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Volvo 1977 MD11C MSB reverse gear shift mechanism- interchangeable with others?

cedmunds

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Does anyone out there know if there are multiple volvo penta reverse gear shift mechanisms that are interchangeable with the MSB reverse gear shift mechanism?

What the problem is:
I have MSB reverse gear and the shift mechanism is leaking oil at it's base during shifting.
Still shifts ok although a little stiff (this could be the cable). Oil level is good in the gear. I have studied the exploded view for the reverse gear and see that there is a seal in there but it does not look like it is an easy change out (for me anyway) due to the fact that the entire shift mechanism must be removed and dismantled and a hard to remove spring pin (cant find that part) holding things together.

I started thinking maybe I could find a new/used/rebuilt shift mechanism and just change out the one in there for the new/used/rebuilt one then I would have a backup and it would not matter if I screw up the one I will be trying to rebuild or have trouble finding the individual parts.

Trouble is, although I can find a few online, there is NO part number for the entire shift mechanism on the MSB exploded view to identify I would be getting the right one. There are multiple (expensive & non returnable) online that look almost exactly like it, some even having the same part number of the top plate, but they are identified for various different reverse gears (not specifically mine). I proceeded to look up the exploded views of the various volvo reverse gears identified for the shift mechanisms I found and saw that multiple of the parts listed for those did not match volvo PNs of mine. Also there is the matter of the sliding shoe (dog). I think volvo had various sizes and/or lengths of the dog depending on the reverse gear it is going into.

If there is anyone out there who is intimately familiar with the MSB shift mechanism and can tell me if there are multiples that are interchangeable with it, I would appreciate a response.

I attempted to attach exploded view of my reverse gear with shift mechanism
 

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  • MSB Reverse Gear Exploded view.jpg
    MSB Reverse Gear Exploded view.jpg
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Does anyone out there know if there are multiple volvo penta reverse gear shift mechanisms that are interchangeable with the MSB reverse gear shift mechanism?

What the problem is:
I have MSB reverse gear and the shift mechanism is leaking oil at it's base during shifting.
Still shifts ok although a little stiff (this could be the cable). Oil level is good in the gear. I have studied the exploded view for the reverse gear and see that there is a seal in there but it does not look like it is an easy change out (for me anyway) due to the fact that the entire shift mechanism must be removed and dismantled and a hard to remove spring pin (cant find that part) holding things together.

I started thinking maybe I could find a new/used/rebuilt shift mechanism and just change out the one in there for the new/used/rebuilt one then I would have a backup and it would not matter if I screw up the one I will be trying to rebuild or have trouble finding the individual parts.

Trouble is, although I can find a few online, there is NO part number for the entire shift mechanism on the MSB exploded view to identify I would be getting the right one. There are multiple (expensive & non returnable) online that look almost exactly like it, some even having the same part number of the top plate, but they are identified for various different reverse gears (not specifically mine). I proceeded to look up the exploded views of the various volvo reverse gears identified for the shift mechanisms I found and saw that multiple of the parts listed for those did not match volvo PNs of mine. Also there is the matter of the sliding shoe (dog). I think volvo had various sizes and/or lengths of the dog depending on the reverse gear it is going into.

If there is anyone out there who is intimately familiar with the MSB shift mechanism and can tell me if there are multiples that are interchangeable with it, I would appreciate a response.

I attempted to attach exploded view of my reverse gear with shift mechanism
There is an oil passage between the shifter and the reduction gear. But there is over 1/2" of gasket for the oil to get through. A more likely place for the oil leak is the rear of the reduction gear. In that case you would see oil dripping down from there. There are 2 oil seals, a U cross-section spring seal that is press fit in and a rubber wiper seal on the outside. After about 40 years use the reduction gears corrode from the inside. New units are available. A marine store in upstate N.Y., just off Lake Ontario has some. The other place oil leaks out of the transmission is into the timing gear area. Since you are not losing much oil, the seals there are probably still intact.
 
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