Lower unit shift shaft help

[impatico]

I searched and can't find anything about this...

I was given this boat/motor, it's a 1968 Merc 500 thunderbolt. I don't know what was done to it, but it will not shift, I have the lower unit off and was going to put the boat in neutral and the leg in neutral, then reassemble, but I can't get the lower unit to go into neutral. there is no resistance in the shaft, I can easily turn it with two fingers about 90 degrees, if i go past that it feels like it is grinding, and there is no point where it clicks into a gear.

Please tell me I don't need a new lower unit, can't afford one

Thanks for the help

Devin

 

[MatchT]

Re: Lower unit shift shaft help

I a newbie but if your LU is like my 850 thunderbolt, the following is my experience:


if there is a lot of play, you should be in forward test by spinning the prop should only catch spinning one way but free spin the other....turn ccw until you feel resistance, next click should be neutral...test by spinning prop freely both ways, one more click ccw is reverse...test by prop only going about 1/2 turn each way then catching both ways...

try an use a good gripping plier that wont ruin the splines on the lower shift shaft while you do this( tight grip so you dont strip the splines)....

if it does not perform as above, the gears might be bad...way out of my expterties...good luck

 

[impatico]

Re: Lower unit shift shaft help

thanks but as i said no clicking and i can easily spin with my fingers

 

[rickrodd69]

Re: Lower unit shift shaft help

Ive been reading these and other threads and googling and cant really find anything on my 2003 50HP Merc. I lowered the lower unit to replace a water pump. I had it in Forward as my manual said to do. However when i put the lower unit back up and it went up very easily and reconnected the shift shaft all i had was forward. The shifter shifed very hard back into the neutral position but the prop was still in forward. I lowered the unit again and I tried to turn the shift shaft and it doesnt turn freely. I tried with a pliers but am afraid to put too much effort behind it. I'm also not positive which way to turn it. Should i try a vicegrips with a rag? How hard should it be to turn? How far should it turn and will i feel it go into neutral or is it hit and miss? Thank you in advance.

 

[impatico]

Re: Lower unit shift shaft help

you have to turn the prop while turing the shift shaft, use a rag ad vise grips, and I believe you have to go clockwise. Put the boat in neutral, and then find neutral on the lower unit then reassemble.

Hope this helps

 

[rickrodd69]

Re: Lower unit shift shaft help

Thanks, but the prop is in forward now. Which way would i turn it? If i go clockwise it just clicks if i go ccw it moves freely. Im still hesitant about how much effort to put on while trying to turn the shift shaft. The shift shaft has a little play in it but doesnt seem to want to turn and i'm afraid to put too much muscle behind it. Thanks again !

 

[oldnhbuck]

Re: Lower unit shift shaft help

****I want to thank the expert here who answered someone about reinstalling lower units on Mercs..when I find the post after re- reading I'll get your name and thank you personally..****sure bailed me out!!

annyhoo..moving the prop just a hair.. will allow you to "freeup" the shift shaft..so you can turn it w/ your fingers..

you'll notice a LOT (@ 270+ degrees) of free play or slop in the shift shaft (left and right) when LU is in fwd..(this is OK..don't panic!)

to reinstall the LU..place LU in fwd..(prop will 'ratchet' clockwise..and will not turn when you attempt to turn it Counterclockwise..and place shift lever (t-handle) at drivers seat..in fwd..

now..turn the shift shaft all the way counterclockwise..(left..) til it stops..removing all the slop or freeplay from shift shaft..

now it's ready to reinstall LU..

note:

if you look (DOWN..from above)..you'll note that one spline in shift shaft on LU is facing almost straight ahead..

if you look UP..into leg...you'll see that the gearing in the shift shaft 'coupler' on bottom of shiftshaft gear coming down from bottom of powerhead thru the leg/tower has one of the gear 'slots' facing almost straight back..towards where the shift shaft in LU will mate up as you raise LU....


EXPECT a little bit of problem getting the metal exhaust (pipe/sleeve) from the tower/leg (above ....coming from motor assy) into the exhaust gasket behind water pump housing in LU..I usually coat the plastic water sleeve top inside ..and the exhaust pipe/sleeve on the outside ....AND the top and inside of the exhaust gasket w/ new LU oil as a lubricant..before attempting reinstallation of LU..

