double speed oil pump worm drives (2016)
- Thread starter fireflake
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The 6 start oil pump worm drive was a absolutely must have 'go faster' modification of my youth amoung we youngsters who knew nothing about either motorcycle Engineering or our Norton Dominator motorcycles.
As far as I have managed to determine it was introduced by Mr Doug Hele to increase engine oil flow on his Domiracer engines because he had incorporated positive pressure fed lubrication to the cam lobes to ensure the cam and followers were CORRECTLY lubricated and this of course required a greater flow rate from the pump. A Gentleman who worked on the Domirace project with Mr Hele conformed this to be fact. I would guess wider pump gears to increase flow would of required a wider pump body which would of required a major? redesign so it was a LOT quicker and cheaper to simply double the pump speed ?
I did hear from a friend who was 'into' Triumphs that at one time Triumph incorporated into the 3s a timed oil supply to the cams / followers which apparently was quickly removed as it was found to reduce oil flow to the rest of the motor! If so clearly a lot of testing was done before incorporating it into production. Slumberglade Hall again?
My very old memory banks tell me that the original oil pump designed for a 500 twin with its smaller big ends had the width of the gears increased for the 650 motors but that for his race motors Mr Dunstall used old oil pumps with the smaller input gears and modified the body to incorporate the larger return gears.Wonder if he used 3 or 6 start drive gears?? Someone must have the Doug Hele Domirace motors and be able to give us facts....last time I saw one of the motors it was in Mr Dunstalls office and he wanted £200 for it. I was earning £12 a week at the time.....
Personally I do not believe that you can take anything and double its speed without ramifications occuring unless the device was originally designed with this in mind but at the end of the day the Commando system appears to work well providing owners keep some oil in the tank!! Mind you when I hear of the number of new oil pumps being manufactured and sold either the pumps are wearing out badly OR as I and others in the trade suspect owners are unaware that gear pumps will always pass oil back into the cases and if they did not do so the gears would have no clearance in the bodies and not turn. A friend does the modification to owners timing covers to incorporate the later anti drain system which as he says ..if it fails it will fail safe still allowing oil to the engine.
Wonder if the Norton drawing for the oil pump gears show the changes made to them? The drawing I received yesterday for the rotary clutch pressure plate does and now I understand how they managed to get the clutch to sort of free off with its 18 friction interfaces. It is good to know that bodgery lasted to the very end. Did Brunel bodge thing ?
As far as I have managed to determine it was introduced by Mr Doug Hele to increase engine oil flow on his Domiracer engines because he had incorporated positive pressure fed lubrication to the cam lobes to ensure the cam and followers were CORRECTLY lubricated and this of course required a greater flow rate from the pump. A Gentleman who worked on the Domirace project with Mr Hele conformed this to be fact. I would guess wider pump gears to increase flow would of required a wider pump body which would of required a major? redesign so it was a LOT quicker and cheaper to simply double the pump speed ?
I did hear from a friend who was 'into' Triumphs that at one time Triumph incorporated into the 3s a timed oil supply to the cams / followers which apparently was quickly removed as it was found to reduce oil flow to the rest of the motor! If so clearly a lot of testing was done before incorporating it into production. Slumberglade Hall again?
My very old memory banks tell me that the original oil pump designed for a 500 twin with its smaller big ends had the width of the gears increased for the 650 motors but that for his race motors Mr Dunstall used old oil pumps with the smaller input gears and modified the body to incorporate the larger return gears.Wonder if he used 3 or 6 start drive gears?? Someone must have the Doug Hele Domirace motors and be able to give us facts....last time I saw one of the motors it was in Mr Dunstalls office and he wanted £200 for it. I was earning £12 a week at the time.....
Personally I do not believe that you can take anything and double its speed without ramifications occuring unless the device was originally designed with this in mind but at the end of the day the Commando system appears to work well providing owners keep some oil in the tank!! Mind you when I hear of the number of new oil pumps being manufactured and sold either the pumps are wearing out badly OR as I and others in the trade suspect owners are unaware that gear pumps will always pass oil back into the cases and if they did not do so the gears would have no clearance in the bodies and not turn. A friend does the modification to owners timing covers to incorporate the later anti drain system which as he says ..if it fails it will fail safe still allowing oil to the engine.
Wonder if the Norton drawing for the oil pump gears show the changes made to them? The drawing I received yesterday for the rotary clutch pressure plate does and now I understand how they managed to get the clutch to sort of free off with its 18 friction interfaces. It is good to know that bodgery lasted to the very end. Did Brunel bodge thing ?
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J. M. Leadbeater said:
:roll: :roll: :roll:
The triples' timed tappet feed was found to be somewhat unnecessary and was eventually deleted but only after the triples had been in production for three years so was not the big drama you make it out to be.
This apparently occurred around late '71 as the timed tappet feed parts are in the '72 parts book but "not required on later models" so not "quickly" even by BSA/Triumph standards.
http://bigdcycle.com/tempbooks/tri/triple/1972.pdf
Timed tappets had already been in use on Triumph 650 twins beforehand and very likely too early for Umberslade Hall to have had any influence on the triples' timed tappet feed design.
texasSlick
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FWIW: Dunno why, but my 1963 Atlas (actually birthed from the factory May 21, 1962) came factory stock with a six start pump. I suppose it was some sort of special build ... there are several other anomalies about the bike that would suggest so.
Slick
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Fitted a set of 6 starts to my 99, caused all sorts of issues,gone back to 3 start, and the orriginal std crank is still working 58 years old. Apparently the centrifuge action sucks the oil through faster than even a 6 start can push it.
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