Don't paint the coupling face
What Chris sees on the bench
- Painted coupling surfaces that have to be cleaned up and shaved down. On one 71 series direct drive the coupling had been in salt water and rusted, so it got replaced instead.
- Grooves and slash marks on a coupling surface where someone had a misalignment problem, got a leak, and tried to cure it with a washer and a bunch of silicone.
What causes it
Between the output coupling of a Velvet Drive, a ZF or any marine transmission and the propeller shaft coupling, you're only allowed 3 to 5 thousandths. It has to be perfect or you will cause damage. Put a gap of paint on there and it's going to be misaligned, and you're going to burn up the transmission or burn up the stuffing box.
Silicone does the same kind of damage. On a direct drive you don't need silicone on the coupling surface. It'll give you a misalignment and wear out the bore. And a washer plus silicone won't cure a leak that was caused by misalignment in the first place. It doesn't work.
Fix and prevention
Don't paint the coupling surface, and don't load it up with silicone or add a washer. If it's already been painted, it needs to be cleaned up and shaved down so it's in good shape, or replaced if it's too far gone.
When to call
If you see paint, sealant or a washer on the coupling faces of your transmission, give us a call before you run it. Call (804) 333-3677, Monday through Friday 9 to 3 Eastern, or email sales@halemarine.com.
Related reading: output nut backing off and coupling damage and Velvet Drive torque specs.