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Old 08-06-2018, 08:22 PM   #1
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Hard to shift MS3C / TAMD40B Fix or replace??

Thanks in advance for any information or insights offered!

The problem is that my MS3C tranny always has a hard time getting into neutral (pops from one direction to the other going right through neutral - especially when cold) and occasionally gets really stuck in gear and requires (panicky) whacking on the controls to get it to shift. It does not slip or have any problems once in gear.


This is happening aboard a 1984 Kha Shing 40ft trawler that is powered with TAMD40b's which seem to run great. There are two different transmissions. Port has been replaced with a ZF 63A 2.68:1. The starboard is (original?) an MS3C 2.73:1

The port engine has been raised with blocks under the engine mounts to accommodate the 8% difference in the output shaft. There is a different coupler too I think.

I'll add here that when the engine is NOT running it shifts smoothly. It also shifts smoothly enough on the transmission itself with the linkage disconnected. However, even when shifting at the transmission it is hard to get it to stop in neutral, maybe even harder than with the gear lever at the helm. But again, when not running it shifts smoothly both at the helm and at the tranny with the linkage disconnected.

(The syncronizer has been disconnected and I am fine adjusting RPM's by ear to get them together while cruising.)

After much reading it seems like the transmission has a worn spot on the shaft on which the gear slides / changes...or something like that. I am also getting the impression that the cost of fixing it will be as high as a new / rebuilt ZF and it isn't a great transmission anyway.

Basically I just want to be able to shift comfortably. I'm comfortable replacing the transmission or taking out the old one and fixing it. If I knew the best course of action I would feel a lot better about it

Any insights offered will be much appreciated!

BTW, I've been sailing for years. I feel comfortable on any sailboat under sail or power. But I am very new to twin engines and trawlers. It is incredibly fun being up on that fly bridge I have to say.

Dan
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Old 08-06-2018, 09:38 PM   #2
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Good news for me! I was finally able to replicate the totally stuck problem to a loose screw on the control housing! It has happened three times now and this is the first time I could get it to happen again when I was able to get into the ER.

The popping from forward to reverse (and reverse to forward) without stopping in neutral is still there but I can still use the boat

The long term question is still the same though - should I be getting prepared to replace that transmission and if so thoughts about converting to ZF so they are both the same?
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Old 08-07-2018, 05:04 AM   #3
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"occasionally gets really stuck in gear and requires (panicky) whacking on the controls to get it to shift. It does not slip or have any problems once in gear."


A new shift control might solve most problems.


If you have a dual station unit (two places can shift) disconnect one as you explore.
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Old 08-07-2018, 06:43 PM   #4
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If the problem still occurs with no connection to the shift lever on the transmission then the problem must be inside the transmission, otherwise could also be controls or a sticking cable.

Ken
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Old 08-08-2018, 10:53 AM   #5
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Problem in transmission

It is hard to get it into neutral at the transmission as well. It is a little easier at the helm with the extra leverage of the controls - and the detent I imagine.

From what I've read the kind of hard 'clunking' into gear is just what the MS transmissions do. Apparently as they went up in size the design stayed the same and the additional weight of the heavier prop shafts and props makes for more wear and harder clunk into gear.

The ZF is a lot smoother and quieter when shifting. That the engine is raised up a bit doesn't seem like much of an issue. To replicate it I will have to move the fuel lines and a bit of engine room deck space but otherwise the more I look at it the less frightening it seems to do it. Except for paying for the parts

The transmissions have two slightly different gear ratio's I notice. I'm guessing one is forward and the other is reverse...If they are a little different then how does the syncronizer ever work? Even the original transmissions would have been a little different with one running clockwise and the other counter clockwise.
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Old 08-08-2018, 11:07 AM   #6
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The MS3 transmissions are mechanical and depend upon two cone clutches (one forward, one reverse) to work. I had shifting problems with both of mine, pulled one out of the boat, took it apart and de-glazed the cones with lapping compound. That was the port side transmission. For the starboard side transmission, I drained the oil, filled it with diesel fuel oil, started the engine, and shifted forward and reverse a few dozen times. Both methods worked, but the latter was a whole lot easier.
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Old 08-08-2018, 11:13 AM   #7
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And then you took out the diesel? I read somewhere that someone was running 90 gear oil instead of 20w40. What do you think of that?

Your problem was shifting? Not slipping or something like that?

I'll probably start at the gear shift (Morse) end and work down as that stripped screw at the housing isn't helping anything. But that second method sounds like a good thing to try!
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Old 08-08-2018, 08:05 PM   #8
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Yes I took out the diesel and put in 15-40 Delo 400, the same oil I use in the mains. My problem with both transmissions was difficulty in getting them in gear. Put the shifter in forward or reverse and wait for something to happen. Quite disconcerting when docking. The second method I learned from a mechanic from one of the boat yards here in San Diego. They go out of their way to help DIYers like myself.
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