Is this a common break?

[Alessandro Garabaghi]

Friend Montley Crew Aquacraft snapped the flex shaft at I guess what is where the prop shaft is soldered on? Def didn't hit anything cause we drive in a really large lake no where near shore, and the boat just slowly came to a stop. Picked it up and no prop lol ...

[electric]

Can't say whether it is "common" to that boat as I do not own one, but it does happen. I would order a new one from Offshore here. A few things you should check though. Make sure you slide the shaft in lubed with grease and spin it with your fingers just to see if it turns freely and there is no binding. Also, you need to be sure there is a nice gap between the drive dog and the back of the shaft. The Drive Dog is the small piece that the prop goes up against. What can happen is as you hit the throttle the shaft "shrinks up" a bit due to the torque and can pull the spinning Drive Dog against the strut and then presto, bind up and snap.

I usually leave an 1/8" - 3/16" gap to allow for that. Some just say the gap should be equal to at least to the diameter of the shaft. Err on the side of caution and that should do it.

[Alessandro Garabaghi]

yea now that im thinking back i bet my friend cranked down his new bigger prop and caused the break

[TRUCKPULL]

The prop should tight to the drive dog.
The space should be between the drive dog and the strut.
When the wire wound shaft shrinks up you need the space, so that the drive dog does not pull tight up against the strut.
When this happens, the wound wire is pulled out of the prop shaft, = no prop shaft or prop.

Larry

[Capt'n Crash]

This was a common problem with the Aquacraft Revolt 30 drive shaft as well.
I was told by the dealer that sold me a Revolt that it wasn't a question of weather or not the shaft would break, but when. I suspect the Montley Crew drive shaft has the same issue.
I've since upgraded all my drive shafts with the one's available here on OSE and never had an issue.

[Alessandro Garabaghi]

cool i will let him know.

[slider46]

Also common on the UL1 hydro Aquacraft has a problem with the flex drives they sell....