#1
IP: 174.65.46.227
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Prop Shaft Alignment
I have a mis-aligned prop shaft and need help correcting it. I can see some scoring on the shaft at the stuffing nut. I can also see that when at low rpm, in gear, that the prop is clearly not spinning straight. I think the engine is too low for the shaft. I have read in a thread that the tail wags the dog and I kinda get it but my question is, How much much authority does the tail have over the dog? Should I un-couple and then raise the engine to meet the shaft coupling where it sits naturally?...or, is it ok to bring the shaft coupling down to meet the drive coupling?
Thanks much |
#2
IP: 71.168.64.202
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usually the engine is shimmed until the two halves of the split coupling
measure equally all the way around as measured with a feeler gauge. |
#3
IP: 173.166.26.241
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First disconnect the coupling and manually hand the shaft around in a broad circle. This will tell you several things. The cutless bearing has likely sustained some wear but may be OK once the alignment is corrected. Roughly in the middle of the wide circle that you are able to turn the coupling is where you want to support it temporarily with pieces of wood. I like to use cedar shingles but most anything will do. The "tail" has now taken it's (as nearly as possible) ideal position. Now the "dog" can be horsed into position using whatever means your engine mounts permit. The factory standard is .003" deviation from true. You will know the engine is in the "sweet" spot when you cannot get the .003" feeler gauge in between the coupling pieces.
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#4
IP: 174.65.46.227
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Perfect word picture.Thanks.
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#5
IP: 206.125.176.3
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Jim,
You probably read that "tail wagging the dog" stuff in my thread from last year where Hanley or Neil told me the same thing. It seems very tedious, but once you get it close, it is simple adjustments with a 1" (25mm worked OK for me too) wrench on the motor mounts. Hanley also reminded me that it works a lot better if you use the AFT motor mounts for large scale adjustments, and then use the FORWARD mounts for the fine tuning when you get it close..at that point the aft mounts become the pivot point and it is easier to dial it in to that 0.003" spec by adjusting the front mounts. I would put the fwd mounts in the middle, then adjust the aft ones to line up the coupler so it mates evenly with the shaft in that 'central' location in the shaft tube..at that point, the shaft half should slide right into the engine half easily and cleanly. Then you can get out the gauge and start your fine tune adjustments. I also had to move my mounts slightly from side to side since I had uneven gaps on the sides of the coupler. A pipe and a sledge hammer eventually moved them the tiny amount I needed.
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) Last edited by sastanley; 02-10-2011 at 09:18 AM. |
#6
IP: 206.230.48.34
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Also, answer the question: why did the engine get misaligned? If it was due to the rubber (or wood) components of the mounts disintegrating you should most certainly replace (or repair) them before you spend time realigning.
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#7
IP: 216.115.121.253
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Just a story
I once worked on a shaft problem on a commercial fishing boat. The vibration was sometimes there, sometimes not. Someone figured out that the warm sun was warping the hull and putting the shaft out. They turned the boat around and the shaft alignment changed. I think is was a pretty crappy boat. No names here.
r.
__________________
Whiskeyjack a '68 Columbia 36 rebuilt A-4 with 2:1 "Since when is napping doing nothing?" |
#8
IP: 174.65.46.227
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I did notice some compression on the ply wood ( I think) that the engine mounts sit on. Have not made a real good inspection yet but wanted to head to the boat armed and ready! Thanks guys.
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#9
IP: 151.200.23.246
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Jim, there are a couple of penetrating epoxy products that will get into the wood and make it sound again...it won't displace (replace?) any moisture though...You'd have to get it dry first, then it will fill the voids & reinforce the rotten parts. Smith's CPES is my favorite..I used it to add some life to my bulkheads to hold off changing them for a couple more years.
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) |
#10
IP: 24.152.131.220
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The tail wags the dog
The alignment to start with is between the cutlass bearing and the inboard end of the shaft log. Doesn't matter if the cutlass is in a remote strut or in a shaft log assembly in the boat's deadwood. With a good bearing, the shaft must be centrally aligned in the shaft log, even space all around. This can only be seen with the stuffing box removed. Once the shaft position is correct (the tail) you can then align the engine to match (the dog).
