View Full Version : Drive Shaft Coupler

10-05-2012, 12:02 AM
Anyone ever had your driveshaft slide off the transmission? My 2008 X14 DID! I have a hundred hour on the boat and was out for a ski last week, when the driver throttled up to pull me, it was like the boat was in neutral. After getting my ski off and into the boat to figure out the shaft had worked its way off the coupler! As it turns out there is one nut that holds the drive shaft to the coupler, it failed. My Dealer tells me this a common problem, 5 or 6 this summer!

10-05-2012, 12:07 AM
Why can't you put the nut back on yourself and get back on the water? Should be 1", 1 1/8" or 1 1/4"

88 PS190
10-05-2012, 12:14 AM
Its inside the coupler right? don't you just loosen 4 nuts and bolts, then attach the nut reattach the coupler?

10-05-2012, 01:31 AM
It is in the coupler, I can put it back on myself. But whats going to stop it from happening again.. Dealer says they use lock tight to fix, but the shaft is stainless steel and you can't put lock tight on stainless. My whole point is Mastercraft designed this they should fix it with a cotter pin or other failsafe measures and recall the rest. Heads up for others to take apart your coupler and check the nut.

10-05-2012, 08:10 AM
See if you can get a nylock nut in the correct size, maybe from Fastenal.

10-05-2012, 12:01 PM
Nothing tighter than a good cross-thread.:rolleyes:

Seriously I would go with a nylock nut.

10-05-2012, 12:51 PM
Some of the shafts have a hole for a cotter key style nut but if no cotter key hole, the nut should be a nylon lock style nut. At least one other guy on here has the same issue. http://mastercraft.com/teamtalk/showthread.php?t=48539

10-05-2012, 01:10 PM
If there iroom add a second nut with a lock washer to the origonal config.

10-05-2012, 01:18 PM
Nylon type lock nut sounds like the answer. Could always punch the thread delicately after putting the nut on. Just wondering what direction the shaft is turning and whether this should have been a left hand thread maybe so as to self tighten.

10-05-2012, 01:21 PM
One nut? a picture would be great...

10-05-2012, 01:31 PM
One nut? a picture would be great...

Don't make him drop his pants now.:D

10-05-2012, 02:31 PM
To my understanding those nuts are torqued so tight they shouldn't ever come off. Only time I've heard of this happening was on an older boat but there was a slight vibration in the shaft due to hitting a rock or something. Over time the vibration was able to work the nut loose but didn't come all the way off.. Driver could feel the slop in the shaft and noticed the shaft had play. In your case you can put other things besides locktite on the shaft. Try getting some Type X or Jbweld... take a wire brush to the threads and scrub till course then make it last for ever. Shafts come with a new coupler, so if you ever replaced it it doesn't need to come off anyway. I know this sadly. lol

10-05-2012, 08:37 PM
I imagined the original post was referring to the half coupling that is on the transmission output shaft rather than the prop shaft?

10-06-2012, 01:18 AM
I imagined the original post was referring to the half coupling that is on the transmission output shaft rather than the prop shaft?

It was the prop shaft on previous report. Not sure what happened to his pics... but same thing no power and discovered the prop/shaft was being held in by rudder, scary if that some how happens under power, it could cause some serious damage.