need help on amount of play for driveshaft

[packerman]

Hi,

Can anyone help me with the amount of up and down play I should have in the lower unit drive shaft? It's a "85", 3.0, MR unit w/o preload pin. I have about .050 of movement, maybe all the way to a 1/16". Would I be correct by looking at the way it's laid out that it acts as a shock absorber when putting in gear and pushes up against the erase when under power? Any help appreciated. Thanks.............

 

[uaw9fan]

Re: need help on amount of play for driveshaft

I wouldn't worry about upward play. That is why you have to install the preload tool when you are checking pinion height and forward/rev gear backlash. On older sterndrives the vertical driveshaft bearing was shimmed the opposite way and there was a preload pin in the top of the driveshaft to hold the shaft down into the bearing cup when spinning. Then mercruiser discovered that the shaft has a tendency to push up when spun against the fwd and rev gears so they turned the bearing over and used the bearing cup to limit it's upward travel.

 

[packerman]

Re: need help on amount of play for driveshaft

I don't have a preload tool. Guess I'll leave a bit of room for expansion when it heats up under use and a tad extra bit of play for the pinion gears..... call it good. Thanks for your response.