Old bikes and oil leaks
Discussion
May seem a silly question. But why did old British bikes (up to and including the last Meriden Triumphs), leak oil while Japanese bikes and Hinckley Triumphs generally don't?
Was it looser manufacturing tolerances? Different engine construction methods? Or did old British manufacturers simply not give a damn?
Was it looser manufacturing tolerances? Different engine construction methods? Or did old British manufacturers simply not give a damn?
Some of it can be down to a lack of quality control but also a lot of it was due to the things having been designed decades earlier when nobody gave a damn about leaks or emissions. When a lot of the old Brit' 'bike engines were designed nobody would have ridden one expecting to stay clean and oil free. With so few vehicles about oil leaks presented less of a problem than horse s
t on the roads. The manufacturers were still using these basic designs up to the end, and in a lot of cases the same tooling and manufacturing techniques. Also a lot of the "leaks" were not actual leaks but breathers etc. that were not routed back to air filters or crankcases, again, because nobody cared about such things in the old days. By the dying days of the Brit' bike industry they were vainly trying to "retrofit" the idea of clean engines onto designs that even if meticulously put together still needed to vent externally (don't we all). Add in a workforce that couldn't be bothered, mangement that was near criminally incompetent and an almost complete lack of investment...
The Japanese designed a different product for a different market, horizontally split casings rather than vertical, breathers that fed back into the engine, tooling that wasn't thirty years old...
t on the roads. The manufacturers were still using these basic designs up to the end, and in a lot of cases the same tooling and manufacturing techniques. Also a lot of the "leaks" were not actual leaks but breathers etc. that were not routed back to air filters or crankcases, again, because nobody cared about such things in the old days. By the dying days of the Brit' bike industry they were vainly trying to "retrofit" the idea of clean engines onto designs that even if meticulously put together still needed to vent externally (don't we all). Add in a workforce that couldn't be bothered, mangement that was near criminally incompetent and an almost complete lack of investment...The Japanese designed a different product for a different market, horizontally split casings rather than vertical, breathers that fed back into the engine, tooling that wasn't thirty years old...
A huge contributing factor is that since the Japs came they brought horizontally split crankcases with integral gearboxes and the older Brit iron had vertically split cases, along with exposed primary drives, seperate gearboxes until around 1968 or so etc etc
The horizontal design has a larger contact area and has seals where parts exit such as alternators, ignition etc.The vertical just had "red hermetite" and hope.
The horizontal design has a larger contact area and has seals where parts exit such as alternators, ignition etc.The vertical just had "red hermetite" and hope.
Apart from the horizontal opposed to vertical split engine cases, other factors to take into account are age and technology of the components used in manufacture and assembly.
Many older bikes have been through many owners and as a result have had many years more abuse by the inexperienced make-do-and-mend home mechanic or the bodge-it brigade. Newer machines tend to go to the dealership for repairs as the components that are used are usually throw away items and not meant to be fixed but replaced.
Technology is in the manufacture of the components. The more modern engine have probably been designed and produced on a computer and with CNC machinery with the use of much better quality materials. The older machines had been produced using older designs and paterns for castings with lesser investment in technologyand manufacture. Many older machines are well past their original design life and were never invisaged to still be on the road 40 or 50 plus years later.
Many older bikes have been through many owners and as a result have had many years more abuse by the inexperienced make-do-and-mend home mechanic or the bodge-it brigade. Newer machines tend to go to the dealership for repairs as the components that are used are usually throw away items and not meant to be fixed but replaced.
Technology is in the manufacture of the components. The more modern engine have probably been designed and produced on a computer and with CNC machinery with the use of much better quality materials. The older machines had been produced using older designs and paterns for castings with lesser investment in technologyand manufacture. Many older machines are well past their original design life and were never invisaged to still be on the road 40 or 50 plus years later.
spoodler said:
...management that was near criminally incompetent and an almost complete lack of investment..
I'll say! When Meriden was closed, they were still using a machine that had a welded up crack in the casing. That crack was caused by a German bomb when the original Coventry factory was destroyed by the Luftwaffe in 1940. My favourite British bike industry story is what happened when Norton manufacture was moved from Birmingham to London. After the move they couldn't make a pair of Norton crankcases that would bolt up true, so they sent someone to see the Brummie who used to operate the machinery. "Have yow got the piece of wood?", he said. It turned out that the tool was so worn out that the only way they could drill the casting even half accurately was by jamming a lump of wood against the chuck to stop it wobbling around.
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