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View Full Version : Drive Shaft bolts on Tranny shearing



utah2
09-09-2010, 12:47 AM
Out last week-end, last day of riding, boat was idling back to pick me up, buddy went from neutral to drive and heard a snap/bang and then no go.
I dove under to check prop - ok, checked tranny linkages - ok, then finally saw
a gap between the drive shaft and the tranny. The 4 bolts that connect the shaft to the tranny had all broke.
Anyone else had/seen this before? I repacked the packing nut this spring, everything was working mint.
Also, the prop/shaft are stiff to turn right now with the tranny unbolted, seem right??

MartinCaron
09-09-2010, 12:50 PM
It happens... I tightened them at the begining of the summer because they were all loose

zegm
09-10-2010, 09:45 AM
Out last week-end, last day of riding, boat was idling back to pick me up, buddy went from neutral to drive and heard a snap/bang and then no go.
I dove under to check prop - ok, checked tranny linkages - ok, then finally saw
a gap between the drive shaft and the tranny. The 4 bolts that connect the shaft to the tranny had all broke.
Anyone else had/seen this before? I repacked the packing nut this spring, everything was working mint.
Also, the prop/shaft are stiff to turn right now with the tranny unbolted, seem right??

I actually broke a drive shaft a few years ago on an Old MasterCraft. The engine was sitting on a wooden stringer and the engine mount settled into the wood after years of usage. Well that puts a bow on the driveshaft causing it to snap after years of use. When I replaced the shaft I checked out the bushings in the driveshaft support and they were shot too! However, I would suspect that in your case and not knowing how old your boat is that your packing maybe the issue of the difficulty in turning the driveshaft. You could loosen this first to eliminate this friction point and see if it gets better. If it doesn't then the only source of friction left in the driveshaft support. You will have to pull the driveshaft to inspect this bushing. Not fun to replace either!

phospher
09-10-2010, 10:22 AM
Some of these are reasons why you are suppose to align the tranny every year.

viking
09-10-2010, 09:13 PM
Some of these are reasons why you are suppose to align the tranny every year.

Who on here does that religiously? Never even crossed my mind??

JesseC
09-11-2010, 03:06 PM
I check mine every other year. My suggetsion to anyone that attemps this is to get four sheets of paper and track the changes that you make to each adjustment. What I mean is if you take half a turn out of one and add a turn to the other then you check your alignment you may find that you made the wrong adjustments. What you want to do then is put them all back to what they were before you started. If you track the changes you made to each of the four alignment adjustments, you can always put it back to where it was. If you make three 1/2 turn adjustments to one your paper should show three entrees for half a turn. If you made the wrong adjustment, you know that to get back to where you started you need to do 1 1/2 turns to put it back where it was. I found this VERY helpful. I knew that no matter how bad I got the adjustments off, I could put it back to where it was before I started.

Update: When you jot down the amount of the adjustment I would also add the direction you turned it.

Example: 1/2 clockwise

phospher
09-13-2010, 11:28 AM
Who on here does that religiously? Never even crossed my mind??



I do. It can be a time consuming process but it sure does make a difference. When your boat is out of the water try and turn the prop with your hand. It should turn pretty easy. If it does not, chances are you need an alignment. You would be very surprised how much harder it is to turn a prop that is a few hundreds of an inch out of alignment than one that is within spec of .003. If you have a v-drive it's even more important and a tougher job.

Here's a great post for you direct drive owners.

http://www.correctcraftfan.com/forum/forum_posts.asp?TID=6037&KW=eric+.003+alignment+shaft

viking
09-13-2010, 01:00 PM
Phospher,
Thanks alot for that link. Great info. I'm going to add this to my spring checklist. Damn you learn alot on these forums :)

From what I read on that thread the gap needs to be checked with the bolts OUT? Do you check your alignment this way every year or do you just rotate the prop by hand and if turns easy leave it at that?

Also, a thought that crossed my mind is the engine mounts. I suppose one should check them from time to time too?

DOCDRS
09-13-2010, 02:05 PM
no you do not have to take the bolts out, they just needtobe loose. you have to rotate the shaft 1/4 turn at a time and check the gap. If its out it should be consistant with each turn not moving from that position, if it changes or moves then either your shaft is bent, coupler is out on shaft or coupler is out on the vdrive. if one is out then you have to remove the bolts and spin the shaft couple while the vdrive coupler remains in the same position to determine if its shaft/coupler or vdrive related. btw it only takes about 20 mins to check the alignment on a vdrive , but space is cramped


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