lower unit drive shaft freeplay 88SPL

[MAW31]

evinrude 88SPL lower unit inspection:

dropped the lower unit on my outboard to replace the impeller...

while the unit is on its side, I noticed that drive shaft actually has some free play on it back and forth.

if I push the drive shaft into the lower unit and turn at the same time by hand, I can feel it clunking as I turn.

However, if i pull outwards on the driveshaft and turn, its smooth as glass.

Is this freeplay normal or signs of excessive wear?

 

[Texasmark]

Re: lower unit drive shaft freeplay 88SPL

There has to be some play to allow for manufacturing tolerances so that all engines built to one set of drawings can be assembled. I would assume that under power, the thrust of the gears on one-another would cause the gears to push away from each other as far as these tolerances allow. Over time they will wear-in with each other and produce a match which should be very slick and smooth.

Manually turning the shaft with downward pressure on it probably moves the gears into an area where they don't normally run and there will be some roughage there. You wouldn't feel this on a new engine that hasn't had time to develop it's groove.

Know nothing about the life of your engine, but considering it has been maintained with fresh oil and no water over it's life, I wouldn't worry about it.

Mark.

 

[MAW31]

Re: lower unit drive shaft freeplay 88SPL

Its a 1995.

I had thought (like you said) that since the the motor always turns clockwise and the way the pinion teeth are angled that that rotation would naturally place an outward force on the driveshaft (and thus into the thrust bearing) ...but then, I"m constantly overthinking this stuff...

Thanks

 

[Faztbullet]

Re: lower unit drive shaft freeplay 88SPL

Omc/Brp housings are precision machined to tolerances that why you only shim the pinion height, whereas a Merc you do foward/reverse gear and pinion depth/height/backlash. What you have is the 2 piece driveshaft and the upper shaft itself just clips into lowershaft. It will be very sloppy, enough that sometimes you can make the upper seals leak in pressure/vac testing by moving shaft side to side and if you lay in on its side it may even weep gear oil from seals. This is normal in this style(2 piece) units..