Shaft Alignment II

[Howard]

I just did a clitch job on my 1978 Yanmar 8hp and replace some engine mounts at the same time. Now the shaft is very out. I get the picture on adjusting the engine mount bolts up and down to achieve alignment but what do you do with the shaft to make sure that it is in the center of the tube. When my shaft is unbolted from the tranny it sags down and you really can tell where center is when you move it becase of the rubber packing gland tube. Do you have to pull the rubber tube to align it. This means removing the shaft flange (really hard), dropping the rudder (dig a hole behine the boat)and removing the rubber tube ect...Is there any other way to center it.I'd love to see a vedio on how it is done... any out there ? How about books with a step by step and LOTS of photographs ?

 

[Pete]

alignment

Howard, you can do a rough alignment out of the water but you should do all engine shaft alignment IN the water as the hull will change shape thus changing any alignment you did on dry land.You do not remove the rudder or the hose on the packing gland. Alignment is basicaly getting the shaft and engine flanges so that they are matched up.Check the archives for more info. If you are not sure how to do it get a manual or hire a good mechanic. An engine alignment is not that expensive however very critical for reduced wear and vibrations. This would also be a good time to replace (check) the cutlass bearing. It is also critical to geting a good alignment for the cutlass bearing to not be worn out. Hope I did not creat more issuses! Good Luck!

 

[Lee]

Shaft alignement

Howard,You can center the shaft through the stern tube by looking at it from the outside when out of the water. If you don't have someone else to guide you during the coupling alignement, you can maintain the shaft centered by stuffing something between the shaft and the stern tube (from the outside). Then, align the engine mounts so that the two flanges mate with no more that 0.004" space all the way around by using a feeler gauge. Make sure that the shaft is centered through the cutlass bearing as well as the stern tube. I hope this helps. Lee

 

[Kevin L. Woody]

Center may not be correct.

Hello Howard,Your coupling halves have a register of both a male and female of apx. 3/16”. If you loosen the coupling bolts and side the halves apart less then the 3/16” the shaft will not fall off the opposing halve. I would loosen the packing gland and the two hose clamps holding the packing gland in place. Slide it forward to expose the stern tube end and the location of the shaft in the tube. This will only show the shafts location to the tube and nothing to do with its alignment. What is more important is the alignment of the shaft to the strut and to the coupling face. Simply placing the shaft centered to the stern tube could in fact make the alignment off. I would start my alignment first by loosening the packing gland so that you are sure it is not keeping the shaft out of column. Align the couplings, tighten the packing gland down and check the couplings again. If the system was aligned before the mount replacement you simply want to put the engine back to the same location regardless of its centered position to the stern tube. We are really looking for the shaft to sit in the cutlass-bearing square and not so much the shaft to the stern tube. Checking the alignment with the packing nut loose and then tight, will insure that if the shaft is not centered to the stern tube, that the packing gland is not pulling the shaft to one side or out of column. I would think that if the stern tube and the strut have not been moved the engine can be placed back to its starting position duplicating the past installation eliminating the need to move any fixed items. Hope this helps. Kevin