Has the life of roller bearings for crankshafts [both main and conrod] gained in lifespan due to more modern and durable materials being available ?

For sure. Not only the physical and chemicals properties of the steels had improved, but also the accuracy of production methods and tolerances. And not to forget the lube oils.

No, but Conway was wrong when he estimated crank life as only 10K miles.
Materials have not changed. Molsheim used already a very good case hardening steel that was equal to current available steels.
Molsheim tolerances can hardly be beaten either. It is amazing to notice the tolerances Molsheim could achieve with non NC machines.
Oils might have improved, not so much the lubricating properties but in the sense that modern oil will keep the oil ways in the crank cleaner. Oil starvation is one of the main reasons for crank failure.
In the past roller cranks got a bad name because bronze cages used in the early days would crack due to aging. In later days Molsheim used Dural cages with less rollers as does everyone today. Modern caged needles are the best way to restore a Molsheim crank with worn roller tracks.
Bugwrench

It is strange how some people think that CNC machines improve tolerances; this is just a matter of good, high stiffness manufacturing machines and high quality cutting tools. Once you have that, attaining good tolerances is only a matter of time and good workmanship.

CNC machines only work cheaper in today's world where labour is made extremely expensive.

Another question: I once heard that the Royale was so expensive because it was built to a tolerance level of zero; It was machined as accurate as the accuracy of the measuring tools. Can anybody confirm or deny?

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today the material for this bearings is 100 cr 6 . The uniform quality is much better today .The possibilities for analysis of steel for the quality control is much better. electronically controlled hardening process is much better .The production of rollers and needles , electronically measured . is much better . You can not compare a bearing from 1930 with one from today . Go to a company who make them , and have a look how it is made today .

I have the memoirs of a molsheim mechanic who, as an apprentice, was given a crate of railcar camshafts to repair.He had to pick out the best halfs,then file or grind the worst damage off the lobes then assemble the half camshafts back together.This does not sound very precise to me.

This statement would have been correct if written in the 60's or 70's, when detergent and dispersant additives had been widely introduced. In the 50 years to follow further considerable improvements had been made, the base oils today are MUCH better (e.g. sulphur reduced from more than 1 % to only a few ppm), but also the additives. Today lube oil contains up to 10 different additive components for numerous targets and applications, of which the detergent is only one. Problems of the past had been also molecule destruction (e.g. by the interactive movement of the rollers), and corrosion of metal surfaces by sulphur and other ingredients.

Still in the 60's Mercedes customers had been gifted with a watch if they performed 100.000 km with the first engine, today an engine failure at that number would be reason for a guarantee claim. No doubt that Bugattis in their era had been excellent pieces of premium craftmanship, but times have changed. For sure!

The Royale was built to the same tolerences as any other Bugatti I'm afraid.

I had enough Bugatti engines and other parts in my workshop . The Bugatti quality is a myth . The quality is compare to other companys very low . Especially the aluminium castings have so much porosity , I did not see castings like this before .

In my 55 years of Bugatti experience I have yet to see a porous casting. That is why I suggest to the BB readers to not take this statement of Mr. Udolahr too serious.
In the mean time he has become a well known Bugatti basher so we know what we can expect from him but nevertheless I see it as my duty to counter his unproven statements that otherwise might be taken serious by the not so experienced BB reader.
Bugwrench

The Molsheim Bugatti People told me first about this porosity problem . ( I do not like to show names , but this people are well known ) . I tried to weld new finns to a t37 sump and was amazed how much oil was in the aluminium .
Burwrench , I life in the real world and not in some fantasy Bugatti world .I have to run 3 companies and if I start to move into the dream world of Bugatti quality I can close them .

And now Udolahr suggests that bad welding properties of 85 year old castings due to the fact that they have been soaked in oil during 85 years is enough proof that the Bugatti castings are porous. Please confirm you have made a scientific comparison between the welding properties of 85 year old oil soaked Mercedes castings and Bugatti castings before you made this blunt statement.
BTW TIG welding of oil soaked castings is an art, you should practise a bit more, I know what I am talking about!
Bugwrench

most time we weld Anzani crankcases from 1909 are crankcases like this . Most time bevore 1918 .
You know what you talking about ! Why , I never did see anything you made . What is your company name ? How many engines did you build ? What kind of crankcases did you weld ?Only Bugatti ? Who are you , only a forum talker ?

Topic locked due to not following forum rules.