Item 2: 1938-39 Works Conical Rear Hub

Bikes and Project Builds

The First 'Conical' Type Rear Hub Norton Made

If I was to choose my own favourite period for the development of the racing single cylinder Norton models - and the Works development versions of these engines - I would have no hesitation in choosing the period from approximately 1935 through to 1939 (at which point WWII put a hold on all competition development for the next 5 years).
Norton's development of the overhead camshaft engine had started (arguably) in 1927, with the first Walter Moore designed SOHC engine (commonly referred to as the 'Cricket Bat' engine due to it distinctive timing cover shape) and continued all the way through until circa 1963, when the last few production DOHC Manx Norton racers were assembled for sale from remaining parts - by that time a very different and more powerful motorcycle, a world apart from the first models back in the 1920's - and spanning an amazing 37 years production period. No wonder the Manx Norton (as the racing version was most commonly known) is still commonly regarded by many as the most successful motorcycle racing model of all time.

Late 1930's Works Rear Hub - The First Conical Type

A recent acquisition from a close friend, and owner of many Norton Works parts (well the hub assembly is anyway) - a wonderful rectreation of the first 'Works' type conical rear hub, fitted in the late 1930's to the special Works Nortons

The brakeplate and shoes in the foreground are from my own stock - the brake plate being an oddity I have had for many years - but will be amended to take the correct type Manx rear brakes shoes - which are also shown, and are original, see the article for more background

Distinctive 'Conical' Profile

Here you can clearly see the Conical profile of the rear hub, and how it blends into the brake drum with the distinctive cooling fins

Below is that great rider Freddie Frith on a 1938 Works Norton at the TT - very different to a production SOHC racer, and by this time, with DOHC cambox, tele front forks - and just visible - the conical rear hub type shown above

Works Development Parts - 1930's

But going back to that 5 year'ish period from the mid 1930’s to late 1939 - that would seem to me to be the period when the Norton Works racing team were at the absolute height of their success, and pushing the boundaries of development, which was evidenced in how the out and out racing version of their venerable camshaft engine was starting to differ from the roadgoing equivalent.
And not only was this true of their engine development – but of the chassis and braking development as well. 1936 saw the Works bikes chassis having some major changes – i.e. the introduction of the ‘Big Plunger’ type rear sprung frame (used by the Works bikes in 1936 and 1937, and offered to customers in limited quantities in 1937 and 1938), alloy wheel rims (painted black) – and bigger front brake drums. The rear brake drum was still the 7” drum/sprocket type – but I believe some Works ones were fitted with cooling fins. However, 1937 saw the introduction of the iconic ‘Conical’ front drum (magnesium I believe on Works bikes, but conical front drums were later introduced on customer race bikes, with an iron conical drum and magnesium brake plate and shoes.

The 1938 Works Norton Models

Then in 1938 the Works bikes received a major redesign – and although still looking superficially similar to the production/over the counter sprung frame racing models (which themselves were sometimes referred to in the Norton records at this time as ‘Full Manx Spec. SF’ – an early reference to the famous Manx Norton moniker) - they became arguably as far removed from the Production racing models as they ever got! In short – the new 1938 Works chassis was tubular in construction (and never offered to the public – instead in 1939 Norton introduced the visually similar but very different Gardengate frame on Production bikes) and introduced telescopic forks for the first time (planned for 1940 on production bikes, but with WWII getting in the way – not finally offered until 1947).
The 500cc engine stroke/bore was changed to 82 x 94.3mm, the crankcase was re-designed to make it stronger – which became the forerunner of the Featherbed Manx style engine, it was DOHC – which was not offered to customers until 1949-50 (of which more in Article no3) . . . and finally - as well as the larger conical front brake as used the previous year – this 1938 Works chassis also introduced a newly designed conical rear hub with integral brake drum. And although this brake drum still used shoes of 7” diameter (the conical front drum was larger) – the actual brake shoe area was much wider, and employed magnesium brake shoes pivoting on a single pivot pin, using a ‘scissor type’ interlocking brake shoes design.

Supposedly, when Freddie Frith first rode this new 500cc bike in anger in the 1938 NW 200, he commented afterwards that the braking and roadholding were astonishing – and although he did not finish that particular race – it was clear that all these changes had helped immensely and helped keep the bikes competitive against growing European model competition for a few more years.

