85 Yamaha 90HP lower unit slop. Is this acceptable?

[tawd77]

I just purchased a 90hp yamaha for my boat. It runs great on muffs, but when put in gear, it does have a little engagement clatter (probably due to the SS prop), but at an idle in gear, there is a rattle noise from the prop from time to time, and I noticed that there was a decent amount of slop in the backlash. Is this an abnormal amount for a yamaha? Gear oil looked perfectly clean, with just a small amount of fine metal on drain magnet.

the video is engine off, and shifted into forward. I understand some slop is normal, and will not be noticed once the water resistance is added, but this seemed a little much to me. Your thoughts?

 

[flyingscott]

That is normal when your motor is in gear. That is also not backlash the term is gear lash not that either. Engagement clatter could be you not shifting the motor fast enough be quicker with the shifts. Or your shifting adjustment is out also why you have fine shavings in the lower unit also could be a shifting dog going bad. SS props have nothing to do with the engagement of the shifting.If you can find a pic of the shifting dog and the gears for your motor you will see how they come together and why you have that amount of slop..

 

[tawd77]

Ok, I think i get what your saying. So the slop is between the teeth on the clutch dog, and the spaces where they engage into the forward/reverse gears. This makes sense for reverse, since the teeth on the clutch dog are square blocks, and would have some noticeable slop when engaged into the reverse gear. But the teeth on the forward side of the clutch dog are ramped. So there should be very little free slop when engaged, and I should be able to ratchet(i think thats the purpose for the ramped teeth on the forward side of the dog) the propeller if engaged in forward, and I try to spin the prop backwards by hands, correct?

In forward, there is the same amount of slop as there is in reverse, and there is no ratcheting when trying to push the prop in the opposite direction of rotation.... If that makes any sense.

 

[flyingscott]

If it is suposed to it may be out of adjustment and putting to much pressure on the gears. You may want to call a yamaha dealer to double check. My dad has the same motor I am pretty sure it locks in both directions. But I would double check because it's been a while since I looked at it.

 

[tawd77]

Ok will do, Thanks a bunch for your help!