SX-M Drives and counter rotation

[ConchPirate]

Bought a boat with dual VP 5.0GXi-E engines coupled to SX-M outdrives. The SX serial numbers are only 1 digit apart (4202090193 & 4202090194). Both part numbers are listed as the same (3868891). The port prop is a LH and the starboard prop a RH prop. I have read that there are VP drives that are reverse geared for port and even that some engines are made to run backwards. Is the only difference on the VP SX-M the prop, or must there be a different set of gears in the port stern drive which isn't reflected in the model/serial numbers?

 

[muc]

They are exactly the same. If you want to, you can swap the props from side to side and go forward when you put the shifter in reverse. We do it often to see if it’s a prop issue when one engine is slower then the other. Careful, it can make docking a challenge.

 

[ConchPirate]

They are exactly the same. If you want to, you can swap the props from side to side and go forward when you put the shifter in reverse. We do it often to see if it’s a prop issue when one engine is slower then the other. Careful, it can make docking a challenge.

So then where is the counter rotation of the prop shaft taking place, in the upper unit, the lower unit, or does VP run the engine backwards to achieve the prop shaft counter rotation?

 

[muc]

It is all done in the upper unit on a Volvo SX, basically you are just shifting the drive with a LH prop in reverse to go forward.

 

[ConchPirate]

It is all done in the upper unit on a Volvo SX, basically you are just shifting the drive with a LH prop in reverse to go forward.

So would that be accomplished by the helm control unit design, and everything in the outdrive stays the same for parts?

 

[muc]

That depends on what drive it is.
On a SX-M it is done at the helm control.
On some other drives, it is done by changing the linkage on the drive.

 

[72fj40]

Rotational direction should be determined by how the shift cable is connected to the upper housing on the drive. You should be able to find a factory service manual to download, either on this site or elsewhere for free. You'll find it really helpfull.

 

[muc]

Rotational direction should be determined by how the shift cable is connected to the upper housing on the drive. You should be able to find a factory service manual to download, either on this site or elsewhere for free. You'll find it really helpfull.

This is NOT correct.

 

[ConchPirate]

That depends on what drive it is.
On a SX-M it is done at the helm control.
On some other drives, it is done by changing the linkage on the drive.

That makes sense to me now. So in essence, although pushing both controls "forward" the helm control is in reality putting the port drive into reverse gear, and by using a counter rotational prop the result is forward thrust. Thanks Muc.

 

[kjk05006]

I just had to put on a new outdrive. It is a volvo penta 1.78 dp-sm.

When I shift into forward, the boat goes in reverse and vica versa.

Is there a way to change this or is the outdrive wrong? The part number is the same as the previous.