From big end bolts to conrods.
We are convinced- and our own experience with very reliable racing engines with a lot more power and torque than any standart production engines proves it- that our standard production Genuine Norton Factory Parts conrods (right) will stand all stresses they are likely to encounter in a Commando engine.
Other offerings are in the market. Steel conrods, heavy and asking for considerable re-balancing of the crank and therefore the answer to no question, and aluminium conrods machined from billet.
The billet conrods look "nicer" than ours, and look more substantial, too. This they are- in weight, 10grams to be exact- but not in strength. Furthermore, they have a lot more weight near the small end, where one does not want it. Original conrods are far lighter in this crucial area.
Our original conrods are made from forgings. A forging is far stronger than a piece of alumunium that is then machined to shape. As with the big end bolts above, whilst a part turned from billet may LOOK nicer, it is in fact far less equipped to take stresses than a forged part. It can only take the same stresses as a forged part if far more material is being used to make it and it is then substantially bigger and heavier than the forged part.
If no forged conrods were available to rebuild a Norton engine I might be tempted to use the billet one on the left and take it easy on the engine to compensate. However, as our forged rods are available, and have withstood up to 8.500rpm in a friend's racing Commando repeatedly, so are more than up to the job in any given Commando application, I use nothing else for road and race engines.
The rod failures I have seen in the last thirty years always had a basic technical reason- engine ran out of oil, rod was mechanically damaged when installed, wrong con rod bolts or re-used big end nuts and bolts. With an original conrod I have yet to see a failure caused by weakness of the rod itself.
I therefore use Genuine conrods in all my own Commando engines, road and race, and recommend to do as I do.