79 SN drive shaft detached from coupler

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   Hello All!

Earlier this summer I purchased my very first boat, a beautiful 1979 Ski Nautique. I am on this forum every week trying to learn all the ins and outs of the boat, and the posts have been extremely helpful.

Last week however I ran into a problem I couldn't find anywhere on the forum. We were out on the lake and my buddy ripped the throttle from full open to idle to slow down quickly as we headed into shore, and we suddenly lost all thrust and the boat yawed hard left, taking on a small amount of water. We open the engine cover to discover the drive shaft came completely out of the coupler. Luckily the rudder caught the shaft before it could exit the boat. Here is a picture.

I've seen many posts about the coupler being too difficult to remove, but never this. I don't think I have the equipment or experience to successfully install an interference coupler onto my single taper drive shaft, so I think my best option is to buy a new ARE double taper drive shaft and coupler.

This process uncovered three more problems though, which can be seen in the next picture.

The drive shaft coupler is stuck to the transmission coupler. I removed the bolts and gave it a couple of light taps with a mallet, and tried separating them with a flathead screwdriver, but I can't get them separated. I'm afraid to go wailing on the thing because I hear transmissions are surprisingly fragile.
It looks like I have an alignment issue. As far as I can tell my driveshaft is straight, and my cutlass too, and I am worried that it is the engine that is not aligned correctly. The previous owner said that this is the boat's second engine, so it could have been installed incorrectly. Is this something I can correct myself?
While I am replacing the coupler should I consider replacing the transmission too? I don't know how to tell whether its time for a new transmission.
Thanks in advance! This forum is really invaluable to a new boat owner like me.
-John

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john_sn Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: August-02-2021 Location: Meridian, MS Status: Offline Points: 27	Post Options Post Reply Quote john_sn Report Post Thanks(0) Quote Reply Topic: 79 SN drive shaft detached from coupler Posted: August-05-2021 at 3:15pm
	Hello All! Earlier this summer I purchased my very first boat, a beautiful 1979 Ski Nautique. I am on this forum every week trying to learn all the ins and outs of the boat, and the posts have been extremely helpful. Last week however I ran into a problem I couldn't find anywhere on the forum. We were out on the lake and my buddy ripped the throttle from full open to idle to slow down quickly as we headed into shore, and we suddenly lost all thrust and the boat yawed hard left, taking on a small amount of water. We open the engine cover to discover the drive shaft came completely out of the coupler. Luckily the rudder caught the shaft before it could exit the boat. Here is a picture. I've seen many posts about the coupler being too difficult to remove, but never this. I don't think I have the equipment or experience to successfully install an interference coupler onto my single taper drive shaft, so I think my best option is to buy a new ARE double taper drive shaft and coupler. This process uncovered three more problems though, which can be seen in the next picture. The drive shaft coupler is stuck to the transmission coupler. I removed the bolts and gave it a couple of light taps with a mallet, and tried separating them with a flathead screwdriver, but I can't get them separated. I'm afraid to go wailing on the thing because I hear transmissions are surprisingly fragile. It looks like I have an alignment issue. As far as I can tell my driveshaft is straight, and my cutlass too, and I am worried that it is the engine that is not aligned correctly. The previous owner said that this is the boat's second engine, so it could have been installed incorrectly. Is this something I can correct myself? While I am replacing the coupler should I consider replacing the transmission too? I don't know how to tell whether its time for a new transmission. Thanks in advance! This forum is really invaluable to a new boat owner like me. -John

Gary S Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096	Post Options Post Reply Quote Gary S Report Post Thanks(0) Quote Reply Posted: August-05-2021 at 3:40pm
	Sit back and be very thankful, you could have ripped the strut and rudder right off the bottom of the boat. When you go to put this all back together get yourself a safety collar so it never happens again. Here is the video for shaft and engine alignment- https://www.youtube.com/watch?v=3_w0LvD6gEc Coupler is just frozen in place,might have to take a couple of heavy hammers- place one on one side of the rearmost coupler halfs and start tapping across from that to break that rust bond. I would wait and see with the trans,it's probably ok
	69 Mustang HM SS 95 Nautique Super Sport

