Why does gearcase have threads and bolts?

[Chris1956]

My '98 Johnny 150HPV6 (60*) has bolts holding the bearing carrier, plus unused threads at the terminal end of the thru hub exhaust housing. Any idea why those threads are there? Maybe for a bearing carrier puller?

I have threads on my Merc gearcase (as is usual), which hold "doughnut" shaped nut that retains the bearing carrier.

 

[Scott Danforth]

to pull the carrier

 

[racerone]

The 2 threaded bolt holes are used to pull the bearing carrier.-----I do not believe you are looking at threads in the housing itself.----Unless they are threads possibly used to screw in a fixture for machining.

 

[Chris1956]

There are threads in the gearcase housing, exactly where Mercury puts theirs, to hold the bearing carrier nut.

I was not able to find a bearing carrier puller that uses those threads. All of them that I found had hooks for the bearing carrier plus the center bolt to push on the propshaft.

 

[racerone]

????----There is no bearing carrier nut on a 98 model 150 HP Johnson outboard.-----The two tabs hold the bearing carrier in place.----The bolt holes for those tabs are used to pull the carrier.

 

[Chris1956]

Right, the Johnson gearcase just has the threads like a Mercury OB gearcase.


My OEM service manual shows the 5/16" threaded rod and puller as the correct tool to pull the bearing carrier.

 

[racerone]

"????----Please look at those " threads " carefully , tell me if it is even a thread !----Maybe just rings for decoration or a labyrinth seal.

 

[Chris1956]

The grooves in my '98 Johnny 150HPV6 60* motor are concentric. That begs the question why? Maybe an expandible jig to install something or test something in the gears.

 

[racerone]

Labyrinth seal.----You agree that it is not a thread then ?-----The driveshaft and pinion are shimmed.-----Rest are all precision parts so no further testing required