GEARBOX FAULY OR NOT

[julian0792]

Hello everyone,can anybody help me please.I have a mercury 50 hp two stroke 2003 model.i have just replaced the gearbox housing which was fairly easy.With the gearbox in my hand and whilst turning the driveshaft it sounds very rough.If I pull up on the driveshaft and turn it the it sounds smooth.Should I be able to move the shaft upwards.i even put it back in the old housing and it was the same.Any help would be great,thanks julian

 

[julian0792]

Thanks for the help everyone

 

[Texasmark]

Thanks for the help everyone

Just ease off and give your post time.

As you know, the end of the drive shaft, inside the lower unit has a pinion gear installed that drives the F and R gears. Proper spacing is required to prevent binding. With what you said I would say that you are missing a shim or two to force the drive shaft upwards, like happens when you pull up on it and things get quiet. The manual specifies the clearance but requires a tool to set it. Otherwise it's trial and error on the shim thickness till you get it right.

 

[Chinewalker]

Actually, when pushing down on the shaft, there may be some gear noise. The forces in the gear case tend to push the gears apart (driveshaft upwards), so that may (or may not) be normal, depending on whether gear lash was set correctly when you replaced the housing.