As far as that early rear ‘conical’ brake drum was concerned – they were never offered to the public in that form, only being employed on the 38-39 Works bikes pre-war. After hostilities ended and top level competition resumed in 1947, the same bikes were picked up again by the Works team, and used with only minor modification until the introduction of the first Featherbed Works bikes in 1950.
However, in 1948 the conical rear brake did have a revision to its brake plate design – it becoming a very trick twin leading shoe design – with an internal scissor plate spanning the diameter of the brake plate to operate both cams together. I have actually seen this design in the flesh (from a close friend who has one) – but will not be trying to recreate that design myself – luckily my hub is to be fitted to a pre-war model . . . so I was able to easily convince myself to dispense with that idea! However, alongside – I have included a line drawing of that 1948 TLS design, taken from one of the two motorcycle ‘weekles’ at the time.

Brake Drum View

This hub is a faithful reproduction of the original pre-war conical hub, as used on the Works racers only. Reserved now for my 1939 500cc Manx Norton build - which is progressing well.

It is already fitted with bearings - and although I have not checked sizes yet, will expect they will be similar to the post war (production) conical type. Sprockets I already have a number of available (but need to check they fit!)

The Hub I have Acquired

So, to the hub I have acquired. Well, as with the Works 54 type carburettor re-creation covered in the first of this 3 part article, a good friend of mine had mentioned it to me some time ago, as he had gone to a lot of trouble to recreate one many years ago for his own pre-war Works bike, and having gone to all that trouble, had ended up having two cast at the same time.
Knowing that he is now in his twilight building years he offered me the opportunity to acquire this second hub, him being aware I have an interest in such things – and am also currently building a 1938-39 500cc Manx Norton with some semi-Works spec parts – this being my 1939 Gardengate chassis 500cc Manx Norton, but with a full magnesium twin spark engine.

Now as it happened, I already had an absolutely lovely and time-warp original (Production Manx) pre-war Manx plunger hub already lined up – this still having its original Norton spokes to a genuine pre war 20” alloy (Rudge Borrani) rim – yes genuine 20” alloy rim! – as per original Manx’s of that era. This particular wheel is shown in the photos below. Although having a good layer of surface rust on the spokes and hub centre – I had considered that a light media blast (first carefully masking the bearings) should remove the surface rust, and provide a good ‘key’ to allow a satin black 2-pack to be applied . . . so retaining the original Norton butted spokes.
However, although I have got a 20” Avon SM tyre lined up to go on this rim – and it means it would look very original, I know that if I do track parades (or possibly the occasional twisty sprint) on this bike later on – the 20” rim will limit my tyre choice and stop me putting a soft racing compound tyre on. Therefore, with that logic – and knowing I could never turn down the opportunity to own such a lovely trinket as this hub – I very quickly resigned myself to raiding the savings piggy bank again . . . and foregoing any other frivolities for a few months, to help pay for it!

I picked up the Works type hub back in the Autumn of 2024, and actually – as I write this in Spring 2025, I have not done too much with it yet – as I have been too busy with some (work related) machining tasks on the CNC machine, and what little time I have had on the 1939 Manx has been spent finishing off its close ratio Dolls Head gearbox – the subject of another future article.
However, when I did look the hub over, I could see that it looked beautifully made, to all intents and purposes, faithfully replicating the profile of the original Works hub design – and has already been assembled with central tunnel and bearings already fitted.

Differences to Later Production Hubs

For those that are fortunate enough to own either a 1950 Gardengate Manx or a later Featherbed DOHC Manx Norton – they will probably be able to spot quite easily a few subtle but significant differences on this early design that did not make it through to the magnesium conical hub that made it through to the later Production Manx’s. The conical rear hub fitted to genuine Featherbed DOHC Manx Nortons were all fitted with a conical magnesium hub – and this has become an iconic and much copied feature for anyone wanting to build a Featherbed based café racer (I well remember later 1960’s BSA conical hubs being employed for this purpose). Therefore it is probably widely regarded that the Featherbed Manx Norton had had this conical type hub designed specially for it.
But that is not the case – it was actually first fitted on Production Manx’s in the last year of the Gardengate (plunger) Manx Norton – i.e. the 1950 models, and these are actually shown in the 1950 Norton Spare Parts list (alongside the more common plunger type hub), The only significant difference I am aware of from the Featherbed version that followed, was that the brake plate on the 1950 Gardengate versions had a square peg on the plate to allow it to slide into the plunger vertical slide casting – just as the normal pressed steel 7” brakeplate did on those plunger models. And of course, knowing this, it is more evident that the conical design adopted in 1950 was actually a ‘Production’ development of the earlier Works hub shown here.
The two noticeable differences on this earlier Works type design are subtleties in the profile shape - and most noticeably – you can see that where the narrow (non-brake) side of the conical profile blends into the bearing support – there is just a smooth curve. I am supposing that Nortons must have realized this was a potential weak point, with possibly – not enough ‘meat’ in the casting. Therefore if you look at the photograph of the hub fitted to my own 1955 Featherbed Manx below, you will see that the production hub had a pronounced lip to the casting where the spokes protruded.
It should be noted that the same was true of the earlier (up to 1950) conical front hubs and those that followed. The early conical hubs (i.e. pre-Featherbed) had a similar smooth blending at this point where the spokes fed in – but for production racing bikes these were cast iron. When the magnesium alloy conical hubs were introduced in 1950 they too incorporated a strengthening lip in this area (although I have what I believe to be a Beart alloy conical front hub which does not – almost a hybrid of these two designs!).

