Stafford Classic Bike Show - news

Anyone going to the Stafford Classic Bike Show? Please bring your camera or a cell phone with a good camera along. Why? Andover Norton has announced the display of their pre-Mk3 prototype billet crankshaft at their boot.
50 years too late and craved for by so many, it must be the height of product announcements for the classic Norton Commando ever. Please post your pictures here!

- Knut

mdt-son said:

Anyone going to the Stafford Classic Bike Show? Please bring your camera or a cell phone with a good camera along. Why? Andover Norton has announced the display of their pre-Mk3 prototype billet crankshaft at their boot.
50 years too late and craved for by so many, it must be the height of product announcements for the classic Norton Commando ever. Please post your pictures here!

- Knut

Click to expand...

Really really wish they had it done 3 years back. I had to source second hand parts and do the drive side radius modification to replace my cracked crankshaft.

Looks expensive, but certainly a lot cheaper than a destroyed engine, or possibly a serious accident.
They just need to start making Interstate tanks now, as there seems to be a reasonable demand.

Thanks for sharing - I see Arrow are the manufacturer.
So we now have a couple of sources for new cranks.
Times are good... for those with money

Matchless said:

Looks expensive, but certainly a lot cheaper than a destroyed engine, or possibly a serious accident.
They just need to start making Interstate tanks now, as there seems to be a reasonable demand.

Click to expand...

I would love to see a proper reproduction of a steel Interstate tank!

Mark Savage said:

I'm going and certainly going to get a look at it after they announced they were going to produce them in their newsletters.
I'll take a few pictures and post them if no one else has first.

Click to expand...

Thanks for posting, Mark. The crank looks quite convential, which was to be expected, as AN mentioned the objective was to meet the weight (and probably moment of inertia) of the bolt-up crankshaft.
Was there any information about when they will be available for purchase? Target price?

The axial bore concentric to the journals creates an oil reservoir of approx. 75 ml only, despite the large bore of an estimated 1". Twice the amount would be desireable and require drilling a radial bore in the flywheel, Triumph style.
Purpose of the oil reservoir is to provide instant lubrication in the first seconds of running, and to counteract the "water hammer" effect of hydraulic pressure transients at higher rotational speeds,
i.e., ensure a steady pressure and flow of oil at a given rotational speed. Such transients are predominant in engines with an intermitent oil feed through the main bearing journals.
When running the Norton engine with conrods having nozzles which are not blocked, pressure transients of low magnitude are likely to arise.

Lubrication aside, weakening the cheeks is what worries me the most, and the longitudinal bore doesn't necessarily have to cross the drive side cheek.

- Knut

B+Bogus said:

Thanks for sharing - I see Arrow are the manufacturer.
So we now have a couple of sources for new cranks.
Times are good... for those with money

Click to expand...

I wonder if Arrow has spun the crank for a length of time to check if it holds? After balancing for stock reciprocating weights, spinning it at 10.000 rpm for 100 hrs subjecting the crank to cyclic torsional load would be a good merit.

Expected failure modes are either combined bending and shear stress failure at the journal/drive side crank cheek interface, or combined bending + tensile and shear stress in the upper part of the drive side crank cheek.
The combined effect of bending stress due to crankshaft flexing by the flywheel effect (tensile stress at inner side of cheeks!), superimposed by tensile stress originating from torsion, superimposed also by shear stress orignating from torsion and partially from mass forces,
may explain why the crankshaft cheek adjacent to the journal fractures violently in many damage incidents.

Due to the resilient bearing and bearing support, the PTO shaft is not as vulnerable as one might think.

While the crankshaft's mechanical performance can be simulated using e.g., FEM software, which is quite common, I believe simulating the oiling system isn't common at all, and can be quite revealing.
The engine lubrication system is simulated using either CFD software, or a mathematical network analysis model called the "bond graph method". Both will reveal transient pressure and volume flow with revs.
Any simulation performed requires experimental real world verification to assure validity.

- Knut

mdt-son said:

I wonder if Arrow has spun the crank for a length of time to check if it holds? After balancing for stock reciprocating weights, spinning it at 10.000 rpm for 100 hrs subjecting the crank to cyclic torsional load would be a good merit.

Expected failure modes are either shear stress failure at the journal/drive side crank cheek interface, or combined bending/tensile and shear stress in the upper part of the drive side crank cheek.
Due to the resilient bearing and bearing support, the PTO shaft is not as vulnerable as one might think.

While the crankshaft's mechanical performance can be simulated using e.g., FEM software, which is quite common, I believe simulating the oiling system isn't common at all, and can be quite revealing.
The engine lubrication system is simulated using either CFD software, or a mathematical network analysis model called the "bond graph method". Both will reveal transient pressure and volume flow with revs.
Any simulation performed requires experimental real world verification to assure validity.

- Knut

Click to expand...

I knew that Mick Hemmings had developed a crank before making his decision to retire. I thought it was with the support of Arrow, but I have no evidence for that.

I had also imagined that the effort would move to AN with other projects from Mick. But again, my imagination not stated fact.

So, I imagine what has happened is that in taking over a lot of stuff from Mick they also took on the crank. And what might they have been doing? Testing, productionising etc. I would imagine. Which all takes time.

I really doubt they are just gouging them out of lumps of metal and hoping for the best!

SteveA said:

I knew that Mick Hemmings had developed a crank before making his decision to retire. I thought it was with the support of Arrow, but I have no evidence for that.

