Direct drive transmission squeal

[Sammamish Skier]

While out skiing today we noticed a strange squeal from what appears to be our transmission when the shaft is barely turning and the boat is in neutral and coming to rest. I think these transmissions have a brake so maybe it's worn? Fluids look normal, but I'm going to pull the filter to check for debris. The transmission sounds fine otherwise. Anyone ever run into this?

[Capt Rick]

The direct drive when in nuetral should not turn the shaft. ( indicates bad clutch plates)

The gears should be quite above 1200rpm. in gear, rattle is common under 1200. ]


Bad shaft packing, bad alignment, worn cutlass bearing are all items that can squel.

Capt Rick

[Sammamish Skier]

I dont think it's the clutch as the noise comes from the output shaft coming to rest when the prop is driven by the momentum of the boat.  I'll have to check the packing and alignment.

[Water Sports]

We had same noise at low idle.  Found out to be thrust plate between flywheel and trans.  Caused by corrosion of bushings on plate.  Only way to find out is to remove trans.  Didn't cause any damage just annoying. Doug

[Sammamish Skier]

Took the boat to a shop it appears that this was an air leak in the filter seal. Still testing to be sure. On a positive note the hsw450 which is in the direct drive boats is still being made as the  zf45a and according to ZF it can get conditional approval from the factory for use in our boats given that WOT is 500 rpm above factory specs for the zf45a.

[Sammamish Skier]

One more update on this. The squeal returned shortly after I made this post. Had the alignment checked and it was fairly far out. Fixing the alignment got rid of the squeal. It also made the boat quieter at speed.