Myths, Legends, and Rumours – a talk by Phil Hannam for the Surrey section on 8.2.2017

 

Myths, Legends, and Rumours – a talk by Phil Hannam for the Surrey section on 8.2.2017

 

Phil Hannam the Norton Twins specialist came along to the Surrey section at the Stepping Stones, in Westhumble, Dorking, on the 8 February 2017 to give us a very in depth talk on a variety of Norton topics. We had 18 members and guests turn up for this very memorable event. Phil also used a projector, which was very ably sorted out by our own Dave Cooper after some initial glitches. Mike Duffell provided all the other technical components so that photos and diagrams could be shown on a large screen and so help make some aspects of the talk a little clearer.

I brought along some AMC1 and AMC2, inner gearbox castings an ex works Norton factory 650cc racing twin bottom half and a set of crankcases for the Unified Twin. The latter item gave those who attended a chance to see how that engine had been designed and constructed back in 1959.

 

Phil started his talk by showing the third Norton he owned. This being a Slimline framed 99 Dominator purchased as an Atlas rolling chassis and boxes of bits which was then reconstructed into a café racer.  After selling off the mudguards, seat and tank, he had enough cash to purchase the special Ian Kennedy café racer parts he needed. The bike came from dealer in Hornchurch, Essex who specialised in selling off motorcycles belonging to deceased owners. In the building next to them was funeral directors called Masons. The previous owner of Phil’s acquisition, having come to grief while racing it. Phil said that he had rung all the names in the bike’s log book, using a London Telephone Directory to help as all were listed as from that city. This paid off when he managed to track down the very first owner, Edward Warwick, who was able to tell Phil that the bike had been purchased with a view to being used as a production racer, Consequently, it was ridden competitively around most circuits in the South of England and even taken the IOM TT races, in 1967, but failed to qualify. When Phil bought the bike he subsequently found that the gearbox was very special, containing close ratios that enabled him to achieve 85mph in second gear.

Phil also went on to relate about once riding this bike to Weymouth and having to pull into a garage for fuel. The very elderly attendant claiming that he was one of the two delivery boys on the Bovington Road, at the time, when T.E.Lawrence so sadly lost his life while riding a SS100 Brough Superior. A few years later, while working in the Middle East and crossing through Oman to meet a contact based at a small oasis, he met another old person who claimed that he had riddenwith Lawrence in battles against the Ottoman army.

Phil then showed the audience some new photos of the Jack Moore designed unit construction twin he had discovered a few years ago. This prototype version had a shaft drive unit added to the gearbox and apparently had ended up in the possession of the Trusty Tractor Factory with a view to them using it as an alternative to the Big 4 single already powering of their machines. Some pictures of the assembled engine were shown along with a very intriguing single cylinder OHC engine of unknown make and size along side the twin engine. The Jack Moore cylinder head and barrel are very Triumph twin in their design and construction and a conflict with patents could have been one reason the Moore twin was not put into serious production. Phil has discovered, through his very intensive research, that enough parts for six engines were produced with at least two constructed and used for testing. The engine number has been tracked through the Norton Factory records that indicate it was designed in 1944 and listed as the first Norton Twin cylinder engine built post-war. A full two years before the Model 7 appeared.

Norton and early Commando drum brake shoes were then examined with a picture displayed to show the small differences between the three different types, one rear and two front types. The twin leading and single leading shoes may look the same but they are not.

The Norton clutch then came in for an in depth explanation. Phil mentioning that owners sometimes try to fit old parts and new parts into the same clutch which can then lead to problems with slipping.  A similar problem can arise with new brake shoes. This being due to the new friction material being slightly larger or in a different position to the old. The newer sections then lying over the edges of the old wear ridges and causing only partial gripping until bedded-in.

I had brought along some inner gearbox castings parts for the AMC1 and the AMC2 gearbox’s, to show the differences between the kick-starter springs locations.  The earlier spring was a bad design and broke very often due to being weak and not coping with frequent use. The later kick-starter spring was a much better and stronger design having less stress on its ends than the earlier one. We were then shown five recently purchased versions of the pawl gear change spring 040038. All were different in appearance with four of the pattern ones not allowing gears changes when using the lever. So the advice is to only buy correct original manufactured parts, as these will operate as per the manufacturer intentions.

Phil showed us this spring in its position in the outer cover. It has a cranked leg that will only let it work correctly when mounted, in the cover, one way up. Lots of people fit this piece incorrectly when rebuilding a gearbox. Phil asked us if we could explain why this spring was not reversible.  Simon Smith came up with a very plausible explanation that the cranked part was to help the end line up with the other end. Both these ends then sitting in respective grooves in the gearshift pawl. Fitted in any other position and the spring ends jump out of the pawl and subsequently selection of some gears becomes impossible. Well that works for me.