Another View of Original 1939 Works Bike

This original factory photograph provides a great view of all the special features of that 1938-39 Works model - including a nice clear view of the conical rear hub

Note the tubular plunger frame - only used on this model of Works bike - and the unusual and easily noticeable large filter canister (at least - I think it is an oil filter!!)

And below, a picture of the same Works bike - but this time Post-War in 1948 - when the addition of an external damper was added, as well as a TLS shoe brake arrangement , see below

There is also a subtle difference in the outer profile on the brake side of the earlier Works type hub – but this is less pronounced and only noticeable when doing a direct comparison. And as is so often the case when looking at these Works development parts – it is so interesting to look at the detail, as it helps to understand the lineage of the Production models that followed.

Just a final note on the subtle differences on the original production type magnesium rear hubs. I am told that the earliest rear conical hubs can be identified from later ones if you feel behind the cast spokes on the brake side. Later ones will have a small rib that can be easily felt with the fingers – while the early ones do not. As many collectors will know – magnesium alloy can sometimes fracture, and Norton’s must have realized more meat in the casting webs at this point was a good idea – particularly as some were used in sidecar racing.

Brake Shoes and Variations

As far as a brake plate and shoes are concerned - when I was offered this hub, I knew it did not come with brake plate or shoes but I was not too concerned, because I had something in mind. A few years ago I had acquired an unusual Norton oddity – a rear brake plate that looked very much like a Norton rear brake plate – but in alloy. It did come with shoes, but the normal road type twin pivot bolt design – not the Manx racing type, but I had been looking for a use for this brake plate . . . and although with a little fettling, it could be fitted with the original road shoes still fitted – that would be a waste of all that extra brake capacity that the extra width of the brake drum provides!
So my view will be to carefully alloy weld up the hole locations for the original twin pivot bolts, weld in a strengthening plate as well, then re-machine it to provide the Conical style single pivot bolt that would allow bigger Manx rear brake shoes to be fitted.
Having decided on this route (this being before I had actually even picked up the hub from my friend – don’t we all like to re-plan and scheme our build projects as parts present themselves!) , I decided to just have a quick rummage through the cupboard of racing brake parts I had acquired over the years. . . . just to double check – but although I knew I had a couple of pairs of original magnesium front brakes shoes (with plates) – I was almost positive I had no conical rear shoes (i.e. 1950 Manx onwards on production bikes) – and would probably require a call to Andy Molnar to purchase a set of his.

Works 1948 Rear Brake Plate - Twin Leading Shoe Upgrade

This original factory line drawing from one of the 'Weekly Rags' shows the clever internal plate that joined the openening cams of the TLS rear brake plate design - introduced on Works bikes in 1948 and never copied over to any Production Manx models

I will not be trying to replicate this type of brake plate!

He Put In His Thumb - and Pulled Out A Plumb! (well sort-of!)

Therefore imagine my joy and delight as I went through the box – to find almost hidden in a supermarket carrier bag – a pair of genuine magnesium rear conical shoes I did not even know I had!! Jammy bugger I hear you say – and quite right too!, they must have come from one of the deals I did a few years ago – but although I vaguely remember the bag – I thought at the time they were ‘fronts’, so am over the moon to find they are actually ‘rears’ and exactly what I am now looking for!

As you can see from the photograph on the right - thsee shoes are original conical type magnesium alloy rear shoes, still with their original chromating in place - and importantly, nothing but the barest of surface corrosion (important with these early magnesium shoes as they can suffer badly with corrosion that can weaken them.