Ask Shawn what happens when a shaft isn't centered in the log (sorry buddy, but nobody has a more illustrative shaft alignment story than you).
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Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#11
IP: 174.65.46.227
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Shawn, we're waiting! I want pics.
I did a closer inspection. The wood the engine is mounted on (not plywood but a strong laminated wood product. My mistake) is not in bad shape. It's wet and oily but still serviceable. The big issue was that One of the rear mounts was gone... Nowhere to be found. The other rear was so loose I could turn it by hand. Temporarily I moved a front mount to the empty rear so I could attempt to adjust the alignment. I used some thick washers to shim the engine. I did what Hanley suggested, somewhat, but sort of kept my eye on the stuffing box itself. At the point where the shaft seemed center in the stuffing box is where I felt the "tail" was in a good position. I'm sure it's not perfect but for now it might be better aligned than it was. By Hand cranking I think I see an improvement. Not able to fully test yet but will after I replace the hot section, manifold, carb and alternator...and start it up! Some of you guys might remember I had the key in the drive side shaft coulping sheer off because the nut had backed it's way almost off, back some months ago, and had trouble getting the washer to seat properly. I'm happy to report that the nut had backed it's way out only about a groove on the shaft. My solution tonight was to remove the nut and washer and key and cut the key down by 1/8" and was able to get the washer to seat properly. I'm an idiot for not thinking of that months ago. Every suggestion was helpfully. I appreciate it much. I've only had this boat (my first) and engine since May 10th, 2010 and I think I've almost had problems with every system (and repaired it) with the help of this forum. Yuz guyz are great! |
#12
IP: 206.125.176.3
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Well Jim, it all starts & ends in this thread - http://www.moyermarine.com/forums/showthread.php?t=4044
The real fun starts about post #123 But here is a little teaser for you...
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) |
#13
IP: 174.65.46.227
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Wow! Oh yeah, I remember that.
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#14
IP: 128.183.140.38
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How is it that that didn't sink the boat?
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@(^.^)@ Ed 1977 Pearson P-323 "Dolce Vita" with rebuilt Atomic-4 |
#15
IP: 151.200.23.246
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ed, that pic was taken when the boat was safely on the hard again...I had removed the clamps and slid the stuffing box hose forward to expose the culprit. That is the hole that was worn from the shaft in between the hose clamps, so the hose & clamps were the only thing keeping the boat afloat. Additionally, I had chipped away all of the marine tex which was really what probably kept the boat from sinking.
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) Last edited by sastanley; 02-10-2011 at 10:02 PM. |
#16
IP: 128.183.140.38
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Shawn,
After I saw that, I went back and read the whole 300+ post thread. What a saga! You had it worse than me last season! I only lost the last half of the summer. Sounds like you lost almost the whole season. I was particularly interested in all the comments on engine alignment, as I have to tackle that on my rebuilt engine as soon as it warms up some. I was talking to a friend about it last night, and he has an interesting way of centering the shaft in the tube before aligning. This only works if you have a strut and are out of the water. Without removing either flange or prop, he backs the shaft out a few inches, spools vinyl tape onto it just where it leaves the tube until its the dia of the inside of the tube, and then pushes the shaft back into position. This firmly holds the shaft centered in the tube while he aligns the engine. Then he backs the shaft back out, unwinds the tape, and pushes the shaft back. Neat!
__________________
@(^.^)@ Ed 1977 Pearson P-323 "Dolce Vita" with rebuilt Atomic-4 |
#17
IP: 174.65.46.227
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I have the rail mounted system and can see the depression left in the wood from years of that engine sitting there. I'm going to have to shim but want to know what others have used to shim, that is effective and long lasting.
I know what Hanley is going to say. (Cut rails down 2 1/2" and install the Moyer mounts.) That's a great option but I can never get a straight cut with a saw. Shimming is easier also. |
#18
IP: 173.166.26.241
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Another option is using so called "front end" shims available at NAPA in various thicknesses. I do not like the Globe plastic wedge concept. The NAPA shims are not stainless but can be oiled, greased or buried in paint.