(remember that the exhaust gasket has to be mounted down inside in LU... behind (and with the front of the gasket partially UNDER the back of the h20 pump housing)..

as you raise LU aligning water sleeve and d/shaft as you lift..the LU shiftshaft gear will almost perfectly align with the shiftshaft coupler in the tower/leg..

if it doesn't want to align and start easily...try putting slight pressure on the prop backwards..(reverse)..

****(Caution..do you have the spark plug wires disconnected? If not..DO IT NOW..you'd be amazed how easily these 2 strokes can start when you don't want them to!!..)***********

if this doesn't "do it"..reach your pointer finger down into the front of the hole in leg housing where you slid the speedo hose up thru..(there is "barely" room..but it will fit..mine does anyway and I have gorilla fingers)...and press down on the shift shaft coupler (feeling the free play in it..) in the leg to help alignment..as you slide the LU up..and align the shift shaft from LU to mate with the coupler (in the leg)..and while holding DOWN on the freeplay in the coupler..I then..grip the base of the shift shaft gear (in LU) w/ needle nose pliers and slightly "lift" the free play (@ 1/4 inch) in the shift shaft of LU..UP...and watch it slide freely into the coupler..then lift/wiggle the LU up a little more and you KNOW the shift shaft gear aligned perfectly with the coupler..and you're not 1 tooth off..
***********************************************
[and just so you don't get mad at me cuz you'll have to drop the LU and realign shiftshaft later if I don't remind you NOW.....AS SOON AS.. ShiftShaft Mates with ShiftShaft coupler...and you move LU just a LITTLE higher..NOW IS THE TIME to install flat washers and lock nuts on the 2 studs on LU in front of h20 pump that now can be seen (threads) starting up thru mating surface of the tower/leg assy..if you don't start them NOW..you'll have to lower LU and start over..cuz you can't get them started later..]
**************************************************

w/ nuts/bolts on LU fingertite..wiggle/jiggle LU and tap the rear of LU w/ heel of your hand..and retighten fingertite as you do this [and as it (LU) goes up]....nuts....... til you hit the plastic on the locknuts..at this point..use a wrench..and slowly watch the gap close as the LU mates..

[this is also a good time to doublecheck that the shiftshaft and coupler didn't come apart..slide your finger back down in hole in upper leg where speedo tube is sticking out and feel for the coupler to be sure it is still splined w/ LU shift shaft]

NOW.......go check the shift control t- handle at driver seat and place into Neutral...walk back to prop and be sure LU is also in Neutral..

then go back to t-handle and place in Reverse..go back to prop and be sure it's in Reverse..if all tests well..tighten LU bolts and then torque them..

I'll admit..the first time was the worse..I mean BAAD....but after 4 or 5 times installing LU..it gets down to where you can easily do it in @ 10 minutes tops..alone..

sorry for the long post..but I wish I had step by step when I did my first one..hope it helps!

Good luck..and long wakes..

 

[oldnhbuck]

Re: Lower unit shift shaft help

re-reading your question..the shift shaft should turn counterclockwise..(left facing the bow of the boat) 1 click from fwd to neutral..and 1 more click from neutral to reverse..and vice versa..

 

[rickrodd69]

Re: Lower unit shift shaft help

Thank you, but i am still confused at a couple statements.

((**to reinstall the LU..place LU in fwd..(prop will 'ratchet' clockwise..and will not turn when you attempt to turn it Counterclockwise..and place shift lever (t-handle) at drivers seat..in fwd..))**

My lower unit is in fwd, prop clicks when turning clockwise, BUT, the prop does turn ccwise but without clicking.

((**if you look (DOWN..from above)..you'll note that one spline in shift shaft on LU is facing almost straight ahead..))**

My shift shaft has no splines, its threaded for a coupling. I have a 2003 50hp.

((**moving the prop just a hair.. will allow you to "freeup" the shift shaft..so you can turn it w/ your fingers..))**

I have moved the prop in both directions more than justa hair and my shift shaft never freed up althought it does have play in it in both directions. I'm just afraid to muscle it too much trying to turn it ccw.


When I lowered the lower unit I had it in Forward as my manual said to do. However when i put the lower unit back up and it went up very easily and reconnected the shift shaft all i had was forward. The shifter shifed very hard back into the neutral position but the prop was still in forward.

Thanks again for any and all help.