Shifting Problems in Lower unit

[AugustMoose87]

So, long story short, I had a shifting problem, and I've traced it to the lower unit. When I pull the lower unit off, and am working with the small gear that rotates to put it in gear, it is MUCH easier to get it into forward than reverse. Is this something that I can take the unit apart and adjust, or am I just screwed??

 

[79Merc80]

Re: Shifting Problems in Lower unit

The year, model, hp rating, and serial # would be a good start to getting your question answered.

 

[AugustMoose87]

Re: Shifting Problems in Lower unit

Good call, sorry, its been a long week...

its a 1978 800 (80 Hp, 4 cylinder) serial 4832396

 

[AugustMoose87]

Re: Shifting Problems in Lower unit

Anybody??? I was at.least hoping to have an idea before I start tearing my lower end apart....

 

[Wingedwheel]

Re: Shifting Problems in Lower unit

Your motor goes into forward much easier because the clutch-dog is spring assisted going into forward and spring opposed going into Rev if that makes sense. You may need to replace the shift cam and cam follower. When you take the cam out, be aware of which side is up. If you put the new one in up-side down you will be tearing the thing apart again.Here are a couple of links with the gear housing breakdown. http://www.boats.net/parts/search/M...OUSING ASSEMBLY, COMPLETE (PAGE 1)/parts.html http://www.boats.net/parts/search/M...OUSING ASSEMBLY, COMPLETE (PAGE 2)/parts.html

 

[AugustMoose87]

Re: Shifting Problems in Lower unit

Thanks. I'm having trouble envisioning how the shifter actually works, so I guess I just have to take it apart and see what I can figure out. I assume there probably isn't an easy/safe way to just lessen the spring tension so that forward becomes a little harder and reverse a little easier??

And any advice on how to tell if I do need to replace the shift cam and follower??


Thanks again

 

[ajgraz]

Re: Shifting Problems in Lower unit

Slowly rotate the prop shaft while manually trying to shift the LU in reverse and see if that eases things up. I'm currently learning more about the differences between how F and R engage myself:
http://forums.iboats.com/showthread.php?t=488758

 

[merc850]

Re: Shifting Problems in Lower unit

The LU should not be shifted into R when the motor is not running due to the design. You can shift while turning the propshaft.If you turn the shiftshaft and it goes into and stays in gear it's OK.

 

[AugustMoose87]

Re: Shifting Problems in Lower unit

Thanks for the pic mecr850, that helped me figure things out A LOT. but it also further confuses me, because it seems to indicate (aleast by my understanding) that the spring is compressed when going into forward and relased while going into reverse.... But Wingedwheel indicated it was the opposite....

The lower unit shifts ok (and yes, I'm turning the shaft while doing so), and the upper half/control box shift ok, but when I put it all together, I can shift in to forward with no problem, but because of the extra resistance in the lower unit while shifting into reverse, one of the cams in the control box slips out of position (with out shifting the motor into reverse), and I then have to take apart the control box to get the cam out of the position its now stuck in.

 

[chum1]

Re: Shifting Problems in Lower unit

so what was the original shifting problem? was the engine running?

 

[Wingedwheel]

Re: Shifting Problems in Lower unit

If the cam in the control box is slipping out of position, I'd think the box may be your problem. There is no way to adjust the spring. How does it shift by hand with the cables loose? You may even have a bad cable.

 

[AugustMoose87]

Re: Shifting Problems in Lower unit

original problem - engine was running, we'd just driven across the lake on a test drive (WAS getting ready to sell it before it had problems...), no issues with forward, guy was wanting to test everything before he bought it, so naturally he tried to throw it into reverse, cam slipped and we had to make our way back with the kicker....

I played and played with it at home and can't get it to not slip (engine running w/ muffs on). the cables just got replaced, so I started working my way from them, box and just cables shift fine, and with the cable unattached, I can shift at the motor with some effort. If I drop the lower unit and hook the cables back up, I can shift everything fine on the top end, and can put a socket on the shifting gear and shift things, again with more resistance going into reverse. if I put EVERYTHING back together, but leave the control box open, I can push the cam into forward and reverse by hand, but if I try to use the shift lever, it slips off the cam....

Edit: I suppose its worth mentioning that this is a new problem - I've used the reverse before, and the only thing that has changed is I took the lower unit off to have a small hole repaired.

 

[ajgraz]

Re: Shifting Problems in Lower unit

There is going to be more resistance going into R than into F, seems that's just the nature of it. And if the cam in the control box is 30+ years old like the motor, maybe the thing's just worn out from all those years of hard labor.

Examine the cam and other control box internal parts really closely to see if there is a worn or cracked spot(s) somewhere in the assembly that's causing the parts to slip apart.

 

[AugustMoose87]

Re: Shifting Problems in Lower unit

STILL trying to get this monkey figured out... Probably didn't help that I didn't work on it at all due to frustration for ~9 months...

I ended up replacing both the cams in the control box... no change. So now I'm almost certain I'm dealing with an issue in the lower unit, maybe back to the shift cam/follower suggestion from before.

Stupid Question #1 - I assume I'll have to take the lower unit apart to inspect/replace those two, yes?

Stupid Question #2 - My buddy let me borrow his Seloc manual, and it makes a pretty big deal about checking backlash before disassembly and after reassembly - Would it be a mistake to assume that they won't change significantly since I don't think I'll be replacing anything that affects the spacing of the pinion or gears (emphasis on think - still having trouble visualizing how its all put together since I still haven't opened it up).

Less Stupid Question #3 - Will it be fairly obvious if the camshaft/follower are the issue?

Less Stupid Question #4 - Is there anything else I should inspect/replace while I'm in there?

Thanks!