MC-1 Drive Dog failure?

[ratdude747]

Spent a bit fiddling with it. I already had it at 6"...

I eventually found a setting (backed off helm cable 6 turns instead of 4) that allowed for full engagement both directions and not using up all of my slot adjust (still using about 70% of it). Here's a video of my current results:

I can't get it to not ratchet at all after reverse and reverse not ratchet hard in gear (hand spinning). Going to have to be good enough, at least for now... it's way better than it was!

 

[ratdude747]

Did some checking on the other two lower cases I have.

Pulled the TN drive's impeller for laughs.. yeah, it was completly roached. Didn't take out the housing... but no wonder the guide tube was melted! Due to the case damage and stiff shifter, it's not favored for reuse.

The Gary drive needs a new prop seal... it had ran over some netting which took out said seal. From what I'm seeing this can be replaced without tearing the gear case down. The shifting feels good and unlike my current one, seems to be in the right "finger" positions (on the current drive, forward doesn't make it to straight- I think it's a bit past?). The skeg is missing a few chunks but not completely gone... might be weldable. Has a thick and ugly (brushed, not sprayed) repaint job that I don't care for but isn't a deal breaker. The big question is what condition the gears and bearings are in, considering how bad the upper case was. At some point soon I'll pull the lower case and impeller and feel. If the gears feel good, maybe just needs a new impeller and prop seal and would be a good backup case given the suspected wear issues with my current lower.

 

[ratdude747]

Two outings later, I have some findings:

• The drive doesn't shift right when trimmed up any significant amount. Seems my shift fork is loose and gravity is having an effect?
• My shifting went to crap like it had been during yesterday's outing... came to check it tonight and it's not locking in either direction. I'll attempt to readjust it this week... is it normal for this to happen, or is something breaking on me?

Maybe I need to swap lower units sooner rather than later?

 

[ratdude747]

Something is pooched. Couldn't obtain a usable adjustment (closest I came was popping hard out of gear when pushed). Per some fresh measurements:

• Helm cable has 2 15/16" travel (in spec, a lot of slop, this was measured with it pushing/pulling the lower cable to obtain the minimum travel)
• Lower cable has nearly 7/8" of play... that be the problem. Cable is slow/stiff, but it's been that way since assembly.

Given that the lower cable and upper case shift parts are all virtually new, am I safe to conclude my lower case (and it's shifting hardware) is the problem?

Might want go get a new prop seal and impeller kit for the spare lower... hard to say if it's smooth turning (some roughness, but I don't know if that's due to a lack of preload).

Thoughts on how to proceed?

 

[ratdude747]

Something is pooched. Couldn't obtain a usable adjustment (closest I came was popping hard out of gear when pushed). Per some fresh measurements:

• Helm cable has 2 15/16" travel (in spec, a lot of slop, this was measured with it pushing/pulling the lower cable to obtain the minimum travel)
• Lower cable has nearly 7/8" of play... that be the problem. Cable is slow/stiff, but it's been that way since assembly.

Given that the lower cable and upper case shift parts are all virtually new, am I safe to conclude my lower case (and it's shifting hardware) is the problem?

Might want go get a new prop seal and impeller kit for the spare lower... hard to say if it's smooth turning (some roughness, but I don't know if that's due to a lack of preload).

Thoughts on how to proceed?

Did some more fiddling with it. Seems the issue is a stiff lower cable. (Tried to adjust the reverse slot in reverse, and the upper cable was under a lot of compression yet the shift not slid all the way). It was stiff when first installed but it seems to have gotten worse. Shoving the cable through the housing bent the shift rod and I had to straighten it; I had to lightly use vice grips to push the cable through, the bend at the bottom was too tight?