As an added bonus, they also have brand new brake shoes already fitted - in what looks very much like a racing compound - double bonus! They are bonded on rather than riveted, so I suspect these were done in more recent years - although it would have been nice if they had been long enough to cover the full shoe length available (see end area of the shoes, where the casting has bare rivet holes, without lining) - but that would be me just being picky!

Now Reserved For 1939 Gardengate Manx Build

So that is where I have got to at the moment.
It should not be very long before I get to ‘lacing’ this hub to a rim, and have in mind an alloy 19” rim of the normal flanged type, as I was shortly going to be addressing wheels on the 1938 Manx build anyway.
This will allow me the wider choice of tyres – and I will almost certainly look for an Avon GP in competition compound.

As far as finish is concerned – well I know the two pictures of the original Works Norton with this hub fitted – show the hub to being finished with a silver look, but I just cannot bring myself to do it in silver.
I know they finished some Manx magnesium engine castings in silver postwar – but I have always thought Norton magnesium (hubs and engines) look best either in original black/dark grey chemical chromating, or for hubs – painted black, as per my 1955 DOHC Manx conical rear hub – shown below.

I may decide to do this hub in a satin finish – but am almost sure I will finish it in a black 2-pack finish, which will offer best protection for a long life.
As far as all the smaller bits - like spacers and the correct length brake arm - i.e. a shorter length on the plunger Manx rear hubs, if the original production hub and pressed steel brake plate is to be used - but a longer curved style brake lever on the Works type, well I have a longer type production brake arm - but I might end up making a Works type one in alloy, and I also have both short arma and long arm Manx brake levers of the correct period - so can decide which is best for the job, once the wheel is built and in place. Lacing hubs to rims is not my favourite job, but when my wheel builder retired a few years ago, I forced myself to learn! - so once I have figured the correct spokes needed, I will no doubt reserve a Sunday to taking on this task - and look forward to fitting the final end result - I will keep you informed of progress in a future article.

A Lucky Find In 'Racing Brake Bits' Box - Original Conical Rear Shoes

I was expecting to have to buy new (reproduction) Manx brake shoes

But a lucky find while searching thruogh my 'brake spares' box was a genuine original pair of conical rear hub (production type) rear shoes - Wahhay. I had not checked before and thought they were fronts

Shoes Fitted in Drum

Final picture shows the magnesium brake shoes loosely fitted into the brake drum - more about these in the article

The rear shoes fitted to Manx conical (racing) rear hubs had a much bigger brake shoe area than the normal plunger rear hub (fitted to production Manx's up until 1949)

Lineage of Rear Hubs Fitted To Racing (and Works) Model Nortons

Although not conclusive - Below I have shown a selection of rear Norton hubs, that show some of the variations fitted to racing Norton models (i.e. SOHC and DOHC racing singles) through the 1930's - 1960's. I am sure there were a few others I have missed . . . but these are the main types I am aware of - including pictures of many of the Works rarities

Early SOHC (Works) Bike Brake

This very early Arthur Carrol type SOHC bike is easily identifiable as being from an early period - probably 1930-31, as the early '3-stay' rear frame is clearly visible, and I believe is either Works, or Works supported.

With thanks to good customer - Phil Newstead, this bike was photographed at the NOC 100th Anniversary celebrations - and clearly gives a good view of the early Norton brakes, which were seperate to the sprocket and based on the style of seperate (RE type) rear drums. I believe similar drums were employed on Brough Superiors of the period

1934-35 Works Bike Rear Wheel

This bike belongs to another well known Norton colletcor and friend - Neal Ford

I believe this bike is a genuine 1934-35 Works Bike, and I wish I had taken a better photo of the rear wheel. I vaguely remember it might have had an alloy muff over the (plain type) rear brake drums, with fins, but as you can see - it was still employing the standard pressed steel 7" rear brake plate - still fitted to most road models well into the late 1950's.

