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1985 35hp merc. Broken shift shaft.

muffin

New member
HI
I purchased this motor 8 weeks ago.Fitted it to my boat ,started no bother and was found to be stuck in forward gear.Shift shaft was broken just under top splines.Stripped of bottom end.Removed shaft and had it repaired by top class welder.Rebuilt by the book.Worked well for Aprox.10hrs .BROKE AGAIN,same place.All out again rewelded [thistime built up welding before reducing to exact sizes on lathe] Rebuilt again by the book. Set up in tank with all cables adjusted perfectly.Runs great through F_N_R only up to 25% revs .I dont like to over rev in the tank.Does onyone out there know why this shaft breaks,and is there a cure.
 
Salt water motor ?----------------------Welding will sometimes " crystalize " materials and weaken them.------------Try a new or used shaft.
 
Check the rev lock mechanism for binding on the center section, the 2 hooks must move freely and the shaft must be adjuusted for the right lenth. If thats good make sure the cam on the lower unit which operates the rev lock is located in the right position, the pin should be 1/2 way up the ramp when in neutral. The engine should be locked in the down position when in neutral and reverse. Never shift the controls without the engine running, as the gears won't match and cause cable binding or broken shift shafts. As far as running it in reverse in the tank the engine will only rev so high since the timing is the only thing being changed to speed the engine up......JB
 
HI racerone,
Yes salt water motor. Here in Scotland shafts are not only hard to find but cost from £190 to £220. as i am a pensioner i dont want to spend that mutch just incase it breakes again.
Many thanks,
M.
 
HI beckerjs,
All settings have been done to the SELOC manual. The only coment i have is that the manual states that the top of the ramp should line through the centre of the water pump housing. This would mean that in R and N the lock shaft will sit on top and only when F is engaged will it slide down to release the hooks. Please comment by return.
Many thanks,
M.
 
Try north wales outboard spares mob:07795273148,landline:01248430304 or Bill Hingham 01617907678,are two in the UK that might have what you need,they'll ship to Scotland.
PS I live in Ireland but I usually source most of my spare parts for my merc from the 'States or Canada



 
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I have 2 of these engine, 1 for parts and a factory manual. I can send you the page of how to check but the pic probably won't come through. When in neutral with the lower unit removed the pin should hit the upper part of the ramp but not sit on top. If the pin drops down on the wrong end of the top of the ramp it could lock up your shifter and force you to break something to get it out of reverse. The manual clearly states the engine should lock down in neutral and reverse.
 
Yes you are spot on. Spent today rebuilding as per your instructions and with a little bit of tweeking i now have all things working.Spoke to a Merc lover in Birmingham who asked me to check the rubber mountings under the power unit for wear.Seem ok . He thought that if they were worn it might cause the shift shaft to break.What do you think?
 
Possible I guess, hope not because there are 2 more rubbers under the powerhead. They get wiped out when the lower bearing/seal on the engine fails. Covered in gas and oil they don't last long, soon after engine runs on one cyl and takes out the cranckshaft splines and driveshaft upper splines. Ask me how I know.

JB

becker 1 112.jpg
 
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HI All
Im still here ,at this time i am decorating the livingroom for the she who must be obeyed.Anything to make brownie points.Hope to finish thursday night ,then back to the important work OUTBOARD REPAIRS AND BEER.
M.
 
JB,
I have to ask why? because i have a 90hp mariner with the crank splines striped out is this what could have happen to mine? the drive shaft looks good but it might have been changed before i got it. i bought it ASIS

BT
 
Simple answer is yes. Standard waterpump replacement with a coating of light grease will prevent the 2 from rusting togeather. Lack of maintanance or a problem with the bearing /seal in the crank will wipe out the splines. But so will a bad/bent or dammaged driveshaft, hard to tell without knowing the past.
 
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