I posted here awhile back about shaft alignment as I tightened down the motor mounds without realizing the consequences....dah!!!! I have read many posts about how to realign the shaft or engine, but someone who has yrears of surveyong experience recently advised me that if I loosen all the mounting bolts and run the engine up through the RPM range, that it will adjust itself and settle in and shaft vibration will pretty much be nulled. Conceptually, this might well work as the engine finds its settling point. Once the alignment has adjusted, slight tightening of the mounting bolts will hold it. Has anyone ever tried this or heard of this? Before I give it a shot, I tohught I would seek any opinions on this recommendation. Thanks Bob 1988 Catalina 30 Universal M-18
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Sounds Crazy to ME!!!
Alignment is controled by adjusting screws to raise or lower the engine and by shifting it side to side. Exactly how do you expect the screws to unlock their lock nuts and tighten(loosen themselves??? Divine intervention??? Though not a mechanic I've worked on cars ,motorcycles and boats and as a general principle things tend to work themselves "out" of adjustment. But it would be great if things just fixed themselves!!!!
Alignment is controled by adjusting screws to raise or lower the engine and by shifting it side to side. Exactly how do you expect the screws to unlock their lock nuts and tighten(loosen themselves??? Divine intervention??? Though not a mechanic I've worked on cars ,motorcycles and boats and as a general principle things tend to work themselves "out" of adjustment. But it would be great if things just fixed themselves!!!!
That is the most ridiculous thing...
I have ever heard. First the motor must be turned off then the transmission coupling made loose. After that you turn the transmission flange by hand and put your feeler guage between the two. If there is any variance I mark it with a sharpie then adjust the engine mounts up, down or sideways until it is perfect then I re-check with the feeler guage on one more turn. If it's out agin repeat the above step. If it all checks out I re-tighten everything and go. Loosening all the mounts and running the engine does nothing but wear away the threads of your motor mounts through vibration. It also does not take tourque into account while the engine is running. Putting it under load would make things worse! This surveyor was a complete and total idiot!
I have ever heard. First the motor must be turned off then the transmission coupling made loose. After that you turn the transmission flange by hand and put your feeler guage between the two. If there is any variance I mark it with a sharpie then adjust the engine mounts up, down or sideways until it is perfect then I re-check with the feeler guage on one more turn. If it's out agin repeat the above step. If it all checks out I re-tighten everything and go. Loosening all the mounts and running the engine does nothing but wear away the threads of your motor mounts through vibration. It also does not take tourque into account while the engine is running. Putting it under load would make things worse! This surveyor was a complete and total idiot!
Never tried it, and probably won't, but it seems
that the torque of the engine would do just as others suggested and throw things out of line. Ever watched an engine closely as you increase engine speed, the prop might stand still and the engine spin if you tightened the packing enough.
that the torque of the engine would do just as others suggested and throw things out of line. Ever watched an engine closely as you increase engine speed, the prop might stand still and the engine spin if you tightened the packing enough.
Bob
There are 4 things to consider when aligning a shaft (just did it yesterday because I was putting in a new engine). 1) engine has to be striaght. 2) engine has to in line with shaft. 3) engine has to be the right height. 4) engine has to have the right tilt. 1 and 2 are adjusted by moving the motor mounts. 3 and 4 are adjusted by moving the nuts up and down on the motor mount shaft. It is best to do 1 and 3 first and then 2 and 4. I found it much easier to know what adjustments to make by not moving the shaft but checking the 4 side of the connection for clearence (north, south, east and west). It really isn't hard, just time consuming. I think it took me 2 hours but I was starting from total scratch. Boy does she run smooth now though
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There are 4 things to consider when aligning a shaft (just did it yesterday because I was putting in a new engine). 1) engine has to be striaght. 2) engine has to in line with shaft. 3) engine has to be the right height. 4) engine has to have the right tilt. 1 and 2 are adjusted by moving the motor mounts. 3 and 4 are adjusted by moving the nuts up and down on the motor mount shaft. It is best to do 1 and 3 first and then 2 and 4. I found it much easier to know what adjustments to make by not moving the shaft but checking the 4 side of the connection for clearence (north, south, east and west). It really isn't hard, just time consuming. I think it took me 2 hours but I was starting from total scratch. Boy does she run smooth now though
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Remember the shaft is best if it is centred in the log tube. You cannot actually see this when doing an alignment so, with the coupling bolts removed, I pull the shaft vertically upwards and measure the distance between flange and hull. Then I press it downwards and measure again and use the average of the two measurements for when the flange bolts are put back in. This sets the position of the prop flange and now the task is to set the engine up to this. Failure to do this can lead to the shaft knocking on the stern tube at certain revs. It makes a fearsome noise but the books often omit this little piece of information.
