but very hard on the rear wheel and spokes. Expect to have to tighten a rear spoke occasionally or to replace a broken spoke. Repeated showboating can crack the rim spoke nipples.

Things to get for the tool kit:

In addition to the normal tool kit and spares items, a small bottle jack is almost mandatory to change the sidecar wheel in the event of a flat. Extra spokes and tubes are also handy to have.

One final Warning: If the vehicle has been parked and not under continuous surveillance, check the sidecar wheel to ensure the knock-off hub (if installed) has not been loosened by some prankster.

As with any vehicle, treat a sidecar rig with proper respect and you will realize many happy miles of motoring in great style!

Karl J.W. Brohan

PS Beware, Volvo station wagons seem to be totally fascinated by the sight of a sidecar rig and have been known to stop in the middle of the road and gawk!!

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The Best of the Best in Texas

From seacoasts to mile-high mountains, Texas offers a little bit of everything including roads you'd swear were built specifically for motorcyclists. Here's the top 10, courtesy of Todd Nunnally and the Texas members of the Honda Sport Touring Association as reprinted from the June issue of the AMA magazine.

1. Texas Route 118 from Kent to Study Butte: Phenomenal curves, beautiful desert scenery and rich history in southwest Texas. The northern portion runs through the Davis Mountains, with tight twisties, smooth sweepers and the McDonald Observatory in Fort Davis at 6,800 feet. Farther south are the Del Norte Mountains, and farther still are the open, desert plains of the Chihuahua Desert, where you can see forever. The capper is Study Butte and Big Bend National Park, an out-of-the-way desert mountain region filled with unusual lava landscapes, smooth, fast sweepers and (be careful!) strict park rangers.

2. Texas Route 170 (El Camino Del Rio) to Presidio: The ghost town of Terlingue gives way to a spectacular 50-mile ride through lush. twisting valleys, where wind-carved red-and-purple rock rises 1,OO0 feet off the Rio Grande river in southwest Texas. Threading through the Bofecillos Mountains formed by two ancient lava flows, the route takes you up a 15 percent grade at one point, winding up at Fort Leaton State Historic Site near Presidio.

3. Texas Route 16 between Liano and Bandera: Pleasant terrain with a bonus: There is little traffic on this 100-mile bit of asphalt heaven in central Texas. Route 16 is full of scenic elevation changes, sweepers tight switchbacks, beautiful vistas, wonderful tree-covered tunnels and gorgeous, clear rivers that invite the occasional wading party. Be sure to stop in Fredericksburg, where museums and quaint shops line Main Street. And the huevos rancheros at the Old Spanish Trail Restaurant in Bandera are tops.

4. Texas FM 337, from Medina to Camp Wood, then Texas Route 55 north to Rocksprings: A roller-coaster ride that rips up and over huge limestone karsts recalling scenes from John Wayne movies in south central Texas You really can't go wrong picking any of the FM (Farm-to-Market) roads in this area, but FM 337 is unquestionably among the best. Don't miss Last Maples State Natural Area in Vanderpool.

5. Texas FM 1431, from Marble Falls to Cedar Park: This loop around the northeast side of Lake Travis is the tightest, gnarliest, nastiest, hilliest piece of two-lane blacktop in Texas. This amazing central-Texas road has more converts than a Billy Graham revival. Ride it. You won't be sorry.

6. Texas Route 4, from Palo Pinto to Granbury: Starting 12 miles west of Mineral Wells, Texas Route 4 heading south offers spectacular bluffs and scenery through the Palo Pinto Mountains, and it twists and turns all the way to Santo in east-central Texas. Palo Pinto Museum boasts an Old West jail and log cabins. Don't miss lunch in the Nutt House. a historic restaurant and restored country inn dating from 1893.

7. Texas FM 390, from Burton to Independence: Save this for one of those hot days, and you'll really appreciate the rich ice cream at the Blue Bell Creameries in Brenham in southeast Texas. FM 390 (get a good map) east and west from Independence offers attractive scenery and exceptional vistas. It is especially colorful around mid-April, during bluebonnet season.

8. Texas Route 852, southeast from Winnsboro: Typical northeast Texas-lots of piney woods, gentle hills and curves, Winnsboro was founded in 1854 and sponsors one of Texas' best-known salutes to fall foliage, the Winnsboro Autumn Trails. Held every weekend in October, the festival offers sightseers self-guided tours of east-Texas forest land.

9. Texas Route 224, north from Coldspring: Located between Sam Houston National Forest and Lake Livingston in east Texas, Route 224 is made up of hilly sweepers and great scenery. You'll need a good map to find it, and the great U.S. Forest Service roads nearby in Sam Houston National Forest, but your search will be richly rewarded.

10. Texas Route 762. south from Richmond to Brazos Bend State Park: This open road through southeast Texas will surprise you with nice sweepers through the lush cotton fields of the Gulf Coast plains. The park is a must-see 4,897 acres including the Brazos River bottomlands, beautiful live-oak woodlands draped with wild grapevines and Spanish moss, and oxbow lakes and marshes.

Disclaimer: The following information has been collected from various sources on the Internet and publications for the expressed purpose of providing NTNOA members with useful information for the enjoyment, maintenance & preservation of old British & European motorcycles. While the information is intended to be as accurate as possible it can not be guaranteed to be 100% correct, therefore the reader should use good common sense and safety before implementing any of the suggestions and ask questions if in doubt.

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Revised: January 05, 2018 .