DP-C1 upper gear unit removal

I learned several years ago that it's a lot easier to just remove the upper unit instead of the whole drive, or so I thought. This time things didn't go so well. Everything was coming apart just fine until I tried to remove the unit. It wound not lift up quite enough to disengage the vertical shaft splines. I tried tilting the drive in and out a little, putting it in gear etc. but it kept binding up at the last quarter inch. Finally after about a dozen tries it came off with no problem. I'm not looking forward to another wrestling match putting this thing back together so I'm wondering if anyone has any tips or knows why it put such a fight. Thanks

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tarheeltom said:

I learned several years ago that it's a lot easier to just remove the upper unit instead of the whole drive, or so I thought
Yes, it is always easier, and it is often unnecessary to remove the Intermediate housing.

This time things didn't go so well. Everything was coming apart just fine until I tried to remove the unit. It wound not lift up quite enough to disengage the vertical shaft splines. I tried tilting the drive in and out a little, putting it in gear etc. but it kept binding up at the last quarter inch. Finally after about a dozen tries it came off with no problem. I'm not looking forward to another wrestling match putting this thing back together so I'm wondering if anyone has any tips or knows why it put such a fight. Sometimes the vertical shaft "spline coupler" wants to remain partially coupled to both the lower and upper vertical shafts while the transmission is being lifted.
What you did to eventually Un-Couple it is fairly normal.

When you go back together, the coupler will be fully seated on the lower vertical shaft splines. It should go back without issue.
Be certain that you replace all O-rings.

Click to expand...

Thank you for your reply. I'm replacing all the O-rings, PDS bearing, U-joints and shift shaft seal. Now that I have had time to think about the transmission not wanting to disengage from the vertical shaft, I think it may have had something to do with the U-joint yoke not being straight up and down with the drive

I've used a somewhat different approach to removing my 280 drive. It depends on how high the boat is from the ground and requires at least a couple of inches of ground clearance from the tipof the skeg when the drive is all the way down and latched to the pins on the transom shield.

Lift the drive and remove the clamps from the exhaust boot and the clamp at the transom shield for the drive shaft.
Disconnect the shift cable at the transmission and the entry into the drive.
REmove the water hose.

Lower the drive all the way.

Disconnect the helmet
With the drive latched on the pin on the transom shield, remove the pivot pins by driving them carefully outward.

When the pins are removed, grasp the top of the drive at the top and pull it towards you pivoting the drive on the cross pin on the transom shield (approx 30 to 45 degrees). When the drive spline is disconnected, reach under and unlatch the lock to the pin on the transom shield .... at this point it becomes a two person job as the drive is heavy and bulky.

Replacing it is just as easy. With drive boot attached at the drive end.,With a helper, pick up the drive, holding it at a negative angle, i.e. top towards you and away from the boat, and "hang" it on the transom cross pin. Hold the boot back towards the drive and support the drive shaft. As you rotate the drive forward on the transom cross pin ( sorry if I'm not using proper nomenclature) the splines on the drive shaft will be oriented correctly in 3 axis and will only need to be aligned to line up the splines. This can be done with the drive in gear by rotating the prop shaft. Once the splines engage, seat the boot onto the transom. Reconnect all the parts as usual.

Why do it this way???
1) I don't have an indoor drive in shop to work in, so I have to do this in a boat yard with wind blowing and dust swirling. Difficult to keep the drive from getting crap in it.
2) Removing the drive intact for non internals repairs
a) saves the tedious job of cleaning the mating surfaces of the upper and intermediate housing of old gaslet materials.
b) avoids the risk of spills or drips of drive lube onto the ground, which here in NJ is a "hanging offense"

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tarheeltom said:

Thank you for your reply. I'm replacing all the O-rings, PDS bearing, U-joints and shift shaft seal.
That would be the eccentric piston seal!
Please note:
..... if the shift detent's "spring pin" is parallel to the piston, you must retrieve it from it's bore!
..... this new double lip seal is directional!

Now that I have had time to think about the transmission not wanting to disengage from the vertical shaft, I think it may have had something to do with the U-joint yoke not being straight up and down with the drive.
I am not following you.
The universal drive shaft yoke will be perpendicular to the vertical shafts during disassembly.
With the stern drive powered fully down, the transmission should lift up, sideways and out easily.

Click to expand...

Side notes re; 280 vs C and later drives:
The C, C1 and C2 are a full power trim drive.
no reverse latch system.
no set pin affair.
It is much easier to R&R a shift cable while the transmission ONLY is removed.
Pull transmission first...... and if need be, remove Intermediate and lower unit afterwards.
Re-install in reverse order.


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Sandkicker, I don't think my drive is the same as yours and there is no cross pin on my transom shield to pivot the drive on but you did give me some good ideas. Thanks RicardoMarine, that little spring pin was hard for my old fat fingers to hold on to but I got it. I did this job about 7-8 years ago so I remembered basically how to do it. So far the U-joints and eccentric piston seal are done. The old piston seal was double lip but the one I received this time - OEM Volvo- was single lip. I installed it with the lip facing aft as there were no instructions. Hope I did this right. As far as the upper gear housing not wanting to come off with out a fight, I was thinking the orientation of the crosses might have had something to do with not being able to lift the gear housing straight up enough to free the splines if that is possible. I tend to confuse myself sometimes. Thanks

Re: no crosspin on later drives... true, of course. The crosspin/latch setup on the drives up to the 280 series allows a easy stable positioning of the drive. On later drives, I think (never had hands on) that the drive will still "index" on a position that will give proper alignment to the splines, however it won't be a solid lockup. Perhaps one could temporarily wire the drive to hold it in position on the lift assembly? Dunno, just thinkin' out loud...

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tarheeltom said:

Sandkicker, I don't think my drive is the same as yours and there is no cross pin on my transom shield to pivot the drive on
The 250 through 285 set pin (that Bob mentions) is a horizontal shaft that the Non-Hydraulically operated suspension fork comes up against during FWD thrust. Your C drive Suspension Fork is hydraulically operated.

All AQ series drives articulate on a "pivot tube"...... including your C drive.

Thanks RicardoMarine, that little spring pin was hard for my old fat fingers to hold on to but I got it. I did this job about 7-8 years ago so I remembered basically how to do it. So far the U-joints and eccentric piston seal are done. The old piston seal was double lip but the one I received this time - OEM Volvo- was single lip.
The new eccentric piston seal must seal against gear oil and against water. This is why they are double lip.
https://www.wholesalemarine.com/sea...2c289c&gdfms=4343C7FEFE0042F6AFE1CBFFFE7487B4

I installed it with the lip facing aft as there were no instructions.
There is a small thin area whereby the metal body is exposed. This side faces IN towards the gear oil!

Hope I did this right. As far as the upper gear housing not wanting to come off with out a fight, I was thinking the orientation of the crosses might have had something to do with not being able to lift the gear housing straight up enough to free the splines if that is possible.
In all my years of doing AQ series work, I have never experienced that!

Click to expand...

I ordered a new eccentric piston seal so it will be a few more days before I can get this thing back together. The one I got on e-bay was obviously the wrong part as it only had 1 lip so it would only seal in 1 direction. That's what I get for trying to save a few $$. Thanks again for your help.

You will not regret doing that! Be sure to install it with the exposed metal portion facing towards the gear oil side!

first gen seals were black and single lip.
second gen were brown and double lip.
next gen were green and double lip.
looks like they went back to brown.


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