Remember the shaft is best if it is centred in the log tube. You cannot actually see this when doing an alignment so, with the coupling bolts removed, I pull the shaft vertically upwards and measure the distance between flange and hull. Then I press it downwards and measure again and use the average of the two measurements for when the flange bolts are put back in. This sets the position of the prop flange and now the task is to set the engine up to this. Failure to do this can lead to the shaft knocking on the stern tube at certain revs. It makes a fearsome noise but the books often omit this little piece of information.
Could there be a grain of truth to this madness?
I absolutely agree that there is no short cut to adjusting the elevation and tilt of the engine to align with the shaft. Personally, I've always struggled with the sideways alignment. Pushing on the engine sidways results in temporal changes because of the elasticity of the rubber mounts. I am wondering if once the elevation and tilt is adjusted if I did run the engine with the top lock nuts loose if the lateral alignment would magically fall into place. However, I don't think I would want to run the engine at very high revs. I would want to be tied up to the dock watching the engine. Maybe the madness is contagious and I've been infected.
I absolutely agree that there is no short cut to adjusting the elevation and tilt of the engine to align with the shaft. Personally, I've always struggled with the sideways alignment. Pushing on the engine sidways results in temporal changes because of the elasticity of the rubber mounts. I am wondering if once the elevation and tilt is adjusted if I did run the engine with the top lock nuts loose if the lateral alignment would magically fall into place. However, I don't think I would want to run the engine at very high revs. I would want to be tied up to the dock watching the engine. Maybe the madness is contagious and I've been infected.
This might help a little
When I installed my engine I made a plug with the outside diameter the same as the stern tube and the Inside diameter the shaft size. The I split this plug or bushing(better term) and slipped it into the stern tube( I put a shoulder on the bushing so it wouldn't get lost in there.) This held the shaft in the center of the stern tube and allowed me to move the engine around until I was satisfied with the alignment, bolted it up and removed the wooden bushing. It was no struggle at all.
When I installed my engine I made a plug with the outside diameter the same as the stern tube and the Inside diameter the shaft size. The I split this plug or bushing(better term) and slipped it into the stern tube( I put a shoulder on the bushing so it wouldn't get lost in there.) This held the shaft in the center of the stern tube and allowed me to move the engine around until I was satisfied with the alignment, bolted it up and removed the wooden bushing. It was no struggle at all.
The Rest of the Story........
