Prop shat alignment makes no sense
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Boat Maintenance
Forum Discription: Discuss maintenance of your Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=7574
Printed Date: May-19-2024 at 3:21am
Topic: Prop shat alignment makes no sense
Posted By: kevman38
Subject: Prop shat alignment makes no sense
Date Posted: July-18-2007 at 10:45pm
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I've read many post as well as read technical details concerning Prop shaft alignment and it still makes no sense.How can you align a ridged coupling (off the transmission )to a non ridged shaft.The shaft floats. If you un bolt and separate it you can move it at least an 1/8 inch or more in all directions.On top of it all It is supposed to be with in .003. If both had ridged mounts/adjustments I could see the magic,But this seems like a guessing game to me.How do I know the center or the alignment of the shaft as it exits the hull.Please tell me what I'm missing here. I can't be alone. I'll go through the motions of checking the gap/spinning the prop ,but I don't think I'll be any closer to knowing if It is really within .003.
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Replies:
Posted By: behindpropeller
Date Posted: July-18-2007 at 11:36pm
The shaft reference is the bearing in the strut, it is not floating like you think.
Once you align the shaft and stop thinking about it, it will make more sense.
Tim
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Posted By: kevman38
Date Posted: July-18-2007 at 11:38pm
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One other thing. Is the tech pub suggesting that the motor be aliened with the natural settling of the shaft ? If that is the case I'm way out of alignment and don't need a feeler gauge to measure that. It's on the order of 1/8 inch up and down and an 1/8 inch side to side.Correct craft in Atlanta did an alignment on this boat about 50 hours ago that has been about 3 years ago (two children in dippers ect). I'm the only operator and know for a fact I haven't hit anything to bend the shaft.
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Posted By: nuttyskier2002
Date Posted: July-19-2007 at 12:49am
The packing gland (stuffing box) with the rubber hose allows for the coupling end of the shaft to move up and down or side to side about 1/4" of more. That is normal. When you mate the two couplings together (unbolted) the .003" feeler gauge should be held tightly as you push the couplers together. This should be checked at top, bottom and either side. Then rotate the shaft coupling 180 deg, mate the two together and check again. Hope this helps! Brian
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95 Malibu Echelon w/Mercruiser 350 Magnum Skier
Former boats:
88 Ski Centurion Tru Trac II
59 Chris Craft Capri (woody)
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Posted By: kevman38
Date Posted: July-19-2007 at 1:17am
In order to mate the couplings I have to move the shaft raise and push the shaft over.I can seat the couplings together no problem. They have a machined shoulder on the inside. Once the shoulders are mated the filler gauge test is good,but what about the shaft manipulation to mate the shoulders ? The final alignment instructions from Ski Dim say:
Push down and lift prop shaft as far as it will move then place shaft in the middle of the movement.The same instructions for port and starboard movement. Where is the center of the movement? you can't measure the center of that movement accurately with out some good dial indicators to .003 . If the shaft is out on the prop side .003 then what does that translate on the transmission side. Also if your strut bearings are worn all measurements are relative to their ware. So should the strut bushings be replaced and the motor aliened to the natural resting place of the shaft?
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Posted By: BuffaloBFN
Date Posted: July-19-2007 at 1:47am
I've wondered the same things while staring down at it...moving it this way and that; physics dictate that it should be dead in line with the bore in the strut. I read in an older thread that, while on trailer, the boot should be removed as an important part to this procedure. The trouble is I didn't completely understand how he meant to do it. Maybe he'll read this and clue us in...I just had my tranny brought back to life and want it perfect!
Greg
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http://correctcraftfan.com/diaries/details.asp?ID=2331&sort=&pagenum=12&yrstart=1986&yrend=1990" rel="nofollow - 1988 BFN-sold
"It's a Livin' Thing...What a Terrible Thing to Lose" ELO
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Posted By: kevman38
Date Posted: July-19-2007 at 2:01am
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Oh I guess this is boat question night.I was going to remove the shaft and install new strut bushings and a dripless shaft seal system as well as alignment.Don't tell me you have to remove the gas tank to drop the rudder to remove the shaft. All of this is well with in my ability, time is the factor. I might just take it in and focus on making money instead of saving it.
