View Full Version : Volvo penta lower unit replacement

06-18-2011, 08:16 AM
I have a 1995 Volvo Penta DP 5.0 motor. It was torn up the lower unit. I bought a 1990 lower unit and noticed one difference. The top shaft is a bit longer than original. everything else looks the same. some quik measurements says it close. Have I goofed and spent money on a unit that wont work? Could I just change the top shaft with shorter one? this is radical cut off a quarter inch of shaft. HELP?

06-19-2011, 11:18 AM
Volvo Penta produced the AQ series right along side of the SX and DP-S style drives from 1993 up until approx 1996, if memory serves me.
From what you are describing (short vertical shaft -vs- longer vertical shaft), may I assume that this is an AQ series drive????
Which one does it ressemble?

This is an AQ series DP-C 3 pc drive.... the good stuff! :D

This is a DP-S drive!

After the AQ series "C" drive, the lower unit vertical shaft becomes shorter, and requires a long vertical shaft spline coupler (aka splined sleeve).
Shown here is the short coupler SEQ #12 for the longer and earlier lower units.


If you have the AQ series 3 pc drive, any swapping of either Transmissions and/or Lower Units requires "Re-Shimming". The lower unit vertical shaft roller bearing race must be re-shimmed.
This is not an option..... it must be done.

Also note that your 5.0L engine dictates that the 1.95:1 ratio be used.

Post back with which drive you have.


06-21-2011, 08:04 AM
The original bad drive had the shorter shaft. The good used drive has the longer shaft. Both are 1:95 gear ratio. the longer one does bolt on and is exactly 1/4" from top spline. the coupler takes up right at 1/4". I could grind the splines in coupler back alittlle to gain alittle play. I do not want to buy another drive. I want this one to work. Am I beating at a lose cause. Had one guy say it will work without the grinding of coupler. I dont want any preasure pushing up. Thanks for the diagram and please give me help on this issue.

06-21-2011, 10:16 AM
Do NOT grind the coupler.
Many of these have a designed shear point incorporated in them... you do not want to alter this.

You have still not confirmed which drive you have.... but I'm assuming the AQ series as shown in my first image!

Why don't you post a few photos of what you have?
If you indeed have the AQ series DP, with a long vertical shaft, your solution is simple!
I have plenty of short couplers, and would be glad to send you one for the shipping cost only.

At the risk of redundancy..... I can't emphasize enough as to the importance of re-shimming the vertical shaft bearing race when changing one lower to another Intermediate housing.

We're here to help.... but ya gots to meet us half way! :)


06-21-2011, 03:44 PM
Yes I bought a boat with bad lower unit. The cost to rebuild it went way over boat value. It is the white one in picture. the boat is a 1995. I found a good lower unit off a 1990 that had a bent inner shaft. I had a good inner shaft with the pile of parts I got with 1995. I replaced the inner shaft and seals. The shaft on the one I bought is 3/4" to 1" taller. I did a trial fitting. The 2 shafts arent touching. I think they are between 1/8 to 1/4 apart from measurements I tried to make. My coupler takes up about 1/4" between the 2. If it is 1/8" then it would lift up on top baring a liitle bit. How many inches long is your coupler so I can verify which I have. If you've switch the drives which I have and never burned out the upper let me know.

About the shimming? Same gears switch out small baring for better one. My local marina robber quoted $1000.00 for shimming. Thats rediculus. I could shim all day long if I could get her apart. I started to pull lower shaft with a slide hammer. I stopped because I was afraid of what it might do to that gear inside. Whats the way to do it with $1000.00 in speciality tools. How do you pull vertical shaft and then horizonal. I am a X Ford mechanic so I can do many things mechanically. Same gears I still need shimming? Thanks so much for your help. Many say they are Volvo Penta Mechanics but the speak with to many discripencies. I just dont want to tear up what seems like pure gold parts in this new boat

06-21-2011, 04:22 PM
I just sent a PM to you.... please do not respond to it.... I included an email address and cell phone number for that.

I think that you're getting some bogus information from whoever it is that is trying to help you.
Shimming a lower to an Intermediate, with no corrosion issues, or ____, should require about 25-35 minutes tops.
I've actually had them go faster than this before... but on average, 25 minutes should be adequate.
NOTE: this is a Negative pre-load.... not POS.
The OEM specs will show you how this is done.

Re-installing the lower after the shimming is complete, requires about 15-25 minutes or so.

It takes about that long to drain and re-install the gear lube..... of which, BTW, is GL-5 for your Duo Prop..... not engine oil as with the s/p drives.

Six new O-rings and a fill plug gasket are required.

The spline couplers for these offer only two lengths, unless someone has installed a drive extension plate.

The problem with the AQ series drives in some areas of our country, is that the older mechanics have since retired, and the younger mechanics never did cut their teeth on these.
No one wants to work on them anymore, and when they are willing to, they want too much money for the task.
These are among the easiest drives to work!


06-21-2011, 05:06 PM
Hey Rick, There's some of us older guys that are still around, you and I!!