reattaching drive shaft

[stanleyi]

vibration in reverse
A couple of weeks ago I reported a vibration on my 33 ft. Hunter Cherubini (1980) when put into reverse. Three of the four bolts holding the coupling plates together between the back of the transmission and the front end of the propeller shaft were missing and there was some apparent misalignment of the shaft on closer inspection. My plan is to replace the missing bolts on my return to the boat next week-end. Here is my question: Should I be concerned about torquing down the bolts or should it work to simply replace the bolts and snug them down by hand? Also, should I use a feeler gage on opposite sides of the coupling plate or take any other precautions to be sure of the alignment. Not having done this before, I need all the advise I can get.
thanks,
Stan

 

[Stu Jackson]

Stan, I've thrown a few coupling bolts on our boat over the years. Here are a few ideas:

Buy ONLY fine threaded bolts and nuts. Coarse threads won't give you enough teeth to work with. In my case, as maybe in yours, there isn't room for long (i.e., easy to work with) bolts, so the longest ones that will fit without hitting the areas forward of the couplings will seem awfully short to work with. Mine were such that I couldn't even find space for lock washers or even the star lock washers. I also couldn't get the bolts to go in from forward to aft, so I had to feel around to get the nuts on on the forward side - working blind. I used a bit of blue Locktite. They've been holding that way now for years, but I check them regularly and have them on my periodic monthly checklist. Tighten them, but you most likely won't have room for brute force - remember, sooner or later you'll want/need to remove them - don't make it permanent.

Good luck.

 

[kloudie1]

Usuallly the bolts will not loosen unless the alignment is off a good bit. Do the alignment as best you can and like Stu says fine threaded bolts .. lockwashers if you can.. tighten the best you can using normal hand wrenches .. best if you can get a torque wrench but if you can't, try to get even tension on all four.

 

[Claude L.-Auger]

Ditto Stu and Kloudie. On my boat, after measuring the space from the tranny housing to the inside face of the flange I find it easier to install the short bolts from the outside of the shaft flange with the nuts inside. That allows me the use of lockwashers. And, using a short open-end wrench with the other end on the floor I have the space to put proper tension. Do it in sequence, going to the opposide side bolt, i.e 1-3-4-2. Increase your tightening in 2 or 3 passes so as to tighten evenly all around.

 

[stanleyi]

Thanks to Stu, Klondie, and Claude for response to my driveshaft problem. Nice to know that the bolts can fall out and to check them periodically. I am curious to know where the missing bolts went. Perhaps when the original engine was changed out and the new Vetus was inserted, someone left out a couple of the bolts. I will see if they can be retrieved with a magnet from under the engine where I can't see or get to.
Thanks again.

 

[Benny17441]

I would also replace that remaining bolt at this time.

 

[Stu Jackson]

That's always been part of the "fun" about this on my boat. Really. I can tell (from experience) when one of them flies off because of the particularly peculiar sound underfoot when motoring. Took me a few times to learn it, but now I know and am glad I haven't heard it in a long time. But what happens to me is that the bolt and nut are sitting right there underneath the coupling every time, even though there is a route for them to roll forward under the engine. I think they fly off, hit something above or to the side, and then just drop under the coupling!!! They sure don't fall off when the engine isn't in gear! One time, many, many years ago, I heard the noise, went down to look and saw THREE of them just sitting there. After giving myself a Dope Slap for being the idiot who put them back on the last time (!), my friend Dave and I put in immediately to a side tie dock, reinstalled them and were on our way. Since we were going out for a race, we learned how to do it in record time! All part of the general fun and games. Enjoy.