Re: Birth of a kit
Post by Sticky » Thu Dec 15, 2016 7:22 pm
Warkton Tornado No.1 wrote:
The basic design of the rear hub supported on the lay-shaft is the cantilever principle as used on V*spa front & rear hubs as well as virtually all cars.
I have no doubt that adding a supplementary support would help but whilst there are other problems that have been indicated by some really well informed responses given recently; I think adding a supplementary support is only masking the problems.
The reaction given by Nudger is not based on my gut reaction, or anybody else’s, for that matter. He has enabled a logical, methodical approach using known techniques that enable us to make sound judgements.
For now, to achieve ultimate ‘peace of mind’ the best, most practical solution may be a non destructive test of any lay-shaft likely to be used, including any ‘super-duper-bling-looking-yet-not-certified’ replacement lay-shafts that some would have us queuing up to buy!
Couldn't be arsed in a long forum answer to all your digs, so I wrote a long article instead.
http://www.scooterlab.uk/fixing-weak-links-opinion/
I’ve been designing components for the best part of forty years in various industries.
The ‘safety critical’ sectors where certification is carried out have included Defence, Motor Sport, Automotive & the Lift Industry.
Inspection of components to ensure they conform to the Designer’s remit is something that has to be carried out, regardless of whether that industry is self regulating or not.
I would have read your article in any case, despite your provocation.
In it, you mention the failure of lay-shafts experienced by Innocenti. You don’t state how they worked to resolve the problem, but almost certainly they did & their efforts would have undoubtedly been recorded & the engineering drawings modified accordingly.
Thus, everything associated with the manufacture of OEM lay-shafts will have come about as a logical process of evolution.
Of the ‘many’ failures you mention again in your article, you have no absolute evidence as to why they have failed. You talk about ‘the thread’ but that will not have been the reason for failure. Perhaps you elude to the undercut, but there is a common misconception that they weaken components, whereas applied correctly, they effectively strengthen parts by relieving stress.
Thankfully, other Forum members are being constructive & there has been some analysis of the broken lay-shafts that have been made available.
Yet, before any evidence for the reasons of failure can be presented, you publish details of a new alternative to OEM lay-shafts. As is your right to do so.
The fact that you consider it to be superior can be in no doubt.
My own opinion (if I’m allowed one..) is that it
ought to be superior.
Yet, how does either of us know?
Do you know details of the material? Do you know how many stages are involved in the forging of it? Do you know by what means the spline & thread has been produced? What thread undercut has been utilised? What heat treatments are used throughout the manufacture? What inspection methods have been utilised? How many stages are involved in Inspection?
I don’t care that my opinion may not be popular with you, or anybody else for that matter.
Just because I am prepared to say, effectively:
“The new, special lay-shaft looks purposeful but how can we be certain it is any better than the OEM components it aims to succeed?”meets with your disapproval & consequently your attempts to vilify me for stating my opinion on a Member’s Forum.