I had also imagined that the effort would move to AN with other projects from Mick. But again, my imagination not stated fact.

Click to expand...

The late Mick Hemming's project originated in 2015. Mick's crankshaft and AN's crankshaft presented at Stafford are quite different products. As to how far AN took over Mick's project I don't know, I believe they sold off the remaining cranks only,
otherwise the cranks would be on offer today. I know technical @ AN examined the crank and found some deficits in the design, which may have prompted a decision not to pursue with the design / project.

- Knut

The crank is unrelated to Micks which we sold about 5 years ago. We knew who made them but sadly they're long gone, as have Farndon, the family owned firm across the road from Farndon that also made cranks and the supplier in Wolverhampton. If I wanted a crank over 25Kg or a crank for a steamship then I would be spoilt for choice in the UK for a supplier.
The week before Mick fell ill I spoke to him about getting some more cranks, sadly it was not to be, but he did explain what to watch out for.
We needed to have cranks for the road users, but it made sense to have an unblanaced version for those to balance themselves, being EN40B with the mass right out on the flywheel should enable some serious balancing to be achieved.
I have the drawing for the MK3 crank to check through, this is not so straight forward as the 4 original drawings that comprise the crank are incorrect and clearly not what was used to produce MK3 cranks. We will also need to order the MK3 cranks in a suitable number to keep costs down, ideally on the back of an order pre MK3 cranks.

The show was successful for us, and really nice to see some of those that can't get south to our open day. Not sure what our stand had but it won best trade stand. For those that did not attend the Stafford show we don't sell parts over the weekend, for AN it about who we are and promoting classic Nortons to a wider and hopefully younger potential ownership and meeting some of our customers. We have planned and will plan to attend more shows this year and already looking ahead into 2024 which may involve a little more than just displaying, the main constraint being the amount weekends in the summer months it seems.

To answer other queries above, the comments above about tanks is interesting and something we have been looking closer at over the winter and now think we may have a couple of potential supliers. Front non disc front hubs. I searched the UK and the EU to find a foundry that could or would attempt to make them, then found a local foundry that believe they can do it. This will ensure that as hubs wear out in future or basket cases minus the hub will be catered for. For what was a part made in tens of thousands strangely it is now beyond foundrys due to casting in the brake track.
STS heads will be back in stock very soon, as collection is booked in to collect them.

thanks for the informative update!

That crank is too good looking to hide inside a casing.
Thank you to all for the pics and insight

I looked this over at the show & it is a very nice piece of machining. I did ask Ashley why they had incorporated a large sludge trap, seeing as how nearly every bike these days has a filter. He said they wanted to keep it as close to stock to suit all applications, which seems fair enough. It certainly would appear strong enough.

Matchless said:

I looked this over at the show & it is a very nice piece of machining. I did ask Ashley why they had incorporated a large sludge trap, seeing as how nearly every bike these days has a filter. He said they wanted to keep it as close to stock to suit all applications, which seems fair enough. It certainly would appear strong enough.

Click to expand...

Good question. I made a rough estimate of the volume and it's about 70 ccm. There are differing opinions as to how large the chamber needs to be. Crankshafts for cars don't possess oiling chambers, apart from the volume in the internal oilway, these will drain at a slow rate due to the bearing restrictors. Apart from serving as a sludge trap (for those who need this - imposing an external filter requirement would be quite reasonable!), the chamber provides an instand oiling reservoir, even if some of the oil might drain back if bike is left to sit for a long time (depending on crank position). As the Norton crank starts to turn, the centrifugal action caused by the throw creates a significant pressure rising with speed, typically 4-5 bar, so there will be no need for pump pressure, and this helps bridge those few seconds until the oil pump starts feeding the main bearings.
The oiling chamber also provides a certain grace time if oil supply is interrupted for whatever reason.

- Knut

Now in stock..

I am surprised how quickly AN is taking orders for cranks. Well done, AN and Arrow!

@Madnorton Did you do the Dyno test? I hope you will share some results in due course.

- Knut

@Madnorton Have you decided on producing a Mk3 version also? Hope you managed to conclude on its dimensions. I understand this version involves quite a bit of additional work for Arrow.

- Knut

As yet we have not built an engine, the workshop has a couple of dozen bikes waiting to be serviced / repaired, but it will be done. The MK3 drawings is nearing completion, but the unused NOS crank is nothing like the drawing we have for the MK3 crank, so its now looking like I will have to bite the bullet and strip one out of a spare engine I have. Once the drawing is validated we may park the manufacture of the MK3 cranks as this will be driven on manufacture costs as the lack of quantity may make them prohibitively expensive.

SteveA said:

I knew that Mick Hemmings had developed a crank before making his decision to retire. I thought it was with the support of Arrow, but I have no evidence for that.

I had also imagined that the effort would move to AN with other projects from Mick. But again, my imagination not stated fact.

So, I imagine what has happened is that in taking over a lot of stuff from Mick they also took on the crank. And what might they have been doing? Testing, productionising etc. I would imagine. Which all takes time.

I really doubt they are just gouging them out of lumps of metal and hoping for the best!

Click to expand...

Picture of the Mick Hemmings crank that was used in the engines of the Peter Williams Motorcycles monocoque replicas. Original plan was to build 25 but only 6 or 7 were actually built so there were a few available for sale.