MD11c with MS2 reverse gear problem

[Branko]

Hi all.Desperately need help with gearbox.Here is the problem.After a long trip during which all ran fine upon return to slip forward would not disengage.It would go into neutral but it stayed in forward.I disconnected the linkage and tried shifting by hand while engine running.First time it took a few minutes for shaft to start spinning but it did.Going into neutral it stayed in forward.Shut the engine and restarted it to try with reverse first.Same thing.Shaft started to spin slow but built up speed in idle.Than it just slowed to a stop and no matter how much I moved linkage back and forth shaft would not move.It seems to engage in forward but shaft will not move.Same in reverse.It would creep but not spin.When I went to change oil gear case oil was to the top before change.I tried all this after I put new oil in engine and gear case.By the way I found gear case oil to be full to the top. Any insights would be greatly appreciated.
Regards
Branko

 

[Bill Roosa]

I am not experienced with that particular tranny but it sounds like a clutch is slipping. Clearly there is something loose as if you can put the selector in gear and nothing happens it is not the gears that are slipping.
The fact that the oil is up to the top (don't think that is right) might have something to do with it.
I'd stop the engine and put the unit in gear and try to turn the prop shaft by hand. You might be able to feel the gears engage and then tell if the clutch is in fact slipping. This is a touchy-feely thing that once you do it it is clear what your hands are feeling. a light sliding friction like what you feel when you spin a disk brake equipped wheel with the car jacked up.

The clutches are used to absorb the impact when the unit is shifted into gear. They should be able to handle the full rated load without slipping and only slip due to the impact of stopped gears engaging with engine powered ones to relieve the impact stress.

It could be a broken spring or the contact plates friction material has worn off. Kinda like a bad set of brake pads.

 

[kloudie1]

Had a problem on a friend's boat kinda like that. The transmission was a multi-plate type, the kind that requires automatic trasnsmission fluid instead of engine oil.. His transmission was filled almost to the top of the case and it behaved similar to what you are discribing .. very slow to engage and slipped easily when engaged.. His problem disappeared when we drained the oil and refilled with correct oil and amount. If your transmission is not a multi-plate one, then my post is not valid..

 

[BobM]

Seems to be a lot of confusion

...on what to use for the gear box. See:

http://www.ybw.com/forums/archive/index.php/t-262271.html

 

[kloudie1]

Woah.. Bob !! I had no idea.. Seems like Volvo is confused a bit too!

 

[Branko]

Thanks for info.Been to the boat and did hand spin test.It seems that the cone clutch is burned.I was told they don't like too much oil.I will be pulling trany out this weekend and will let all know what I find.
Branko

 

[Branko]

...on what to use for the gear box. See:

http://www.ybw.com/forums/archive/index.php/t-262271.html

OK.My MS2 is 1980 vintage.I had a thought of using AMSoil gear oil 75-90 which is fully synthetic.What are thoughts on this.Thanks.

 

[Bill Roosa]

Gear oil is extreme high pressure oil. So if all you have is gears crashing together like in a standard shift gear box with external clutch or in a differential GO is clearly a better oil. When you start adding clutches to the mix things get less clear. Clutches operate on friction so an extreme pressure oil would be the last thing you would want between the clutch plates.
So if you have a tranny with cone clutches I'm thinking you don't have a good oil to put in it. GO and the clutch does not work right, motor oil and the gears don't get the lub they need.
I'm not a fan of cone clutch trannies. Better to have some gear banging on shift once in a while and protected gears than a nice smooth shift at idle and worn gears IMO.

 

[kloudie1]

Bill is on this one ! The gear oils have friction modifiers that are designed to stick hard to the steel and ease the friction between the sliding parts.. The sliding contact of a hypoid differential specifically..some of the additive package actually corrodes a micro layer on the gear face that is tough and has a low friction coefficient.. Not what ya want in a cone clutch.. I would use the motor oil to make sure that the cone clutches engage when they are supposed to..
That stinky stuff ya smell in gear oil is the result of some sulfur compounds that do that EP (extreme pressure) lube thing with the corrosion product layer..

 

[Branko]

well gentleman here is another twist to this story.First I removed all the oil out of gearbox. I was in process of taking the bolts out but the bottom one would not budge so by accident I grabbed the shaft and felt it engage.I started playing with shifter and turning the shaft and it seemed to engage in both reverse and forward.I was totally baffled.I than decided to do a dry run by starting the engine and engaging the transmission and it did engaged in both forward and reverse.This implied that the cone clutch or as in parts list they call sliding sleeve was OK.I than put in exact amount of same as engine oil in which was 0.53 quarts.I than ran the engine for a while to warm it all up and than tried shifting by hand as in dry run.Lo and behold it engaged in both forward and reverse and shaft was spinning as soon as it would go in gear.Now what i have left to do is to connect all the linkage back and try to run the test in the slip from steering wheel..All indications are that it might work.if it works all I can say that too much oil must have created some kind of hydraulic lock and after 10 hours of running it would not disengage.
this is for all of you out there with MS2.Use exact amount of oil in it.All I got from people around the marina is "stranger things have happened".Hope they are right.
Thanks for all responses.
regards
Branko