380 AC Cutlass Bearing Info

[Rover4679]

Just a quick note to share a learning regarding cutlass bearings on my 2000, 380, Aft Cabin. After hitting something underwater and having to replace the starboard transmission and shaft, I decided to replace both cutlass bearings since the one shaft was already out. Neither of the bearings "appeared" to have ever been changed and showed a fair bit of wear in the form of no discernable grooves and the rubber had twisted and glazed. I keep my 7.4's tuned and serviced and my top speed at best trim was 19.7 knots and a decent cruising speed was around 16knots. After getting the boat back in the water I immediately noticed that my throttle position was far less for a given speed than before so after a little break-in for the transmission, I throttled up and ran 26.3 knots max. I haven't taken the time yet to figure out the fuel usage difference but I have to believe its significant. Just thought I would share as I would have never believe that the friction from worn cutlass bearings could make that much difference.

 

[dtfeld]

Just a quick note to share a learning regarding cutlass bearings on my 2000, 380, Aft Cabin. After hitting something underwater and having to replace the starboard transmission and shaft, I decided to replace both cutlass bearings since the one shaft was already out. Neither of the bearings "appeared" to have ever been changed and showed a fair bit of wear in the form of no discernable grooves and the rubber had twisted and glazed. I keep my 7.4's tuned and serviced and my top speed at best trim was 19.7 knots and a decent cruising speed was around 16knots. After getting the boat back in the water I immediately noticed that my throttle position was far less for a given speed than before so after a little break-in for the transmission, I throttled up and ran 26.3 knots max. I haven't taken the time yet to figure out the fuel usage difference but I have to believe its significant. Just thought I would share as I would have never believe that the friction from worn cutlass bearings could make that much difference.

I think this is one of those easily overlooked maintenance items. A lot of our boats are getting to the 15-20+ years and likely havent been changed...possibly ever. I've never seen a published lifespan on them either. How often should they be changed?

They are easy enough (but a PITA) to change, but if you ever pull the shafts, its probably a good time to inspect and change.

 

[northern]

Just a quick note to share a learning regarding cutlass bearings on my 2000, 380, Aft Cabin. After hitting something underwater and having to replace the starboard transmission and shaft, I decided to replace both cutlass bearings since the one shaft was already out. Neither of the bearings "appeared" to have ever been changed and showed a fair bit of wear in the form of no discernable grooves and the rubber had twisted and glazed. I keep my 7.4's tuned and serviced and my top speed at best trim was 19.7 knots and a decent cruising speed was around 16knots. After getting the boat back in the water I immediately noticed that my throttle position was far less for a given speed than before so after a little break-in for the transmission, I throttled up and ran 26.3 knots max. I haven't taken the time yet to figure out the fuel usage difference but I have to believe its significant. Just thought I would share as I would have never believe that the friction from worn cutlass bearings could make that much difference.

How many hours on your engines

 

[Rover4679]

How many hours on your engines

840 and 852

 

[Rover4679]

I think this is one of those easily overlooked maintenance items. A lot of our boats are getting to the 15-20+ years and likely havent been changed...possibly ever. I've never seen a published lifespan on them either. How often should they be changed?

They are easy enough (but a PITA) to change, but if you ever pull the shafts, its probably a good time to inspect and change.

One was changed when the shaft was pulled to change the transmission but the was changed using a pull/install tool with the shaft in place and believe it or not, it wasn't that difficult.