Saito FA-91S prop shaft thread?
01-30-2019, 05:05 PM
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Saito FA-91S prop shaft thread?
I have an older FA-91s that I bought on eBay a year or two ago. Was new in box never used. It came with a single prop nut, I have been looking to get a prop and jam nut assembly for it. The prop shaft thread is supposed to be 7 x 1 mm, however a 7 x 1 prop and jam nut I obtained from Horizon will not fit which in theory it should. An 8 mm nut is too big. I'm thinking the thread is a bit coarser, perhaps 1.2mm. Is a problem I didn't expect to encounter. Anybody else have any experience with an older FA-91S prop nut?
01-30-2019, 05:20 PM
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Yes I know the crank thread is supposed to be 7x1 mm, however I tried a 7x1mm nut at the local hobby shop and it will not fit my engine prop shaft. Threads seem too fine on a 7x1mm nut. Not sure why that is but my engine has a different sized prop shaft.
02-02-2019, 04:48 AM
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My bet is that these will fit: https://www.horizonhobby.com/prop-wa...eiijj-sai56135 And that the LHS guy tried the wrong nut.
02-11-2019, 09:42 AM
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I checked at a bolt supply house with a thread pitch gauge, the prop shaft threads are 7 x 1mm. I looked closely at the threads with a magnifying glass and the top thread seems to be a bit out of shape. The prop nut fits it ok but not the jam nut assembly which is a 7 x 1 mm thread. Going to chase the prop shaft threads with a 7 x 1 mm die and I expect that will fix the problem.
02-11-2019, 10:49 AM
#11
I checked at a bolt supply house with a thread pitch gauge, the prop shaft threads are 7 x 1mm. I looked closely at the threads with a magnifying glass and the top thread seems to be a bit out of shape. The prop nut fits it ok but not the jam nut assembly which is a 7 x 1 mm thread. Going to chase the prop shaft threads with a 7 x 1 mm die and I expect that will fix the problem.
