Re: Volvo Penta 280 single prop to dual prop conversion. Gear ratio question????
If your 1.61 now has a SBC or SBF V-8 in front of it, the 1.95:1 DP ratio would be the right one.
( BBC or BBF needs the 1.78:1 )
Make sure that the DP lower has its original vertical shaft bearing race with it.
Above this race is where the shimming adjustments will be made.
It must be re-shimmed when being installed on a different intermediate housing.
See your OEM service manual for the correct procedure and the A and B dimensions.
Depending on which DP lower you end up with, the vertical shaft height may be different from your 280 lower. Std shaft uses the short spline coupler. Later short shaft that needs the long spline coupler.
GL-5 gear oil is now required instead of motor oil.
These are almost cost in-effective to rebuild with new gears/bearings, so I would pull the prop shaft bearing carrier out and take a look inside be fore you lay your money down. Two bolts, a special puller, and the unit will remove.
This gives you the chance to see the three gears and several bearing surfaces.
Nothing changes to any shim values.
Cost to do this is two new O-rings and whatever you spend on a puller.
Do a forum search for Duo Prop bearing carrier pulling tool. Easy to build one.
