Nodular cranks.

[teebee67]

Hi all. This has probably been asked before but I can't find a certain answer using the search function. Can anyone tell me for sure when Nodular cranks were first fitted. I have seen many answers from 1959 to 1963. Also when did they change from Dynamo to Alternators, I have a 1959 alternator engine but have seen 1961 bikes with dynamos.

[dave16mct]

The singles changed in 1958 for road models. The twins didn't really change as such. From 1959 there was a standard twin with alternator and a deluxe twin with mag and dynamo (also had chrome tank panels). Not certain but I think nodular cranks came in 1962.
Dave.

[SPRIDDLER]

There is a thread on this subject from 4 weeks ago, here...…..

http://www.jampot.com/forum/viewtopic.p ... ar#p217829

[dave16mct]

Looking through the old jampot magazines on here, (thanks Rob H,) An interview with former factory employee Harry Wynch. He states that in a meeting after reports of cranks breakages, it was decided not to use nodular iron for the sake of the extra cost. He says the extra cost was 9d (about 4 pence!).
Dave.

[gotoole]

What is the difference between nodular iron and steel? Is it to do with carbon content or the way it is made?

[teebee67]

There is a thread on this subject from 4 weeks ago, here...…..

http://www.jampot.com/forum/viewtopic.p ... ar#p217829

Thanks spriddler but, as I said, I have looked at other threads on here (including that one) but none of them state when nodular cranks were first fitted. That is what I would like to know, unless there isn't a definitive answer?

[dave16mct]

Go to Tech Articles (above). Select Twin changes and you will find the answer.
Dave.

[Mick D]

What is the difference between nodular iron and steel? Is it to do with carbon content or the way it is made?

Hi

'Nodular' refers to the shape of the graphite content of cast iron - in basic cast iron they are flakes, in nodular they are spheroid, (nodular).

Nodular graphite reduces the internal stresses in cast iron and results in a higher resistance to cracking.

Regards Mick

[JEAN-NOEL]

Hi Tony,
I have'nt found the answer...
Ernie Merriweather said the crankshaft has been improved, but without indicating a date or an engine number".
Roy Bacon wrote "From about 1960 its material was uprated for a high grade alloy iron casting to nodular iron..." No more date or engine number
If it is original your '59 engine has a "mehanite" crankshaft, not a "nodular" one.

[SPRIDDLER]

Can anyone tell me for sure when Nodular cranks were first fitted. I have seen many answers from 1959 to 1963.

This is all I've found (and you have probably seen that as well) in Tech articles for the nodular crank in 1962. No engine numbers given. Broken cranks may have been replaced over time with nodular but the 'tapping and ring' test isn't any help when the c/shaft is in situ.

Nodular.JPG