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Bearing Squeal - Cutlass Bearing

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#1 Fish


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Posted 15 November 2018 - 11:57 AM

Has anyone experienced or familiar with a squeal from a rubber cutlass bearing?


We are commissioning a new drive train (shaft, stern tube bearing and shaft seal). We have an existing (not new) rubber cutlass bearing in the P bracket.

Upon putting it in gear we are getting a prominent noise that appears to be coming from the P bracket, like a whine or grinding noise. This is at idle revs and gets loader fast with minor increase in revs.


We have gotten professional advice that this noise is likely to be bearing squeal from the rubber cutlass bearing. This sounds logical and is consistent with the symptoms.


We have an easy plan and a more involved plan to deal with it, but I'm interested if anyone has experience with this phenomena?


We have no way of knowing if the P bracket is aligned with the shaft, and this may be causing the bearing to bind on the shaft. The bearing was 2 or 3 years old, didn't have any play in it to note, but did have uneven wear, being at the forward bottom and one side, and at the top and the other side at the rear. Due to the nature of the bits we removed and replaced on the shaft and stern gear, the alignment of the P bracket may have always been an issue and we couldn't notice it over a few other issues that are now well and truly resolved. When installing the shaft I did note that it would bind up on the cutlass bearing if it wasn't dead straight, and was tighter than I expected to slide forward once the front was in the stern tube bearing (i.e. allegedly aligned with the P bracket).


Our current plan is to do the on water engine alignment (we have already done the alignment on the hard). If this doesn't resolve the issue (and I'm not actually expecting it to, its just a job that we need to do) then we will dry out and swap the rubber cutlass bearing for a Thordon one. These have greater tolerances and don't squeal when out of alignment. This may reduce the life of the Thordon bearing, but if it goes from a claimed life of 20 yrs to 10 yrs, I don't really care. Plus we've got a tool to change them between tides so its not a major.


The only other option is to take the P bracket off and re-align, which isn't going to happen. Being on a 35 y/o kauri log, there is likely to be movement depending on the weather, and the chances of getting something straight on the hard and it still being straight in the water are not great. - Assuming we've got the right diagnosis of the problem...?

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