FLAT NECKLACE 85mm.

Function and technical context

The 85mm flat collar is a fastening and sealing element used in drive assemblies, tail shafts and coupling systems on outboard and tailed outboard marine engines. Its function is to maintain the correct axial positioning of the rotating components, avoiding longitudinal displacements that would compromise the alignment of the assembly. It usually works in the transmission area or in the propulsion system, where mechanical tolerances are strict and any play can generate vibrations, premature wear of seals or loss of efficiency in torque transmission. A bad collar can cause excessive axial play, which accelerates the deterioration of adjacent components such as bearings, O-rings, and shaft seals.

When to replace this part?

The most common symptoms of a worn or damaged flat collar include abnormal vibrations in the drive shaft, metallic noise in the tail during cruising, and noticeable play when manually moving the shaft. It is recommended to inspect the collar at each seasonal maintenance or whenever the transmission unit is disassembled to check seals and bearings. Replacing it preventively during a scheduled inspection is significantly more economical than facing a breakdown at sea due to misalignment of the propulsion assembly.

Compatibility table