 

 

The other Achilles heal of the gearbox was the clutch operating mechanism lifter arm 040029. Phil has devised of a small modification that should aid the better operation of this mechanism and therefore make the clutch much easier to operate. He showed us a diagram of the modification.

The gearbox internal arrangement was then shown using the projector and Phil went through the lay out and how it all worked. He also explained, in greater detail, what can go wrong, and some of the inherent problems with it. Especially the causes of Layshaft failure and 3rd gear whine. Thanks to Les Howard for his very useful schematic diagrams. Also shown were some of the gearbox main shaft modifications that are commercially available to stop oil being sucked along the inside the primary case and then contaminating the clutch plates. It is Phil’s belief that this problem is mainly caused by faulty mainshaft oil seals allowing oil from the engine into the primary cases. He said that the real culprits are poorly manufactured, cheap seals that fail very quickly. A similar problem existing with Timing cover seals. These do not work as intended, often actually allowing oil to pass each way through them and in the timing cover contributing to wet-sumping.

Phil then put up a list of common motorcycle rear chain sizes and went on to explain the Reynolds number system that is shown on their chain packaging and how it equated to modern chain sizes. The big surprise being that the newer metric style numbering is actually based on old imperial measurements. The first digit representing 1/8ths on an inch for pitch and the second and third digits representing roller width, again in 1/8ths of an inch. So a 530 chain would have a 5×1/8 = 5/8” pitch and 3×1/8 = 3/8” roller width. The 3rd digit being 1/10ths of an inch to be added to the second digit on some chain sizes.

 

We were then shown the Commando Triplex primary chain and how it was a much better than the single strand chain as used on the Dominator twins. Its design helping to prevent the clutch main-shaft from bending too much and also helping to keep the diaphragm clutch body in alignment. The deep groove ball bearing used in the Commando clutch tends to allow the basket be pulled over towards the engine, especially when it becomes worn.

 

We were then shown some photos of really badly spoked Norton wheels. This is one of Phil’s pet hates as whenever he goes to classic bike shows he regularly spots many badly rebuilt wheels. Most people in the room agreed that these were so bad they would not like to ride a bike with those shown. The correct spoking pattern was then displayed and how the rim should be correctly laced to the hubs.

 

 

The different low and high-pressure rocker arm feeds were explained to us. Lots of new owners end up mixing or miss-fitting rocker parts, which then results in smoking engines. Phil explained that the smaller 500cc and 600cc twins do not really need pressure fed rocker arms plus large capacity pumps and 6 start worm drives. The cylinder head can leak from several places tricking owners into believing they have a dodgy head gasket. One being the exhaust rocker covers because if they leak, rather than checking the gasket surfaces are good; owners will just tighten then over-tighten the rocker cover nuts. This then pulls the metal surrounding each thread up, forming a slight bump which holds the cover away from the respective mating face and preventing a good seal. Both the rocker covers and the spindle covers can also leak oil if too much crankcase pressure is finding its way up to the cylinder head. If you are very unlucky then you may have a cylinder head that is porous and leaking through the casting. I saw this when I worked at Gus Kuhn Motors and a cylinder head had to be returned due to a porous casting.

 

Examples of the three main cylinder head gaskets were then displayed and the differences shown between them. They fall into three recognizable groups. 500, 600 and 650cc engines with straight-sided gasket. Then 750 Atlas, Hybrid and 750 Commando engines that all have rounded gasket sides. Finally 850 engine head gaskets which are also rounded but much larger, especially on the carburettor side.

Like the rocker cover nuts, Phil mentioned that those on oil pumps can also be over-tightened with a similar consequence. The pumps stud nuts pulling and distorting the mating surface. He suggested that a gasket always be used to over come this difficulty if the oil feed casting base has become distorted with use. During a major rebuild this oil pump-mating surface should always be checked for distortion and dressed back if needed.

 

Phil then explained about how the holes in the crankcases are drilled to lubricate the timing gears, cam chains, camshaft, and camshaft followers. He mentioned how these oil holes worked in Norton twin engines by using a bellows effect and actually how very important they were for providing lubrication to the oil pump external gears. We were then shown pictures of how an owner had drilled many more holes in his crankcases in the mistaken belief that this would help to stop oil leaks by adding numerous extra breathers. Completely ignoring the weakening then caused to the integrity of the cases. Especially near the camshaft tunnel, or the effect on internal lubrication of bearings, timing chains etc.

 

Some six different varieties of Roadholder fork sliders then appeared up on the screen. Phil then asked us to guess how many varieties of these were produced in total?  The answer being at least 16 recorded in the parts books if later disc-braked Commando models are included. On a similar theme, he said that there are at least eight different twin timing covers produced for the Norton twins and more than 6 gearbox outer covers. None of this really helping when rebuilding a ‘basket-case’ Norton.

