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1993 115 4 cyl 2 stroke 2 shift dogs 2 years

G

gene_d

Regular Contributor
2 years ago. just a clanging in reverse. Shift dog cracked. New dog from marineenging.com (listed as merc part) I finished that year and went a few times last year.
First trip this year... same thing happened. I don't shift hard, and I don't force it without engine running. Oil was changed b4 trip. Is there something that could be causing this?
Shift dog.jpg
 
1 (hard to believe) bad metallurgy 2:worn propshaft/cam follower 3: bearing retainer not torqued to specs 4: shift shaft bent?
 
Quicksilver said:
1 (hard to believe) bad metallurgy 2:worn propshaft/cam follower 3: bearing retainer not torqued to specs 4: shift shaft bent?
Click to expand...

The follower (pointed at one end and a groove for ball at other end) and ball were replaced 2 years ago. i will check shift shaft. Is the retainer torque the 2 bolts on the outside in front of prop.? I did follow manual when I did this job. I'm thinking I used torque wrench on them 2 bolts. Thank you for reply.
 
Quicksilver said:
1 (hard to believe) bad metallurgy 2:worn propshaft/cam follower 3: bearing retainer not torqued to specs 4: shift shaft bent?
Click to expand...

i pulled shift shaft. I rolled it on flat counter top. it is bowed, not bent. The high spot when rolled is in the center of shift shaft. About .030. i felt a shaft hole in lower unit. I'm thinking the bottom 2 inches of shift shaft is the important part. That area does not look any more bowed then the rest.
 
Quicksilver said:
1 (hard to believe) bad metallurgy 2:worn propshaft/cam follower 3: bearing retainer not torqued to specs 4: shift shaft bent?
Click to expand...
Took shift shaft to shop today. Looked very close. it was bowed .019 right at the high side of bow I could see where the bore of the housing was rubbing on shaft... It will be replaced. I did not think to look that close... Thanks for help.
 
Someone is shifting this engine into reverse without the engine running, damaging the shift cam. This is a 3 jaw reverse clutch design which only exacerbates non engagement if dry shifted without the prop spinning or the engine running.
 
I got a new cam and new shaft. Merc shifted 12 times and locked in reverse. Broken cam #3. I got another cam from local dealer. This now was shifted 8 times and has now locked in reverse. I am up to 4 cams and 1 shaft. Have not tore apart #4 yet but, 3 cams have been broken on the top side by the numbers. I did not force shift. Most shifts were with engine running on muffs. Does anyone have any other ideas on what could cause this?
 
Cam #4 is not broken out like the rest, but has a pressure dimple in middle of groove at reverse position where the others broke. this time the point of the shift pin is gone. I do not force shift. If IIMG_0707.jpg feel it is not aligned, I spin the prop with my foot.

Is there a spec for how much pressure the spring should have to push dog into reverse? I have the prop on floor with the pin pointing up. I can push shift dog down and into reverse, It takes a pretty good push.
 
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Again the crack is on the high side. Either the cam is too low or the prop shaft is too high ??? Is there anything that can cause mis alignment?
 
racerone said:
Add 0.020" or 0.030" shim ( washer ) under the shift cam if able to do so .
Click to expand...
I am thinking. Grind .030 off top of cam . Could I just install that? Will the point of pin keep cam aligned? Shim sounds great. I don't know how I could keep it in place.
I am wondering if cam is low. Could it be forcing pin to contact prop shaft so hard that the pin in now rotating, and boring out the cam. I think the pin should sit still, hence the 3 ball bearings.
What do you think about grind .030 off top then install? I don't think there is enough room for .030 shim only
 
Just drove 1 hour and got cam #5. I am gonna grind .030 off top. Put red marker in groove. Install prop shaft. Not put on motor. I will shift it with pliers 10 times.
Then pull prop shaft and see red rubbed off? If it looks good, I will put on motor, add oil and fire her up. Shift with running engine.2 times. drain oil, pull prop shaft again. See what I see. I would like to hear any thoughts on this. I know its messed up, I don't know anything else to do.
 
New pin and cam. Ground .030 off top of cam. Used a red dye in cam groove. assembled and shifted with pliers 20 times. Looks like perfect alignment with no breakage. Was not on engine.

IMG_0722.jpgIMG_0723.jpg
 
I put lower unit on. oiled it. Fired up engine on muffs. I removed the cable so I had to shift motor with my hand without any leverage. forward... 5 seconds... neutral... 5 seconds... rev... 5 seconds... neutral... 5 seconds... made it 4 shifts and has locked in reverse.
 
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I pulled prop shaft. There are 3 dimples on reverse area of cam. I am thinking I shifted harder of softer.. But I am thinking the pin is rotating with the prop shaft.
There was no damage without motor running. With running.. 4 shifts and lockup. This has now cost me a fishing trip this weekend. GRRRR. I got new balls and inner rod 2 years ago. What could cause this???

3dimp.jpg
 
I think damage is from spinning pin, not too much force or bad shifting. Grinding .030 made the alignment better. It is now on center. That being said. Its a 28 year old merc. that has been running with a forced sideways pin . Driving again today for new cam.. new pin, new balls, new follower, new spring.(again) The pin does not wobble in shaft much when whole way in, but if I pull it half way out it wobbles.?? If I have the cam aligned with center of prop shaft does the hole clearance even matter? IF marina has a new prop shaft I will see if I can compare.
 
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