Cutlass bearing replacement

M

marykhubby

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Joined
Mar 16, 2007
RO Number
25522
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584
Kenny (Need some input from the Service Meister)
I had both pair of these bearings replaced during winter of 03. How long do they typically last? Will they start showing cracks in the rubber when ready to replace or is this normal Preventive Maintenance? How hard are they to do yourself?
Don

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cracking isn't necessarily an indication of them being bad...but they are on their way. Most people don't replace them until they make a bunch of sqealing noise which indicates the rummber is dry.. I would make sure the powertrains are aligned and see that there is no gap anywhere around the bearing...Replacement usually requires the shafts to be removed.
 
Look for uneven wear, is there any play if you try to shake the shaft back and forth?

Cutlass bearings last many years if your engines are in proper alignment.
 
there should be little side to side or up and down movmnet of the shaft when you push on the prop.
 
Not sure if it's the pic or not, the top pic, looks like he shaft is pressing on the top of the bearing more than the bottom.
 
With the right equipment; bearings can be removed w/o removing shafts. Props, however must be pulled.
 
Some of you may recall I have been chasing a vibration since I purchased her in '03 (small in magnitude - but nagging to a perfectionist like me, cyclic in duration every 2-3 seconds, starts above 2500 rpm increasing some as rpms do, "seems" to be Port side when playing with throttles). Over time I have hired to rebuild both props, dial the shafts, change the cutless bearings, r&r&reglass the port strut mounting base on hull, fabbed/installed steel plates on inside of strbd hull strut mount, re-alignment (JIC), rebuild the rudder uppershaft support, reset the rudder alignment(potential for flutter), and check motor mounts. Has not been an inexpensive ride for my tired ole wallet...

Maybe 150-200 hours since replacing the bearings in 03. Nothing appears uneven to the naked eye. I'll need to get under there and shake the driveshafts again. Last spring I thought I could barely feel/hear slight movement in the forward, port side support, but the others "seemed tight" to me with zero movement/noise.

I've never done this but I am mechanically inclined (was a garage mechanic early in life).
I was thinking... to save money I could drop the shafts (fairly easy?), get shafts/props rebalanced as a unit at a reputable shop, startover replacing all 4 bearings while shafts were out (I assume those 2 forward supports must be cutless bearings too), reinstall, and then pay to have everything realigned by the shop. Those of you who have performed this job - Do you think I am over my head to attempt this and/or need special expensive tools?

My butt tells me this vibration is an early warning sign and wants to find/fix it.
My brain is tired of throwing money at what seems to be a "hit miss" approach.
My gut says the boat is a 1982 design, and I should just learn to live with what may have been there all along.
Sorry for the length, but "What say ye oh wise boaters"?
Don
 
that tool looks great...except the 3607 Aft Cabin has 2 struts per shaft and you cannot use that tool on the "upper" one
 
If yo have two struts per shaft, then the shaft will have to be removed to get the cutlass bearings out. Unless you are only changing the aft bearing.
 
quote:
I have been chasing a vibration since I purchased her in '03 (small in magnitude - but nagging to a perfectionist like me, cyclic in duration every 2-3 seconds, starts above 2500 rpm increasing some as rpms do, "seems" to be Port side when playing with throttles).
Click to expand...

are you certain that the engines are not loosing sync and oscillating around the set rpm?
 
I am surprised to see no evidence of zincs on the shafts.
 
Just because the shaft doesn't seem to be sitting in the middle of the cutlass bearing on land doesn't mean anything. If the hull has flexed even a bit, it will look like you have an alignment problem. Can't tell until the boat has been in the water a few days. Those cutlass bearings look like new.
 
Bruce
I do not understand your feedback concerning oscillation around a "set point". Can you please provide more explanation?

PS: zincs are located between the struts and on rudders (not included in pictures). are you inferring the shaft zincs could contribute to the vibration?
 
out of sync props will cause a beat frequency that is the difference between the two rpms. if the sync doesn’t hold steady the beat freq will vary from zero to some peak then back to zero or a low value.
 
I understand this better now. How would I determine this, and how is it resolved?
I know my sync gage is not wavering, nor are my tachs.
When I adjust the sync gage to either side of dead center (moving throttles) I don't notice any vibration change. I do know one throttle position is higher than the other to achieve gage sync, but that could be a throttle cable adjustment.
 
try using an IR tach to read rpms. You dont need much variation to cuse a beat frequency and that may not show up on your tachs. You will be looking for a cyclic variation that coincides with the vibration you feel
 
If I confirm this cyclic variation using the method you prescribed, what is the fix? Or isn't there one...
Don
 
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