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#19
IP: 174.65.46.227
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Thank you Hanley
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#20
IP: 173.166.26.241
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Here's one I had in the shop.
Last edited by hanleyclifford; 07-13-2016 at 08:36 PM. |
#21
IP: 174.65.46.227
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Here is video of my continuing saga on the prop shaft alignment. I'm not sure if the shaft is bent or the engine is just misaligned. I tried shimming it upwards and it seemed to get worse. Opinions?
http://www.youtube.com/watch?v=D4IsGni6NHE |
#22
IP: 97.92.210.145
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Ironical
Just this week I finished a class IN Motor Alignment./
I am an electrician in the Steel Industry, and as a continual education, we are sent to classes in different areas of expertise. The first thing you need to do is find the Angular difference between the motor and the shaft. this is done by several different methods,, depending on your means. Feeler gauge is what I intend on using,, because of the close proximity of the output flange to the drive coupler. I have much more input on this if you would like to continue this topic.. it could be its own thread though, so I will wait and see where this goes.. Basic though,, first you want up and down alignment, saving yourself some upward movement for overall adjustment. to the output medium, save that you don't need to undercut your base of the driver,, the motor, to the drive shaft. EDIT, You can bring it UP Overall with shims ,but down is much more difficult. THEN,, you will need to check your side to side adjustment. Industry Standard is .004 for minimal vibration. Once you get your Parallel adjustment for height ,, and then your side to side adjustment for angular displacement ,, you are in the Ball park. Ball park is what you shoot for first,,, then you get more critical,, Starts with eye balling,, then gets down to the gnats ass,,with a dial indicator if you want. There are adjustments that have such acronyms a RCH's.. which also have adult ratings. Ask and I will look in the books they gave me, and elaborate more...
__________________
With Powerboats, it's about the destination. With Sailboats, you are already there. Jeff S/V Karinya 1973 Grampian 30', Full Keel, A4 aux. Last edited by 13jeff13; 03-05-2011 at 11:01 PM. Reason: .004 not .0004 |
#23
IP: 97.92.210.145
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Yikes
Reading back on some of the posts,, There Rises many other aspects to this. SOFT FOOT is a common problem in motor alignment. as in you think you are in the ball park and then when you tighten down you are OUT of alignment,, you have a soft side , or mounting plate, or bent foot..
__________________
With Powerboats, it's about the destination. With Sailboats, you are already there. Jeff S/V Karinya 1973 Grampian 30', Full Keel, A4 aux. Last edited by 13jeff13; 03-05-2011 at 02:52 AM. |
#24
IP: 70.188.238.132
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Hull Flex
Many factors can cause alignment issues. I think I have seen most. A few years back a neighbor brought his Borg Warner CR2 gear to me for repair as the rear seal had gone, oil leaked out and "all melt down". I rebuilt it at great expense as the BW CR2 was discontinued several years ago and parts are $$$. He mentioned that Ding Dong Marine had repaired it the year before at great expense.
We reinstalled it and within a few months "all melt down" Well, I found a BW Velvet Drive, not a CR2 and we modified his stringers and mounts to accommodate the different height. After installation I went along with my dial indicator to check out the install. At idle speed attached to the dock, it was spot on. Then we went for a ride. At about 1500 RPms on the Ford Lehman, the dial indicator indicated .050 out!!! Further examination revealed the hull of the 34' TTT, (Taiwan Turkey Trawler), was flexing as power was applied. I refused to warranty the gearbox and asked for a thorough examination of the stringers. Turns out they were rotten for about 20 feet, so as power was applied the entire hull flexed, thus allowing major misalignment and subsequent damage to the output shaft seal, bearings, etc. Now the saga continues... This "Frugal Fellow" hired a local shade tree boat fixer to open up the stringers, one side only and pound in short pieces of 2" X 4". At this point I washed my hands of this job and walked away. Just proves that some powerboaters can be a cheap as us sailboaters. Tom |
#25
IP: 173.166.26.241
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Around here we call that "pennywise and pound foolish". BTW, Jeff, the marine industry standard for drive line tolerance is .003". We're a sloppy lot.
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