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Volvo Penta SP to DP lower conversion

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AKtundra

Member
I have a 280SP outdrive that I have converted to a duo prop (290 lower)
the boat hasn’t been put in water yet, but soon to be. My question is, while converting to a duo prop where should the linkage rod under the cover on the out drive be located? I have read somewhere on a forum here that it is to be in the port side (Left) now in my manual from Volvo Penta on the procedures of the conversion, they state it should be on the right hand side, or starboard.
any help here would be great, I don’t want any unforeseen surprises at a busy dock.
thanks in advance.
 
Last edited:
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AKtundra said:
I have a 280SP outdrive that I have converted to a duo prop (290 lower)
You must mean 280 s/p, as there is no 280SP.

(SP is a model that followed the 290....... and s/p = single prop)

the boat hasn’t been put in water yet, but soon to be. My question is, while converting to a duo prop where should the linkage rod under the cover on the out drive be located? I have read somewhere on a forum here that it is to be in the port side (Left) now in my manual from Volvo Penta on the procedures of the conversion, they state it should be on the right hand side, or starboard.
That would be correct!

In order to be installed correctly, any non-power trim 250, 270, 280, 285, 275 drive will be as follows;
...... a shift into FWD will always cause the shift cable to extend at the gear yoke (no coupling rod action).
...... a shift into REV will always cause the shift cable to retract at the gear yoke (pushing the coupling rod forward into the lock brace).

When the vertical linkage rod is positioned on the Stbd side, a FWD shift will cause the eccentric piston to rotate CW. This CW rotation moves the shift shoe downwards, causing the transmission's lower "driven" gear to become engaged.

With this arrangement, a single prop drive will be turning a LH propeller.
The Duo Prop lower gear unit must also be operated from the lower "driven" gear (vertical linkage rod on Stbd side).

Bottom line....... your Volvo Penta manual is correct!



Make sure that you have followed the OEM procedure taking precision A and B dimension measurements as to calculate the new shim values.

And don't forget that the gear oil now changes from 30W to GL-5 or equivalent.


Good luck...... you will like the Duo Prop's performance increase!
Click to expand...
 
Thanks Rick for the clarification. I followed the race shimming and bearing preload exactly, wasn’t to difficult as I had a variety of shims on hand. I have an older 1986 bayliner trophy 2460 with a 5.7 GM based v8 (new) and was hoping the get a little better handling and less steering torque by going to a Duo prop. I’m opting for B4 prop set to start with and see where that gets me.
you are correct..280 s/p as in single prop.
Thanks again.
 
The only problem I ran into on the lower 290 duo prop swap, was the splined shaft coupler, knowing I would need the longer sleeve, but my intermediate housing has a 1” extension plate on the bottom, after much research and trial, I was able to locate an extra long splined sleeve. I put mobile one 75/90 oil in the drive.
 
The lower duo prop unit had the shorter splined shaft, it is a 1995 Volvo Penta DP-c1 duo prop 1.95 lower unit.or it is what I was told I was buying.
when fitting it all together, my intermediate housing has a 1” extension plate on the bottom. My original splined sleeve collar was to shorty to mate the upper shaft to the lower from the duo prop unit. I ended up having to get the 4 1/8” or 4 1/4” (can’t remember right off the exact length. To make my shafts couple together..the 1” extension didn’t help this matter..
am I doing something wrong here?
 
9F75C7EA-C84F-40D3-BCE8-C74203D44983.jpg
 
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AKtundra said:
The lower duo prop unit had the shorter splined shaft, it is a 1995 Volvo Penta DP-c1 duo prop 1.95 lower unit.or it is what I was told I was buying.
The C and later units have a shortened vertical shaft, of which means that the spline coupler must be the longer one.

when fitting it all together, my intermediate housing has a 1” extension plate on the bottom. My original splined sleeve collar was too short to mate the upper shaft to the lower from the duo prop unit. I ended up having to get the 4 1/8” or 4 1/4” (can’t remember right off the exact length. To make my shafts couple together..the 1” extension didn’t help this matter..
am I doing something wrong here?
I have seen the extension/spacer used only a few times over the years. It is typically used when the transom shield X dimension is incorrect.
Personally, I would not use the extension/spacer.
Click to expand...
 
I don’t like the idea of the extension, another joint to leak,. Without it, my cavitation plate is not even or bellow the bottom of my transom. Maybe it was poor bayliner quality control?
thanks again Rick, appreciated!
 
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