Jonny Quest Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2995	Post Options Post Reply Quote Jonny Quest Report Post Thanks(0) Quote Reply Posted: August-05-2021 at 4:35pm
	Dodged a bullet, for sure. I agree with the ARE shaft option. Good way to go. Also, General Propeller in Bradenton, FL sells double taper shafts. Use a safety / retaining collar with the new shaft. If that shaft completely exits the boat, there is a big hole for water to come in and ruin your day even more… JQ
	Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum

SNobsessed Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: October-21-2007 Location: IA Status: Offline Points: 7102	Post Options Post Reply Quote SNobsessed Report Post Thanks(0) Quote Reply Posted: August-05-2021 at 4:46pm
	For the stuck coupler, you could try some penetrating fluid. A homemade version is auto trans fluid (any brand) & acetone, 50/50. Apply several times over several days. Works wonders.
	“Beer is proof that God loves us and wants us to be happy.” Ben Franklin

8122pbrainard Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045	Post Options Post Reply Quote 8122pbrainard Report Post Thanks(0) Quote Reply Posted: August-05-2021 at 5:00pm
	John, Welcome to CCfan. Glad you found us. Plus one on the double taper prop shaft. It will speed up the installation. FYI, you lost the shaft out of the coupling due to misalignment which caused the shaft to coupling fit failure due to fretting. When you get the new shaft, pay very close attention to alignment. Keep in mind alignment starts at the strut. I suspect the strut is misaligned or maybe bent.
	54 Atom 77 Tique 64 X55 Dunphy Keep it original, Pete <

john_sn Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: August-02-2021 Location: Meridian, MS Status: Offline Points: 27	Post Options Post Reply Quote john_sn Report Post Thanks(0) Quote Reply Posted: August-05-2021 at 5:55pm
	Thank you all for your replies! I'll go ahead and order the ARE shaft and coupler, as well as a shaft collar. How can I measure whether the strut is misaligned? If it is, now would be a good time to replace it while the prop is off the shaft.

Jonny Quest Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2995	Post Options Post Reply Quote Jonny Quest Report Post Thanks(0) Quote Reply Posted: August-05-2021 at 6:09pm
	Lots of good info on this site about strut / shaft alignment. As Pete says, alignment starts with the strut. Try the following search string in google: CorrectCraftFan.com shaft alignment Happy reading.
	Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum

Gary S Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096	Post Options Post Reply Quote Gary S Report Post Thanks(0) Quote Reply Posted: August-05-2021 at 6:31pm
	I posted the link to Pete's video in my post above.
	69 Mustang HM SS 95 Nautique Super Sport

gun-driver Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127	Post Options Post Reply Quote gun-driver Report Post Thanks(0) Quote Reply Posted: August-06-2021 at 10:44am
	Since your installing a new shaft, I would put one of these in and eliminate the the old PITA dripping shaft seal. https://skidim.com/flex-gland-system-1.html No more water constantly dripping in the bilge.

wayoutthere Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February-28-2020 Location: Florida Status: Offline Points: 492	Post Options Post Reply Quote wayoutthere Report Post Thanks(0) Quote Reply Posted: August-06-2021 at 3:14pm
	If the dual taper shaft has a retainer nut behind the coupler is the shaft shafety collar still needed ? Asking because i'll be ordering the a.r.e. shaft for my boat after i get back into town. I avoided the dripless because of the plumbing, i didn't know about this version and most likely would have gone that route but got the delrin type from ron instead. Either way no giant wrenches along for the ride. john sn, nice boat that 79, get some pics up and please keep this thread with the new shaft installation and alignment updated with pictures as you complete the work.