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Posted By: 79nautique
Date Posted: July-19-2007 at 2:16am
what year and model boat is it. You don't have to remove the tank to get the rudder off on several models and years the newer boat you do but not the older ones there is plenty of room to get the job done.
Also did you read the posting Eric had on the procedure of aligning the shaft?
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: kevman38
Date Posted: July-19-2007 at 2:32am
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Hey 79 thanks for responding. I know you know correct crafts.The boat is a 1994 sport nautique. The gas tank has a cup molded in the center bottom portion of the tank(for sediment collection I suppose).I don't see any room at all. It's worse than some cobra helicopters I've worked on.I did read Eric's post ,but it did not mention the shaft movement up,down ,left ,right and back to center then align.As I posted I suppose the motor alignment is relative to the natural resting position of the prop shaft.
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Posted By: 79nautique
Date Posted: July-19-2007 at 4:22am
well you need to be able to get to the bolt that clamps the tiller arm to the rudder that is on the side and also the bolt that is vertical on top of the rudder the two should be safty wired together. if you can get those two off then back off the jam not on the packing gland and looseing the packing nut and the rudder should drop down.
for the alignment I wouldn't worry about the movement this way that way or what ever if it doesn't bind while rotating it then your good to go. also it is best if you do this while the boat is in the water at least double check after you done it on the trailer.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: 8122pbrainard
Date Posted: July-19-2007 at 8:45am
Alignment is: engine to strut. The rubber hose from the log to the stuffing box should be removed or loosened so it doesn't apply any side pressure on the shaft. Keep in mind you are not aligning the stuffing box but the engine to the strut. If the strut cutlass is real worn then the shaft will be real loose and it will be a judgement call on where the shaft is parallel to the bore of the strut.
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/diaries/details.asp?ID=1622" rel="nofollow -
54 Atom
/diaries/details.asp?ID=2179" rel="nofollow - 77 Tique
64 X55 Dunphy
Keep it original, Pete
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Posted By: eric lavine
Date Posted: July-19-2007 at 11:36am
we need a refresher course i think, to explain mis alignment simply think of taking a piece of plastic 3 ft pvc pipe and holding it at each end and apply pressure to bend it, you have 2 points and when bent this is mis-alignment in this case you have point A and point B in which with it bent you can feel the strain from bending which creates excessive loads on the driveline, with your 2 hands perfectly in line with eachother the pvc will slide in and out..this i know you will understand. with alignment your simply trying to get the prop shaft perfectly in line with the center of the crankshaft to obtain a load free vibration free driveline. I aligned 2 2 and half shafts yesterday and pulled the couplings loosely together with bolts untill they just touched and then started my alignment pulling the couplings together as the alignment got closer.... oh by the way the plastic pvc represents your prop shaft cause i know someone out there is thinking what does plastic pipe have to do with this?
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"the things you own will start to own you"
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Posted By: Darrel
Date Posted: July-19-2007 at 4:44pm
Kevman, I have a 95 SN, has the same "cup" molded on the bottom of the fuel cell. Its a tight squeeze but its not necc. to move or remove the tank.
Remove the cable from the tiller arm first, then attack the rudder. Have some cardboard or blanket below on the trailer because the rudder will "drop".
Skip the dripless system and get the gortex "rope" from skidim, it is virually dripless and $11.
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Posted By: The Dude
Date Posted: July-20-2007 at 2:25am
kev, darrel is right...you can reach it w/gas tank in. I did it 6 months ago.
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Mullet Free since 93
http://www.correctcraftfan.com/diaries/details.asp?ID=717&sort=&pagenum=1&yrstart=1991&yrend=1995 - 95 Sport
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