Not yet condemning the drive since of course it won't catch reverse if the cable binds before getting there. That said, it's not enough tension to trip the shift cutoff. I got it to where FWD locks (granted, one more turn of the helm cable and it doesn't)... and RWD ratchets very hard. Hopefully good enough to get me through the rest of the season (maybe 2 outings, Labor day and end of September; the middle two weekends are booked between work and a truck show in OK)

 

[nola mike]

Did some more fiddling with it. Seems the issue is a stiff lower cable. (Tried to adjust the reverse slot in reverse, and the upper cable was under a lot of compression yet the shift not slid all the way). It was stiff when first installed but it seems to have gotten worse. Shoving the cable through the housing bent the shift rod and I had to straighten it; I had to lightly use vice grips to push the cable through, the bend at the bottom was too tight?

Not yet condemning the drive since of course it won't catch reverse if the cable binds before getting there. That said, it's not enough tension to trip the shift cutoff. I got it to where FWD locks (granted, one more turn of the helm cable and it doesn't)... and RWD ratchets very hard. Hopefully good enough to get me through the rest of the season (maybe 2 outings, Labor day and end of September; the middle two weekends are booked between work and a truck show in OK)

That cable needs to have nearly zero resistance to work right before strange things happen. It has to really bind to trip the cutout on the hard. It takes much less of a bind to mess with the shifting in the water.

 

[ratdude747]

That cable needs to have nearly zero resistance to work right before strange things happen. It has to really bind to trip the cutout on the hard. It takes much less of a bind to mess with the shifting in the water.

Sounds like I get to redo the cable job over the offseason... Yay

Not sure what went wrong other than my setup having a 90 degree bend past the shift boot and such likely bending the rod (and possibly ripping the liner) on insertion. I did use a genuine Mercruiser cable kit... and did back off the set screw before safety wiring.

 

[ratdude747]

Sounds like I get to redo the cable job over the offseason... Yay

Not sure what went wrong other than my setup having a 90 degree bend past the shift boot and such likely bending the rod (and possibly ripping the liner) on insertion. I did use a genuine Mercruiser cable kit... and did back off the set screw before safety wiring.

And now that we're in the offseason, I redid it this evening!

This time I used a Sierra kit. Partially to save a bit of money, partially to see if their product would work out better.

There were a few differences. One is that they're using a different style safety wire lug on the cable fork (single post instead of a hoop)... didn't get a pic. No biggie though, just figure-8 the wire instead of a loop.

The other difference is that instead of a coated inner wire with a metal sleeve on the end, the wire is uncoated with no cap, yet smoothed on the outside:



I used to do a lot of bicycle mechanic work, so I'm used to dealing with un-coated cables. Just grease the snot out of them and they do OK. Given that the metal sleeve on the Quicksilver cable banana'd on me (and likely a good part of why I was having binding), I'm calling this an improvement for my specific situation.

Another deviation is that I installed the cable bushing from the outside... the inside of the transom plate on my boat is inaccessible (due to having a sun deck with a shift cover, not a doghouse). Due to this poor access, it took some creativity to be able to get the chafe guard on the cable down there; the trick was to install the first few twists higher up on the cable, then slide it down the cable and wrap the rest of the way with the drive turned all the way to starboard to push the cable as far into the bilge as it will go.

Speaking of the cable, I did some looking and it seems the original (to me) cable routing wasn't correct and likely another cause of the binding. Here's what I have currently:


That's not super clear, so here's the old and new routing drawn on top:



Red is the old routing... took a hard 90° bend coming out of the transom and ran between the transom and the Y-pipe. The new is in green; the bend is a lot less severe by running between the Y-pipe and the flywheel cover. I did notice some reduction in cable resistance with the new routing, so I'm rolling with it.

On re-assembly, I discovered that I couldn't reach reverse gear at all... turns out somehow I managed to pop the shift roller off the fork. Got to pull the drive back off and try again... At least the gasket somehow survived the unplanned second removal.

Once I had the linkage issue fixed, I confirmed that the cable isn't binding (some resistance, but nothing wild like I had before) and I was also able to get the drive to fully catch both sides of the shift dogs. Had to go with max slot adjustment though. I think the shift "foot" splines may be a bit worn; I didn't take a protractor to it but it looks like it's barely within the 12° spec. Wasn't interested in popping the drive apart... so I'll keep an eye on it.

This spring, we shall see...