Slipping gear?

[hookups08]

So I just got my prop back from getting rehubbed, put the boat in the water and it seems that I'm slipping out of gear at medium speeds...if I increase throttle slowly I speed up and then it eventually revs up as if in neutral. If j increase throttle fast, I slip out fast. Should I pullnoff the lower unit and take a peek at the gears down there?? Oh, it's a 1960 Johnson 40 hp...

 

[wilde1j]

Re: Slipping gear?

Mechanical shift? If so, there's nothing to 'slip', other than the remote possibility of drive shaft splines letting go or the prop hub is still slipping. Mark it as shown ... if marks move relative to one onother, hub is not good.

 

[hookups08]

Re: Slipping gear?

Yes, mechanical shift. I will mark the hub, if it were the drive shaft splints, what's my method of correction? I am about to put it in the middle of the lake and throw a grenade at it...

 

[F_R]

Re: Slipping gear?

You are sure it isn't cavitating, right?

When it is slipping, does it actually come out of gear (moving the shift lever)? Does it grind and chatter when this is happening? If so, your clutch dog and forward gear are hopelessly worn out long ago.

 

[hookups08]

Re: Slipping gear?

The shift lever does not move, no grinding either. It just sounds as though there is no force moving the prop and my rpms increase...what's cavitation and how would I be able to tell?

 

[F_R]

Re: Slipping gear?

Cavitation is when an air bubble forms around the propeller. Can be caused by motor being too high on the transom, tilt wrong, some kind of obstruction ahead of the propeller, weeds, or something I'm forgetting right now.

Has this motor ever worked properly on this boat?

You don't have to remove the propeller for marking to check for a slipping hub. Just mark the plastic cap and another mark on the prop, aligned with the first one. Run motor till it slips, then stop and look at the marks. If they are no longer aligned, it has slipped. Yeah, ok, I know you said it was just re-hubbed. So maybe it is a defective hub or screwed up in installation.

 

[Vanover]

Re: Slipping gear?

Sounds more like a hub than cavitation. I would think normally cavitation wouldn't come on as quickly from a stop. If i understand you correct you say weather its slow revs or fast it just lets go. If thats the case i would say a hub. As mentioned above just mark it and go for a ride. No grenades needed...yet.

 

[hookups08]

Re: Slipping gear?

I bought this boat/motor earlier this season, in non working condition so I couldn't tell you if it has worked for previous owners... I will remark the prop and give it a test, if by chance I am still aligned, what should be my next course of action.

Thanks for all the insight!!

 

[Tim Frank]

Re: Slipping gear?

It could be as simple as a short shaft motor on a transom that needs a long shaft.
What is transom height?
I am not sure that in 1960 they were building 40 HP in long shaft.

 

[bktheking]

Re: Slipping gear?

Just post a side pic of the motor and make sure the transom bottom is in the pic, that will eliminate any guesswork.

 

[hookups08]

Re: Slipping gear?

Ok I marked the prop and the hub isn't slipping. I did notice a lotnof air bubbles coming from the intake on the lower unit that should draw water to the water pump, when I give it some good throttle more bubbles are coming from above the prop but i can't tell where they originate from