Okay, so I see a missing bolt that was off the mounting bracket portion that held the engine bracket in place. Strange I thought, so I went out to a hardware store and bought a new one (15/16th). After replacing it I made the unfortunate mistake of tightening them all down, hence the shaft alignment goes south!! How dumb!! At 1100 rpm the vibration kicked in. Now, be advised that the Catalina 30's engine is mounted amidships and is easily accessible on all four sides. Standing over it, all four mounting bolts are observed. No body contortions here!. I try an experiment after reading dozens of responses on shaft alignment. With my wife at the helm, I attach additonal spring and aft lines and I take off the alternator belt to avoid any dangers at that part of the engine. At the dock in forward, my wife revs to 1100 rpm, the vibe kicks in and I proceed with a long extension and socket to go around and adjust the mounting bolts here and their in random sequence just to see if that indeed makes a difference. Well, my efforts payed off as we managed to smooth it out to 1800 rpm. To get it to the higher rpm range requires a trip out on the lake, if I decide to do that. The wake we created was getting abit ugly despite it was early morning on a weekday and no one was on their boats or on the docks. So, their is something to say that adjustments can be made with the engine running providing you feel you are safe (deep socket, extensions and accessibility were key)and perhaps lucky. The surveyer who provided me the, "loosen then run then tighten", advice has been surveying for over 35 years, has one of the best reputations in Georgia and has done this dozens of times and claims it is effective. Who's to argue? I do not think he would recommend this without having the experience to know better. What I worked fine to get me out of the dock and at cruising speed without any problem. I do want though to be able to wind her up to 2300+ rpm to ensure all is balanced. Interesting topic. Bob Catalina 30
Okay, so I see a missing bolt that was off the mounting bracket portion that held the engine bracket in place. Strange I thought, so I went out to a hardware store and bought a new one (15/16th). After replacing it I made the unfortunate mistake of tightening them all down, hence the shaft alignment goes south!! How dumb!! At 1100 rpm the vibration kicked in. Now, be advised that the Catalina 30's engine is mounted amidships and is easily accessible on all four sides. Standing over it, all four mounting bolts are observed. No body contortions here!. I try an experiment after reading dozens of responses on shaft alignment. With my wife at the helm, I attach additonal spring and aft lines and I take off the alternator belt to avoid any dangers at that part of the engine. At the dock in forward, my wife revs to 1100 rpm, the vibe kicks in and I proceed with a long extension and socket to go around and adjust the mounting bolts here and their in random sequence just to see if that indeed makes a difference. Well, my efforts payed off as we managed to smooth it out to 1800 rpm. To get it to the higher rpm range requires a trip out on the lake, if I decide to do that. The wake we created was getting abit ugly despite it was early morning on a weekday and no one was on their boats or on the docks. So, their is something to say that adjustments can be made with the engine running providing you feel you are safe (deep socket, extensions and accessibility were key)and perhaps lucky. The surveyer who provided me the, "loosen then run then tighten", advice has been surveying for over 35 years, has one of the best reputations in Georgia and has done this dozens of times and claims it is effective. Who's to argue? I do not think he would recommend this without having the experience to know better. What I worked fine to get me out of the dock and at cruising speed without any problem. I do want though to be able to wind her up to 2300+ rpm to ensure all is balanced. Interesting topic. Bob Catalina 30
3/1000"
The specs for my shaft alignment is 0.003" and is to be measured with a feeler gauge. As I understand the situation a very small misalignment causes movement or stress that over time will lead to metal fatique and failure. I have no doubt that you can adjust out gross misalignment while the engine is running and the prop is turning. But I wonder if it is precise enough to stand the test of time. By the way in your initial post you said nothing about making adjustments while the engine was running. you said "loosen it up and it would miraculously align itself".
The specs for my shaft alignment is 0.003" and is to be measured with a feeler gauge. As I understand the situation a very small misalignment causes movement or stress that over time will lead to metal fatique and failure. I have no doubt that you can adjust out gross misalignment while the engine is running and the prop is turning. But I wonder if it is precise enough to stand the test of time. By the way in your initial post you said nothing about making adjustments while the engine was running. you said "loosen it up and it would miraculously align itself".
precise alignment
Without doing it precisely with a feeler guage, the strut and bearing will suffer over the long term requiring avoidable maintenance and replacement prematurely, not to mention the wear on the transmission, coupling and shaft seal. As with most things, it's either the easy way or the right way. Don
Without doing it precisely with a feeler guage, the strut and bearing will suffer over the long term requiring avoidable maintenance and replacement prematurely, not to mention the wear on the transmission, coupling and shaft seal. As with most things, it's either the easy way or the right way. Don
Catalina Publishes the proceedure
Catalina owners are fortunate that they have an active OEM who publishes good tech info. The method you describe sounds like the weight of the engine will pivot downward on the Shaft log, which will serve as a fulcrum and then place an upwards load on the cutlass bearing. I suspect there is some miscommunication with the Surveyor who recomended this. You can Rely on Frank Butler and Nigel Calder.
Catalina owners are fortunate that they have an active OEM who publishes good tech info. The method you describe sounds like the weight of the engine will pivot downward on the Shaft log, which will serve as a fulcrum and then place an upwards load on the cutlass bearing. I suspect there is some miscommunication with the Surveyor who recomended this. You can Rely on Frank Butler and Nigel Calder.
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