More interesting is the front brake on this bike, shown below. This looks like the last Works version of a Works brake - prior to the introduction of the Conical hub - but although non conical and 7" diameter - has a coolling fin muff and a cast alloy brake plate is just visible

Last Year of Works Rigid - 1935 TT Bike With Jimmie Guthrie Aboard

This was the last year the Works team used the Rigid frame - and this lovely period shot shows Jimmy Guthrie aboard the 35 TT bike, with a rear brake looking like the roadgoing 'Cotton reel' type - but with much extra finning around the brake drum

Note also the twin-spark BTH magneto, used just a few times in 1935-36 supposedly - I am very lucky to have one of these rare magnetos on my Gardengate Manx - of which the engine is very similar to this 1935 SOHC full magnesium Works spec

First Works Plunger - 1936-37 Rear

The unusual angle of this photograph gives a good view of the heavily drilled suspension of the first plunger Works type suspension - coined 'Pepperpot' because of the liberal lightening holes

It it difficult to make out to much detail of the brake - but you can just make out some heavy finning of the brake drum and what is very probably an alloy/magnesium brake plate - although I cannot be sure. To my knowledge the few similar framed producton Manx spec bikes used the normal pressed steel brake plate

Pre-War Plunger Manx Brake with Alloy 20" Rim

This very early Arthur Carrol type SOHC bike is easily identifiable as being from a very early period - probably 1930-31, as the early '3-stay' rear frame is clearly visible

A Pre-War Anomoly?? Is it Real???

I have had this rear (??) hub hung on the wall of my workshop for a few years - it coming from another good friend of mine - and collector of anything cammy Norton

At first glance it looks like a slimmer variation of the Works type pre-war Conical hub shown at the top of this article, and is certainly an interesting hub to look at

I suspect though it is actually a front conical pre-war typ racing hub - that may have been converted to a loose copy of the first Works type concical rear hub. An interesting talking point never the less - and as my mate said . . . it has a nice original rim on it!!

Postwar 1949 Rear Hub - Gardengate

This lovely 'timewarp' Post-War Gardengate was photographed at the 2009 NOC Cenetnary meeting at Donington and it was so original and untouched /i took lots of photos. Click on the picture above to see a larger version.

You will see it has the normal Gardengate type plunger hub (different to the rigid framd cotton reel type, with 3 studs and 3 dowels locating the brake drum - and a finned brake drum (although I have seen earlier ones pre-war without fins.

Note that this Manx has the final Gardengate alloy oil and petrol tank, but not a conical rear hub - indicating 1949 early 1950 I think

Below, same bike drive side - still pressed steel brakeplate and smaller shoes. Note short brake arm going under wheel spindle, as well as short arm brake pedal to match - with correct Manx type parrallel serration on pedal (road bikes have cross hatch . . . for those looking for originality on their cammy restoration!)

Conical Rear Hub - Gardengate Introduced in 1950

The last year of the Gardengate Manx Norton (i.e. 1950/51) were the first Production Manx's to adopt the magnesium conical hub - as shown here with the one I have loosely assembled for my 1950 DOHC Manx Gardengate project

I have bearings and alloy centre spacer ready to fit - although I think the first gardengate ones continued to use the special 'wasted' spindle used on most plunger rear wheels

And below is the first Norton publication of the magnesium alloy hubs - this taken from the 1950 Spare Parts List. Note the rear brake plate which was a 'one year only' version - with square peg to fit into the Gardengate plunger slide castng - luckily I have the correct brakeplate for this project

Final 'Works' Type Rear Hub - Seperate Sprocket and Brake Hub

When the Featherbed Manx was introduced in 1950 it was only available for the Works team - (and I think, continued with the earlier conical hub, rather than the Production type flanged version). But as shown here - in 1952 the final Works version was introduced, with brake hub on timing side, and drive side just haveing a solid alloy sprocket as shown on this 1953 Works bike. This type fitted to Works bikes until their last year of exotic spec - ie. the end of 1954

The picture below shows the design of the rear brake hub and TLS brake plate, in magnesium of course, with fins that get wider as they move outward towards the brakeplate.

Shown is an excelllant reproduction from that excellant DOHC Manx stalwart, Andy Molnar

Reproductoin Works Hub on Andy Molnar's Bike

Conical Rear Hub - Production Featherbed Manx (through to 63)

And above is the original rear hub fitted to my 1955 DOHC Norton - which is the normal place you expect to see one of these conical rear hubs.

This style of magnesium conical hub continued on Production Featherbed Manx Norton's all the way through until the end of Manx production (the last of which were sold in early 1963)

The picture below shows the webbed casting style of these Production type conical rear hubs.

You will notice the design of the webbing looks very different to the earlier Works type casting web - that spanned out from the centre of the hub - once imagines that they must have realised this later webbed design gave more strength and it was also evident on the post 1950 front hubs (both being cast in magnesium)

RacingVincent - Articles: Winter 2024/25

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