backlash

sixpack

Forum User
Non-VOC Member
good day to all---currently replacing the drive gear for the KVFTTmag on my 1950 rapide----the new gear shows 17/18 thou backlash----is this an acceptable tolerance????---are there oversize gears available???? ---many thanks for your time
 

chankly bore

Well Known and Active Forum User
Non-VOC Member
This gear is meant to have backlash- it stops the magneto bearing being overstressed and the gear is "loaded"- for want of a better term, by magnetic resistance (one hopes) at the point of firing, at least by a conventional magneto. Only points to watch are that timing is done with this in mind and that the teeth, A.T.D., and springs are in good fettle. There never were oversize gears for the foregoing reasons. There were however nasty nylon gears some years back, and they caused a lot of grief because they GREW. I assume sixpack refers to brewers' wares as no fit young person should be seen near one of our old gaspers. Cheers.
 

roy the mechanic

Well Known and Active Forum User
VOC Member
I remember reading somewhere that the backlash is intended as the tufnol mag pinion expands when it gets hot. As in the words of the prophet-panic not!
 
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