Tightening prop adaptor with motor in a cowl

[Steve_Wright]

So the prop adaptors that clamp up with the prop nut being tightened, how to you do them up what you cannot hold the motor body to stop the prop adaptor spinning on the motor shaft? The cowl on my P-51 doesn't give you access to hold the motor at all.

 

Ta

Edited June 18, 2021 by Steve_Wright

[Allan Bennett]

Good question!  I have no particular method, but I find that usually once the nut gets reasonably tight the friction between the prop and the prop-driver is enough to allow me to finish the tightening by holding the prop.  So far I haven't needed to try it, but maybe a disc of sandpaper glued to the face of the prop driver would help if it's too smooth to grip the prop.

[Ron Gray]

Sandpaper disc definitely the way to go.

[Steve_Wright]

its the adaptor spinning on the motor shaft, its one of those wedge adaptors. Wondering if roughing the shaft slightly would help?

[Steve_Wright]

Actually, see what you mean now, will go and try.

[Frank Skilbeck]

Yep, some motors have a hole drilled in the end of the prop adaptor so you can put a small bar through to hold it while you tighten the propnut, I wish more did this.

[Steve_Wright]

scuffed all mating surfaces with some emery and managed to get enough friction to get everything tight ?

[Glasshopper]

try cutting a slot big enough for a screwdriver blade in the end of the adapter so that the screwdriver can hold the adapter whilst the lock nut is tightened.

[Simon Chaddock]

Steve

The correct prop adapter on the correct shaft should be a 'positive' fit in other words it should require a definite push to get in on the motor shaft. Like that it will not turn when just holding the prop. Indeed when tightened it can create an interference fit on the motor shaft that can make it difficult to get it off.

If the adaptor has slipped on the motor shaft under load at any time it will wear a tiny bit and loose the correct fit. If an adapter is not a positive fit it should be replaced.