Gary S Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096	Post Options Post Reply Quote Gary S Report Post Thanks(0) Quote Reply Posted: August-06-2021 at 4:16pm
	Yes it is. The collar goes between the shaft log and the coupler
	69 Mustang HM SS 95 Nautique Super Sport

john_sn Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: August-02-2021 Location: Meridian, MS Status: Offline Points: 27	Post Options Post Reply Quote john_sn Report Post Thanks(0) Quote Reply Posted: September-02-2021 at 4:51pm
	Hello all! It took me a few weeks but I finally got back on the water. Here's what I did, for anyone else in the future who encounters this problem: Remove the rudder (requires removing rear seat and panel) Take out the old drive shaft Spray some penetrating fluid in the gap between the stuck coupler and transmission flange, then tap the coupler with a rubber mallet until it came loose. Here's a photo of everything taken apart. That coupler was in pretty bad shape. Ordered a new A.R.E driveshaft and coupler (item WS-2000 on skidim) While the drive shaft was out of the boat, I replaced the strut bushings. (This is a good guide for that job: https://www.youtube.com/watch?v=KsqOac-52Rs) I also took off the shaft seal and replaced the packing. That's an easy job when you can pull it out of the boat entirely. Once the new shaft arrived I slid it through the strut and the seal and attached the coupler from inside the boat. This requires a 1 1/16in socket with thin walls, or you can just tighten it hand tight. With the new coupler on the driveshaft I aligned the engine. This video is a good guide: https://www.youtube.com/watch?v=5UqniaiggKA On the 79 SN in particular, to move the engine left and right I used a used a long prybar on one mount while tapping the opposite mount with a rubber mallet. Each tap moved the engine over about a 1/16th of an inch so it took a bit of tapping back and forth to get it aligned side to side. With the engine aligned, I screwed the coupler tight to the flange, then reinstalled the prop. Reinstall the rudder. This was actually the hardest part of the job. Everything else I could do by myself but this required a buddy. Once back on the water, I tightened the shaft seal. It wasn't too big of a job, it just took me a while to learn what needed to be done. Thank you all for your help! -John

8122pbrainard Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045	Post Options Post Reply Quote 8122pbrainard Report Post Thanks(0) Quote Reply Posted: September-02-2021 at 5:15pm
	John, Since it's possible you lost the coupling due to misalignment and fretting, I have some concern about alingnment. Were you able to get the coupling faces down to less than .003" making sure they are parallel? I ask because to mentioned moving the engine side to side but you didn't mention up or down. How was the strut alignment? With the shaft in the strut, did it rotate freely when it was centered in the log?
	54 Atom 77 Tique 64 X55 Dunphy Keep it original, Pete <

john_sn Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: August-02-2021 Location: Meridian, MS Status: Offline Points: 27	Post Options Post Reply Quote john_sn Report Post Thanks(0) Quote Reply Posted: September-02-2021 at 11:37pm
	Pete, Yes, I adjusted the engine up and down as well. I used a .003" feeler gauge to measure the gap at 12, 3, 6, and 9 o'clock. At first the gauge went in freely at 12 and 3 but would not go in at 6 and 9. I moved the engine down and to port, and got to where the gauge went only slightly in with some resistance at each point. However, the shaft was not centered in the log. To center the shaft in the log it would cause resistance down at the strut, so my strut must not be exactly aligned. There is still clearance between the shaft and the log though.

8122pbrainard Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045	Post Options Post Reply Quote 8122pbrainard Report Post Thanks(0) Quote Reply Posted: September-03-2021 at 7:34am
	John, Sounds like you got it. I suggest putting a few hours on the boat and then checking the alignment again.
	54 Atom 77 Tique 64 X55 Dunphy Keep it original, Pete <

wayoutthere Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February-28-2020 Location: Florida Status: Offline Points: 492	Post Options Post Reply Quote wayoutthere Report Post Thanks(0) Quote Reply Posted: September-03-2021 at 10:48pm
	John sn, Great job updating the thread, very well documented, it will help a lot of people for sure. Looks like you did a real good job on the installation as well, doing the homework pays off. After you got back in the water did you have any problems setting the drip drip drip on the shaft seal/ packing gland ?

john_sn Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: August-02-2021 Location: Meridian, MS Status: Offline Points: 27	Post Options Post Reply Quote john_sn Report Post Thanks(0) Quote Reply Posted: September-11-2021 at 7:07pm
	No problems adjusting the seal. I've had to go in and tighten it a couple of times since installing it. Maybe thats just the new seal breaking in.

79 SN drive shaft detached from coupler

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