 

Going back to historical Norton’s, we were then shown the Norton 500cc side valve twin with the frame number 48187 that is now in the Sammy Miller museum. Phil has also done a lot of research concerning this very unique Norton twin. Phil has now ascertained that two of these models were actually built. One was dispatched to the army and the other to the Forestry Commission. Phil then explained the history of this model, and that he is still trying to find what happened to the other missing 500cc side valve twin. Stan Dibben had told Phil that he delivered both.

 

Phil then finished with the question of the accuracy of torque wrenches. Between myself, Phil and Ken Rawlinson we had a number of different types of wrench to look at. Phil demonstrated the accuracy between the torsion beam type and the tubular twist, compressed spring type. Pointing out that a good many owners leave their compressed spring torque wrenches on the setting that was used last. Over time, this can weaken the spring and change its accuracy drastically with disastrous consequences if torquing up the likes of a crankshaft. Some of them are just not that accurate. Phil explained that a few years ago a Motoring Magazine test was done on both new and old torque wrenches and found that at the low end of the range of settings some were over 50% out. I had brought along an American made beam torque wrench and this one always returns to zero, so this therefore must be more accurate that the tubular type. After what Phil has explained I shall use this from now on. I am sure this will elicit some comments from the members after this part of my article is read.

 

The Surrey section has many more talks being arranged through out the year, as well as a Branch presence and stand at the following events. The Kempton Park Classic Bike Show, 20 May 2017, Brooklands Bike Show, the Horsham Festival 6-7 May 2017 and the motorcycle display part will be on the Sunday 7th May. The Capel Motoring Show, Warlingham Rugby Club Classic Car and Bike Show, and in October the Ardingly Classic Bike Show on 29 October 2017. For a full list of our events please contact our secretary Ken Rawlinson.

 

Can I extend the Surrey sections thanks to Phil Hannam for taking the time and the effort to come along and give us this very in depth and informative talk? Also for Phil casting his very expert eye and editing changes to the above texts for me. For those that could not make it along you missed an amazing evening that was hugely informative. Can I also give a very warm welcome to those members of the NOC that arrived for the talk who were not members of the Surrey branch, and hopefully you will be encouraged to join the Surrey section in the not to distant future. One being Michael that I spoke to and hopefully he will join us again.

 

Any mistakes in the above narrative are purely mine and are therefore unintentional.

 

Also may I extend all our thanks to Mike Duffell, Dave Cooper, for helping Phil with the projector and also its operation? We rocked it totally.

 

Anthony Curzon

Press Officer for the Surrey section

 

Other Upcoming Events
Jan
10
Wed
7:45 pm Club Night @ The Stepping Stones PH
Club Night @ The Stepping Stones PH
Jan 10 @ 7:45 pm – 10:45 pm
Club Night @ The Stepping Stones PH | Westhumble | United Kingdom
We’ve Moved! – Come and find us at our new Meeting venue of ‘The Stepping Stones’ in West Humble – just down from Ryka’s near Box Hill. It’s still the 2nd Wednesday of each month[...]
Feb
14
Wed
7:45 pm Club Night @ The Stepping Stones PH
Club Night @ The Stepping Stones PH
Feb 14 @ 7:45 pm – 10:45 pm
Club Night @ The Stepping Stones PH | Westhumble | United Kingdom
We’ve Moved! – Come and find us at our new Meeting venue of ‘The Stepping Stones’ in West Humble – just down from Ryka’s near Box Hill. It’s still the 2nd Wednesday of each month[...]
Mar
14
Wed
7:45 pm Club Night @ The Stepping Stones PH
Club Night @ The Stepping Stones PH
Mar 14 @ 7:45 pm – 10:45 pm
Club Night @ The Stepping Stones PH | Westhumble | United Kingdom
We’ve Moved! – Come and find us at our new Meeting venue of ‘The Stepping Stones’ in West Humble – just down from Ryka’s near Box Hill. It’s still the 2nd Wednesday of each month[...]
Apr
11
Wed
7:45 pm Club Night @ The Stepping Stones PH
Club Night @ The Stepping Stones PH
Apr 11 @ 7:45 pm – 10:45 pm
Club Night @ The Stepping Stones PH | Westhumble | United Kingdom
We’ve Moved! – Come and find us at our new Meeting venue of ‘The Stepping Stones’ in West Humble – just down from Ryka’s near Box Hill. It’s still the 2nd Wednesday of each month[...]
May
9
Wed
7:45 pm Club Night @ The Stepping Stones PH
Club Night @ The Stepping Stones PH
May 9 @ 7:45 pm – 10:45 pm
Club Night @ The Stepping Stones PH | Westhumble | United Kingdom
We’ve Moved! – Come and find us at our new Meeting venue of ‘The Stepping Stones’ in West Humble – just down from Ryka’s near Box Hill. It’s still the 2nd Wednesday of each month[...]