Can a lower unit slip??

[rhaser]

I have a 76 85 hp runs like a top. once i throttle up it takes off great then when i just up on plane the motor revs like the prop is cavitateing i can throttle down and seems to work good under load. ive changed the prop and made sure the motor is all the way down. it doesn't pop out of gear. in fact sometimes i have go past nuetral toward reverse to get it in nuetral. any thoughts

 

[wilde1j]

Re: Can a lower unit slip??

LU can't slip. You may need to adjust shift cable. See OEM shop manual for procedure.

 

[Chinewalker]

Re: Can a lower unit slip??

It can't slip... smoothly. When they do "slip" they do so violently when the clutch dog pops out of the gear.

Has this rig ever performed properly for you? Have you made any changes to the set up lately? Motor height? Prop style? Pitch? You said you tried a different prop. Was it a new prop? Your symptoms sound like a spun hub. Before changing the prop, mark the prop hub and prop nut with a Sharpie and note whether your marks are still aligned after running.

 

[rhaser]

Re: Can a lower unit slip??

I didn't think so. but why does it work fine under heavy load till it planes? i throttle back down and it seems to grab? these are both new cables. It doesn't seem to be poping out of gear? Its been running fine all season til now. I should be able to disconect the cable and manually hold it gear right? And see if i still have the prob?

 

[rhaser]

Re: Can a lower unit slip??

used props but ive spun the hub on this boat before twice.both times couldn't get it to go faster than idle. i lowerd the motor last yr because the previous owner put a short shaft motor on in the long shaft holes. jumps out the hole great an used to plane out faster. i ve running it like this for a yr. it happened as soon as i left the nowake zone. i carry a spare prop so i went back to the dock and changed it same exact prob? the motor is lowering all the way also?

 

[archcycle]

Re: Can a lower unit slip??

wilde1j gave you a great place to start. the fact that your shifter sometimes requires you to go Past N to get to N means it's clearly not set right at the linkage on the motor. even if there is another problem causing this then your linkage is still going to be the first thing that needs to be set properly before moving on.

 

[wmconway]

Re: Can a lower unit slip??

If your shifter is not properly adjusted, you could be hearing a loud buzzing whenever you shift it into gear. This is the clutch dogs being ground down. Check your lower unit lube for metal shavings. I don't believe that you would have two props with hubs spun to the same degree. You may also want to check the driveshaft and propshaft splines for shearing.

 

[rhaser]

Re: Can a lower unit slip??

Wmconway that sounds better. the lower unit does not look orignal. i have 1 more prop to try and i will mark it to see if it's spun. No clunking or grinding. i did ckeck the lower unit oil no water or metal? i'm thinking some thing sheared also. just never ever seen it. what would be a way to check that?

 

[rhaser]

Re: Can a lower unit slip??

Achcycle yes they are 1 inch longer than they were. if its in gear and doesn't pop out that seems it's working? It only revs/slips when i get up to plane? then no load and somthing shifts around? if i throttle down to just before plane its fine? no clunking or grinding?

 

[wmconway]

Re: Can a lower unit slip??

Archcycle and Wild1j are right!! You have to get the shifter adjusted right first. If it is barely engaging in forward gear, it could be slipping out at high speed and you might not hear it over the engine noise. Furthermore, when you shift into reverse, you are binding on the shift rod and may end up damaging the mechanism. At a minimum, i'd remove the LU and have a look at the driveshaft and check the shifting action. Do you have a lot of play on the propshaft?

 

[rhaser]

Re: Can a lower unit slip??

TY WM no play in the prop shaft ill mess with the adjustment this weekend!!