Modern machining

[Brian]

Occasionally the subject comes up about the quality of the BSA tooling and the subsequent quality of the products they produced in the last few years of production.

Its often said had BSA upgraded their machinery they may have been able to producer higher quality products and may have stayed in business.

Now the thing is modern motorcycles are produced with the latest machinery, CNC etc etc so quality should be perfect.

I fit rod kits for people and I have added some pictures of the little end of a rod I removed from a modern 450cc KTM. Maybe our old BSA's were not so bad after all ?

[limeyrob]

Having owned BSAs from the 50's 60's and (early) 70's I would say the late 50's early 60's are best.  The designs are good, they have sorted suspension and handling, brakes are getting better and there's no obvious cutting corners or cost saving. Materials are high quality, they are making money and building products to last.  There was some obvious cost cutting on the 71 A65, not drastic, but poor finish on fasteners and poor details.  Parts cracked and broke on the A65, something unimaginable on a 50's A10.
BSA were always an arms manufacturer and I think one thing they could do was make a lot of identical parts very accurately.

[Rex]

I tend to agree.
Those interminable bores who like to crap on about "how crap those old Brits(sic) were et cetc" usually have only ever ridden modern Asian bikes and whose technical expertise runs to checking the tyre pressures, but hey, they've read all about the Sad Demise in Classic Bike and on the Net so it must be true.

[muskrat]

G'day Brian.
Very poor quality control there. Makes you wonder how many got through like that.
Cheers

[Bsareg]

I have a goldie rod machined like that. I bought it new from a dealer but I think it probaly came from the reject bin. Needless to say the dealer supplied another, but I kept the dodgy one.......

[berger]

the main thing is where it looks horrible to the eye doesn't matter , the finish in the EYE is what matters , and apart from that i am more worried about the ferrous  materials used to build things nowadays, weather it's girders or fixings, they all seem to be scrap before they are used for a job, but it keeps the money going round. i often look at some 80+ year old nuts and bolts in my collection and then look at some new metric bolts and nuts , then put the nuts on and see how crap the thread form mating is on the new stuff, also the quality of material used. an old 80 year old screw fixed in a piece of wood for 20 years will not snap it's head off when getting it out , a modern day screw only has to look a fog for a second and it will break its head off. so it's not so much about modern machining.  it's about what will do for the job  with the cheapest methods to produce the quickest result.

[Black Sheep]

Engineering is all about producing a product as cheaply as possible to meet the spec. There's a poem called 'The one horse shay' about a horse cart which, on reaching 100 years old, turns instantly to dust. Perfect engineering!   

[Colsbeeza]

Brian, I wonder if they deliberately lengthened the stroke by moving the small end hole. It does not look like an accident. Perhaps their blank rods were a bit short. Hopefully as most of the load on the rods is on compression they won't fall apart. Nevertheless I wouldn't like it.

[muskrat]

G'day Col.
Things like that happen. If a casting/forging is a little odd and the clamping in the machining jig is off due to this.
I saw it often when machining gearbox castings for elevators (I'd rather take the stairs).
The picture reminds me of when I made eccentric little end bushes to up the compression in the racer 
Cheers

[limeyrob]

I often see people taking out 1950 / 60's plated steel bolts and putting in stainless metric then wondering why they break after a year or two.  Unfortunately its not just metric, I recently needed some High Tensile BSF bolts for a diff.  The new bolts failed before they got to the torque - junk.  I found some 1950's old stock, tested one and it was fine at 20% over torque.  I did some sums and checked up on the specs.  The R rating is very wide. the new bolts were right on the bottom allowed, and the old bolts were right at the top.  Says it all.  1950 - we'll make the best we can, 2024 how cheap can we make it?

[jhg1958]

and apart from that i am more worried about the ferrous  materials used to build things nowadays, weather it's girders or fixings, they all seem to be scrap before they are used for a job, but it keeps the money going round. i often look at some 80+ year old nuts and bolts in my collection and then look at some new metric bolts and nuts , then put the nuts on and see how crap the thread form mating is on the new stuff, also the quality of material used. an old 80 year old screw fixed in a piece of wood for 20 years will not snap it's head off when getting it out , a modern day screw only has to look a fog for a second and it will break its head off. so it's not so much about modern machining.  it's about what will do for the job  with the cheapest methods to produce the quickest result.

Not sure I agree wholeheartedly. I was involved a little with NDT for the nuclear industry. The quality of metal produced now is significantly better than 50 years ago. In the past because the presence of defects items were built with large safety margins built in the design. As the materials improved the safety margins were reduced.

If you think about this old kit built with a large safety margin probably has not failed because it was lucky not to contain a defect. These items will be stronger than new items built smaller but with the confidence it will contain less defects.

Does that make sense?

John

[Rex]

  The new bolts failed before they got to the torque - junk.  I found some 1950's old stock, tested one and it was fine at 20% over torque. 

One reason why I'm very unwilling to fit repro big end bolts. I'll take my chances (within reason) with used bolts than risk some Taiwan sweatshop repro shite of unknown metallurgy.

[Triton Thrasher]

Brian, I wonder if they deliberately lengthened the stroke by moving the small end hole. It does not look like an accident. Perhaps their blank rods were a bit short. Hopefully as most of the load on the rods is on compression they won't fall apart. Nevertheless I wouldn't like it.

Moving the small end hole does not increase the stroke.

[Colsbeeza]

You are right of course TT. Took me a few seconds to realise that. Depends entirely on the crankpin centre distance to crankshaft axis.
Col