96 merc 125 shift cam damage

[bware-]

While coming off plane I accidentally shifted into reverse. After that I couldn't get reverse engagement, just gear clash noise. Forward still worked. Disassemble and inspection revealed damaged shift cam in lower unit. Wear pattern on gears and cogs appeared a liitle off but still serviceable. I replaced damaged cam and reassembled. Worked great for a few forward/reverse shifts on the water, then lost reverse again. Cable adjustment looks good. Disassembled and found same damage to cam. Again replaced damaged cam. Reassembled and went to lake. Guess what, worked fine for a while then again lost reverse. Any idea what I am missing here? What could cause the cam to basically shear?

 

[carholme]

Re: 96 merc 125 shift cam damage

The shift cam is item 18 in this link:

Mercury, Mercruiser, Force, etc. - GEAR HOUSING (DRIVE SHAFT)(3 JAW REVERSE CLUTCH) - 100/115/125 H.P. 80 JET (4 CYLINDER)

It is rotated by the splined lower shift shaft. How do you mean, it is sheared?

What is your engine s/n?

Gerry

 

[bware-]

Re: 96 merc 125 shift cam damage

The "button" on the cam keeps wearing off. Splines are fine. I will post s/n.

 

[Jig 'em Up]

Re: 96 merc 125 shift cam damage

bware- is a buddy of mine who started this thread for me...

Engine S/n is OG387689

Here is a pic of the 2 shift cams that broke. The the one on the right is the first break and the one on the left is the second. This third is still in the lower unit. I have not had time to tear back into it to get it out.

http://forums.iboats.com/attachment.php?attachmentid=202082&d=1373251264&thumb=1&stc=1

Thoughts as to why this is happening?

 

[Faztbullet]

Re: 96 merc 125 shift cam damage

when you pulled prop shaft did the cam follower pin fall out? If so did you put the 3 ball bearings back in? Thays the only thing that comes to mind to make pin hammer the cam like that.

 

[carholme]

Re: 96 merc 125 shift cam damage

Whatever parts failed and caused it to jam against the shift cam to create that kind of damage. it is hard to believe that due to geometry and leverage, that you haven't twisted or nearly sheared the upper shift shaft.

Your s/n comes up as:

MERCURY - (125 H.P. (1996 ))
Serial No: 0G387689 Model No: 1125412SN

Parts List for model 1125412SN:

http://www.crowleymarine.com/mercury-outboard/360.cfm

Service Manual P/N: 90-830234

If you don't have a manual, send me a PM with an email address and I will send you a copy.

Gerry

 

[Jig 'em Up]

Re: 96 merc 125 shift cam damage

when you pulled prop shaft did the cam follower pin fall out? If so did you put the 3 ball bearings back in? Thays the only thing that comes to mind to make pin hammer the cam like that.

I actually replaced the cam follower as well, and all three ball bearing went back in place. Any other ideas?

 

[Tracker&mercury]

I know it’s been awhile but has anyone found the solution for this?