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Tacho drive mount

Ray Bear

Forum Website User
Non-VOC Member
Hi again everyone, and as is obvious by my two prior posts I am mounting a tacho to my 47 rapide, however I am more than curious as to why the tacho drive was not mounted to the end of the ATD,as it would not be difficult to spark erode a female drive in the end of the ATD mount stud without weakining it and shim the drive out some 25 thou which wouldnt look out of place .. Does the drag of the cable have effect on the advance curve of the ATD or is it the genuine parts are available for a manual advance magneto setup and thats the easy way out. I like my Roy Price ATD and its staying,(I think) also my prior thread of mounting off the dynamo may not be the best due to dynamos high rpms affecting longetivity of mechanisims.(thanks for all replies).
I spend my life working in the mechanical & engineering trade and some things seem so obvious and yet arent done so there must be some obvious thing or reason that my well faddled and tattered out old brain hasnt picked up..Hope some one has the correct answer to save me finding out the hard way..Thanks for all replies. Bill :confused:
 

mercurycrest

Well Known and Active Forum Website User
VOC Member
On my Bonneville bike, I drilled a 1/4"X20 threaded hole in the center of the ATD stud, then made a bolt with a slot that matched the tack drive. I may have had to shorten the drive tab (can't remember), in any event, it all seemed to work just fine, not that I did that much pottering around at 2,500RPM.
Cheers, John
 

Hugo Myatt

Well Known and Active Forum Website User
VOC Member
Hi again everyone, and as is obvious by my two prior posts I am mounting a tacho to my 47 rapide, however I am more than curious as to why the tacho drive was not mounted to the end of the ATD,as it would not be difficult to spark erode a female drive in the end of the ATD mount stud without weakining it and shim the drive out some 25 thou which wouldnt look out of place .. Does the drag of the cable have effect on the advance curve of the ATD or is it the genuine parts are available for a manual advance magneto setup and thats the easy way out. I like my Roy Price ATD and its staying,(I think) also my prior thread of mounting off the dynamo may not be the best due to dynamos high rpms affecting longetivity of mechanisims.(thanks for all replies).
I spend my life working in the mechanical & engineering trade and some things seem so obvious and yet arent done so there must be some obvious thing or reason that my well faddled and tattered out old brain hasnt picked up..Hope some one has the correct answer to save me finding out the hard way..Thanks for all replies. Bill :confused:

Found it! Forty Years On page 250, sections 9 & 11 for rev counter drive from dynamo and page 265 section 49 for atd drive. Only book learning on my part.
 

clevtrev

Well Known and Active Forum Website User
VOC Member
Hi again everyone, and as is obvious by my two prior posts I am mounting a tacho to my 47 rapide, however I am more than curious as to why the tacho drive was not mounted to the end of the ATD,as it would not be difficult to spark erode a female drive in the end of the ATD mount stud without weakining it and shim the drive out some 25 thou which wouldnt look out of place .. Does the drag of the cable have effect on the advance curve of the ATD or is it the genuine parts are available for a manual advance magneto setup and thats the easy way out. I like my Roy Price ATD and its staying,(I think) also my prior thread of mounting off the dynamo may not be the best due to dynamos high rpms affecting longetivity of mechanisims.(thanks for all replies).
I spend my life working in the mechanical & engineering trade and some things seem so obvious and yet arent done so there must be some obvious thing or reason that my well faddled and tattered out old brain hasnt picked up..Hope some one has the correct answer to save me finding out the hard way..Thanks for all replies. Bill :confused:
I don`t recall any spark erosion machines in those days when the factory was active.
 
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