Shaft Alignment
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=19428
Printed Date: November-20-2024 at 12:35pm
Topic: Shaft Alignment
Posted By: skfitz
Subject: Shaft Alignment
Date Posted: September-12-2010 at 10:20pm
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The latest in my transmission saga . . .
I installed a new vibration damper on the flywheel, confirmed the transmission pump position and mounted the replacement tranny. I read all the alignment threads here and the excellent write-up on yachtsurvey.com and set out to align the shaft to .003 or better. After hours of trying yesterday, I was unable to achieve alignment. In fact, I would estimate that I didn't get much better than 0.1". What needs to happen in order for it to align is for the front of the engine to move to port. I loosened the front mounts and tried to pry it over (what do you guys pry against?). But the engine would move back to starboard as soon as I let off the pry board. Then I lifted the engine from above using the hooks and pried it towards port when there was no load on the mounts, but the front of the engine still snaps back to port when I take the pry board off. Any ideas? |
Replies:
Posted By: gun-driver
Date Posted: September-12-2010 at 10:34pm
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Loosen the pinch bolts run the nut to the top, give it a couple taps with a hammer to tap it in.
Also do the same in the rear, tap them down you will see the pinch bolt drop. It will move real easy then. I use a pry bar between the motor where the mount goes in and the mount itself. |
Posted By: BuffaloBFN
Date Posted: September-12-2010 at 10:50pm
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Go back to the strut and set the shaft concentric in it. Prop the shaft in position from inside and move the motor to it. I've found that it helps to get it close before the center of the 'halves' are together. That nose in the coupling can mislead.
The other thing if you're getting wierd readings might be that the shaft is bent. Try turning in 90 degree intervals. If the reading changes, the shaft isn't happy. ------------- 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 |
Posted By: jbear
Date Posted: September-12-2010 at 11:07pm
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Right you are Greg..but the dr had me check the strut too. When me and Eddie (well really Eddie) were installing my new shaft after I snapped the old one in TN, we could not get it aligned. Turned out the strut was bent. Got it straight and used gun-driver's method and now it is right on.
john ------------- "Loud pipes save lives" AdamT sez "I'm Canadian and a beaver lover myself"... |
Posted By: 8122pbrainard
Date Posted: September-12-2010 at 11:08pm
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Shawn,
I'd like to back up Greg as he's absolutely correct above. Start with the strut and make sure it's aligned with the hull hole/log first. There's no sense in aligning a engine to a misaligned shaft/strut. Also, backing up Paul, make sure the pinch bolts are loose. Put pressure on the one side with the pry bar and tap the other opposite mount with a hammer to see if it will move in towards the engine. They can be pretty rusted up. Some have had to remove them from the engine and loosen them up on the bench. ------------- /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 < |
Posted By: skfitz
Date Posted: September-12-2010 at 11:23pm
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Pinch bolts are loose. The engine moves up, down, side to side, but it doesn't stay when I try to move it to port.
Loud and clear on the strut alignment. But how could even the worst strut alignment prevent the front of the engine from being moved to port? The shaft isn't even hooked-up??? |
Posted By: gun-driver
Date Posted: September-12-2010 at 11:40pm
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Sounds like the motor isn't sliding on the mount, it sounds like your moving the rubber motor mount itself and then it's returning to the original position.
Is there still room to move the motor to port or are you out of mount play. Will it slide starboard and stay? Do you have the rear loose at the same time as when your trying to move the front? |
Posted By: jbear
Date Posted: September-12-2010 at 11:50pm
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Wow...thanks Pete...agree with those other guys and no mention of me...on the one time I try to get in on a maitenance thread.
john ------------- "Loud pipes save lives" AdamT sez "I'm Canadian and a beaver lover myself"... |
Posted By: skfitz
Date Posted: September-13-2010 at 12:22am
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The first pic has 2 amateurish diagrams I just made. The top diagram shows how much room there is on the port side of each of the front engine mounts. A lot. The black circle is the vertical mount bolt.
The bottom diagram in the first picture is the mount diagram. (see second photo for rear/tranny mount type). What I think is going on is that the tranny mount axis (in red) is not straight and is forcing the engine to the starboard side. Thoughts? 
The second pic shows the mount type. The outside part (on the right, with the vertical surface) bolts to a piece of angle iron lagged into the top of the stringer. I'm thinking I could test my theory by loosening the bolts holding the mounts to the angle iron/stringer. |
Posted By: gun-driver
Date Posted: September-13-2010 at 12:27am
If you don't your fighting against the rear mounts that are trying to hold it square in relation to the rear mounts. |
gun-driver wrote:Posted By: skfitz
Date Posted: September-13-2010 at 12:31am
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Thanks gun. The front will slide starboard and stay.
All of the mounts are loose. But the rear mount being able to slide side to side or up and down would not fix a crooked axis problem. |
Posted By: gun-driver
Date Posted: September-13-2010 at 12:53am
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Is this the same motor that was in there before on the same mounts?
You can cock the motor probably an 1" at the coupler by taking the front all the way left and the rear all the way right. You will have to move the rear a little and then the front a little so on and so on till you get it. |
Posted By: skfitz
Date Posted: September-13-2010 at 1:31am
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Yes, same motor. However, I loosened the front mounts so that I didn't break anything when I lifted the rear to remove the tranny. I didn't tighten the front engine mounts until after installing the replacement transmission with its mounts.
Also, I removed the rear mounts WITH the transmission, leaving only the angle iron on the stringers in the rear. The rear mounts did not want to go easily back where they had been. I'll give your suggestion another try next time I'm out there. |
Posted By: 8122pbrainard
Date Posted: September-13-2010 at 8:31am
It's not. We're just mentioning the strut to log alignment due to it's importance. ------------- /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 < |