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40hp mercury 1983 gearbox trouble

brentle

Regular Contributor
"Greetings once again JB, I ha

"Greetings once again JB, I have since fixed all the other problems with water into the bottom cylinder but now i am having trouble when putting the bottom leg back on!! I have the DIY CD manual that tells me that the selector should be in Forwards gear on the shift shaft and the merc controls also in FWD, but when i put it together and return the controls back to neutral i have to pull it back into reverse a little bit to get it to disengage FWD as if it is sticking. I noticed when selecting the FWD gear by hand with the leg off it is very stiff and clicks into gear with a clunk. then when I try and turn the prop it spins the drive shaft in both directions and is locked IE: no free spin in opposing direction as it does in reverse. I have not dismantled the lower leg at all and it was working fine before. I have checked all adjustment settings for linkage and they seem in order. Also if the gearbox is in FWD and I try and slide the selector back to neutral by hand when the cable is disconnected it jerks back almost into reverse like it is spring loaded. i have tried all different adjustments But it the shift shaft seemed preloaded with pressure and isnt sliding into FWD gear easily as reverse does. Please help I have tried everything i can think of. the problem is definately in the lower leg shift shaft unit but i cannot see how to resolve it."
 
"remove lower unit, put it in

"remove lower unit, put it in neutral with pliers if you have to. Put controls in nuetral. The cam on the shift shaft hits a pin when reverse is selected to lock it down, it should be positioned so the pin is at the bottom of the ramp in neutral. With everything in nuetral, the prop should spin freely, re-install lower unit, yes in neutral. As you install it, spin prop to verify its in neutral, wiggle flywheel and align shift shaft splines, when done it should still be in neutral. Make sure water tube goes in pump. Engine should lock down in reverse. Let me know if you need more info. There is also rigging for position of shift cable."
 
"If i select the shift shaft i

"If i select the shift shaft into neutral it clicks in and the prop spins freely. But when i click it a futher bit CW it goes into REV in stead of FWD then there is about 180 deg of free play before it bites into another gear then its all backwards. i know the shift shaft should be able to select FWD/NEUT/REV gears within a 30-40deg turn on the shaft but it will only do it smoothly when its all working back to front. I have tried what you said by locking the shift shaft into neutral but when it is all back together when i select FWD with the controls the prop is now locking in reverse and clicks when turned forwards and vice versa when the controls are in reverse. the shift feels good and smooth but everything is backwards. although it doesn't feel as smooth when around the way i initially had it but (as from my previous post), i cannot get the same smooth gear locking setings on the shift shaft any other way. i have been playing around with this for days and have had the bottom leg off more times now than i think ive ever had hot dinners. i have looked over the manual but it doesnt specify what to do if the shift shaft has been upset out of position when the lower leg is removed. the diagrams arent helpful either!!! Also in any setting i have tried so far i cannot get the leg to lock when in reverse. I have tried numerous settings on the locking cam (BY THE BOOK) but it seems to also be upsetting gear selection and jams up the shift mechanism. REV is selected in CCW and FWD in CW on shift shatf right??"
 
"the shift shaft on the leg is

"the shift shaft on the leg is the problem, it has gone out of position and needs to be turned counterclockwise 180 degress. do not re-install it till you have it right. when correct and in
fwd gear the prop will ratchet when turned clockwise, not ratchet when turned counterclockwise. When in neutral the prop will spin freely. when in reverse the prop will ratchet when turned counterclockwise and not ratchet when turned clockwise.
Again, the shift shaft is 180 degrees or so out and needs to be set correctly, then when in neutral the cam with the ramp facing forward will engage the lock. If you changed the lock setting be carfull not to jam the linkage by having it too tight. Do not install in fwd gear again."
 
so what you are saying is that

so what you are saying is that the prop spins clockwise when running in reverse gear? and the prop spins counterclockwise when in forwards gear? i looked at that cause that how i originally had it but it looked like the prop would be working against the flow?? Now I am confused. the pitch on the prop looks as if it should spin Clockwise when running in forwards gear!!
 
Props on the mercury motors wi

Props on the mercury motors will ratchet in one direction!!! When it is in forward it will ratchet going clockwise ( Remember you are turning the prop not the drive shaft ) that is just the way it works.Pay close attention to the advice given ( by JB )and you will have no problem.AND THE PROP SPINS CLOCKWISE WHEN IN FORWARD AND THE MOTOR IS RUNNING.
 
"Thanks, i wont take anymore a

"Thanks, i wont take anymore advice from my mates who said it shouldnt rachet clockwise in forwards!! it would have saved me 4 days of mucking around. Anyway i did what JB said and took it out for a spin and hey presto it worked. WOT got it up on the plane and cruised along nicely. Just a few more tweaks to throttle and timing adjustments and I am set for the remainder of the season. thanks again guys."
 
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