Volvo Penta Outdrive Interchangeablity

[dsnyder]

Hello All- I am restoring a 1978 Bayliner Saratoga Express. It is a 25 foot boat. It has a 305 V-8 engine. It also has a Volvo Penta 280 AQ Outdrive but the top half is missing. By top half, I mean the U-joint and the upper gear housing. The steering and the hull mountings are there. There was water and dirt sitting in the shaft hole that goes into the intermediate housing so I am not sure if the water was able to work its way down into the rest of the outdrive.

I was able to purchase a used, very pristine 280 AQ Outdrive that was mated to an AQ130 engine.

Now to the questions-

Could I just remove my old outdrive and bolt up the complete outdrive that was bolted to the AQ130 engine?

Will the splines be the same on both?

I would assume the gear ratios would be different because mine is a V-8 and the replacement one I have was mated to a 4 cylinder. If so, where is the gear ratio established? Is it in the top housing or the bottom housing? In other words if I just put the missing parts on my V-8 outdrive would my ratio be preserved?

If the gear ratios are different could I change props to get things to work? I plan on replacing the 305 with a rebuilt 350 in the fairly near future.

Thanks in advance for any help/advice. -Dave

 

[Scott Danforth]

there are 4 different transmissions (part you are missing). 2-bolt and 4-bolt bodies, and 10 spline or 26 spline input shaft (where it mates to the PDS). transmissions new are more than the boat is worth, however if you have patience, you can find them for a few hundred.

the lower unit of the AQ130 would have a different gear ratio than the AQ230 that you have. however physically the drives are the same dimensions

since your existing drive is full of water and dirt, that water and dirt will have gone all the way to the bottom. your looking at pulling your existing drive apart anyway.

if you plan on a 350 or even a 383, I would look at getting a 290DP drive. your 25' boat will love the DP drive, and the tilt/trim is so much nicer on the 290 than the 280. best if you replace the whole drive/transom shield assembly as a whole at that point.

 

[dsnyder]

Thanks Scott. I counted the splines. What is coming out of my engine has 10 splines and the U-Joint on what I am hoping to install also has 10 splines. I also see 4 bolt holes in my current outdrive and the new one to install also has 4 bolt holes. So from that I'm thinking it will physically fit either way. The final issue is the gear ratio. On my new until it has this number- PZ NR 2832866D. It there any way to tell what gear ratio it might have and if that ratio will work with my V-8? Thanks again!!!

 

[Scott Danforth]

gear ratio for the 4-banger wont work with your V8....ever....

 

[dsnyder]

Scott, Sorry if I am being dense here. Can I use the existing lower unit that is matched with the V-8 and mate it to the upper gear housing from the 4 cylinder and have a workable gear ratio? Is the gear ratio established in the lower unit or the upper unit?

 

[Scott Danforth]

yes, however you will have to pull it apart and may need to rebuild it since your drive is full of dirt and water as I stated in post #2. straight shot from the top to the bottom.

If your drive is full of water and it sat for more than a day or two like that, most likely you need new bearings and gears.

 

[dsnyder]

Got it! Thank you for your help. -Dave