Worn driveshaft, how to tell

[peteSki]

Thanks to some great postings here, I was able to replace the strut bushings myself on my 97 Ski with GT-40. Used the drive shaft/strut bearing removal tool from Elbert's - worked great! I knew I had to change those bushings as there was considerable side to side movement when grabbing the prop and moving it side to side. I wasn't too sure that I needed to replace the drive shaft, but after I put everything back together and did an alignment, there is still some play in the strut bushings when grabbing the shaft where the prop goes on and moving it side to side.

My understanding is that there should be no play when the bushings are new, so I'm thinking my drive shaft is worn and needs to be replaced. Is this correct or will there always be a little play? Also, when I was doing the alignment, the coupler didn't line up perfectly with the transmission coupler initially, I had to lift the shaft slightly so the two would line up perfectly. At that point the only thing supporting the shaft was the strut bushings. Not sure if this is normal or not.

There are some wear marks on the shaft where the bushings rub, as well some wear at the coupler end where the seal would rub. This one you can actually see that the diameter of the shaft has been reduced with the naked eye. The shaft seal was also leaking more than it should, so I also installed a PSS shaft seal since I had everything apart.

I have not water tested, but the fact there is still play in the strut is a concern. There is less play with the new bushings, but still some nonetheless. I also get a rather loud vibration when I turn the shaft by hand. Not sure what would happen if it was turning fast under operating conditions, but again this is a concern.

I've attached a couple of pics and would appreciate some feedback on whether you think this drive shaft should be replaced. As far as I know it is the original one, and there is what appears to be a date stamp on the shaft indicating its from 04/10/97, but I don't know for sure that this in fact a date.

Regards,

Pete

[WakeSlayer]

Methinks you need a new shaft. You shouldn't have any play to speak of. The cutlass bearing is a water lubricated device, so if you are spinning it dry, couple with a bad wear groove, that would call the vibration. As far as having to lift the shaft a little to match the couplers up, that is normal. There is nothing holding the fore end of the shaft up. The shaft should be aligned from the strut forward. No More than .002" tolerance with a feeler gauge on the coupler, all the way around.

[SilentSeven]

Restarting this really old thread....Pete - do you recall how many hours were on the boat when you pulled the shaft? Did you ever replace it and what were the results? I'm considering doing the cutlass bearing on my 97 ski w/1600 hours and suspect my prop shaft may look like yours...

[peteSki]

Just looked up my maintenance log and confirmed I had about 1100 hours on the boat when I replaced the shaft. The main job was to replace the cutlass bearings but ended up doing the shaft as it was worn where it contacts the bearings. In the end I did new shaft, cutlass bearings, dripless shaft seal and a new prop. Also repacked the rudder seal as well. Made sure I did as best I could on the shaft alignment as well. I recall very well the results were AWESOME! The boat was so smooth, all the vibrations were gone and it really felt like a brand new machine!

My cutlass bearings were very stubborn to come out, I recall I got 1 out with the removal tool but then it became a bit of a hack job as the other just wouldn't slide out. Lots of patience and perseverance eventually got the second one out. Had the boat another 2 years before I sold it and never had any issues with it during that time.

[dhmcfadin]

I followed this video and it made replacing the cutlass bearing a breeze. Required no force whatsoever.

https://youtu.be/KsqOac-52Rs

I replaced the cutlass bearing, shaft (with an ARE double taper), and all packing both rudder and shaft log. Was able to align everything just under .002” boat runs smoother than it ever has since we bought it new. 1999 Sport Nautique with 4000+ hours. Not a hard job at all. Following that video and his other video about prop shaft alignment made the whole process really easy.

Here’s a pic of my cutlass bearing. Not pretty lol.