1996 OMC Cobra / Volvo SX gaskets

[Lpgc]

The boat is a 1996 Four Winns Sundowner 205 5.0 Ford with the OMC Cobra / Volvo SX collaboration setup.

Today I removed the drive and changed the gimble bearing.

Now I need new gasket(s) to refit the drive but I'm not sure what gaskets I need. I have had the drive off and changed the gaskets before but that was over 2 years ago. I forget which gaskets were the correct ones, I bought incorrect gaskets before getting it right last time.

A pic of the transom components with drive removed.



Are the gaskets in this link correct for this drive? https://repowermarine.com/outdrive-mounting-gasket-for-volvo-penta-sx-omc.html . If so do I need any other gaskets?

This is a long running thread I started shortly after buying the boat https://forums.iboats.com/threads/1996-four-winns-sundowner-with-5-0-cobra-engine-and-drive.766501/

 

[Lou C]

Looks like it. That style of drive is just like the Volvo SX so it does not use a gasket between the pivot housing & outdrive like the original dog clutch Cobra does. Only the irregular shaped oring for the water passage area. The 2 orings are for the driveshaft.

 

[Lou C]

I would though coat the edges of the pivot housing & drive where they join together with marine grease.

 

[Lpgc]

Looks like it. That style of drive is just like the Volvo SX so it does not use a gasket between the pivot housing & outdrive like the original dog clutch Cobra does. Only the irregular shaped oring for the water passage area. The 2 orings are for the driveshaft.

Thanks Lou, I wondered what the 2 Orings were for!

I would though coat the edges of the pivot housing & drive where they join together with marine grease.

Yeah I did that last time I had the drive off.

I changed the gimble bearing because it's not been done in my ownership and I don't know when it was last done. A couple of times I've thought I heard a strange noise that could've been a failing gimble bearing. But the old bearing I just removed seems in good condition. The new bearing is a sealed unit, no need to grease it.... Are the sealed units generally considered better or worse than the old type?

Alignment seemed to check OK, the tool slotted through the bearing straight into the engine coupler and I can rotate the tool without much resistance. But I don't know if that's a good enough check, it occurs to me that since the coupler is rubber and the engine hasn't been run for around a month the rubber could have 'taken' / bent into a position where the tool would slide in easily but still be out of alignment when the coupler is rotated - Should I rotate the engine 90 and 180 degrees to check alignment with the coupler rotated?

 

[Lou C]

So when you check the alignment you are supposed to coat the very last part of it that goes into the splines with grease, insert the tool (do not rotated it, put it in straight and pull it out straight) and look at the 'witness marks' the coupler makes in the grease, it should look the same all around. That's what really tells you if it's aligned properly.

 

[Lou C]

PS you can repeat the test with it rotated 90* and 180* but I just usually check it once whenever I have the drive off.
I have not had to change it in YEARS.

 

[Lpgc]

So when you check the alignment you are supposed to coat the very last part of it that goes into the splines with grease, insert the tool (do not rotated it, put it in straight and pull it out straight) and look at the 'witness marks' the coupler makes in the grease, it should look the same all around. That's what really tells you if it's aligned properly.
View attachment 420722

Thanks, that's what I had forgotten.

 

[Lpgc]

I also forgot what type of grease to use on the driveshaft UJ joints... Is it the really thick sticky marine stuff or same spec as used for trailer wheel bearings?

 

[Lou C]

Either will work; I use Lucas Marine grease but ujoints aren’t super picky like wheel bearings are, just keep em dry and lubed and don’t trim it too high unless at slow idle.

 

[Lpgc]

I had another look at the gimble bearing I removed today, it spins freely with no noise or play so seems good in that respect... But it is very stiff to change the angle / axis of the inner in relation to the outer. How much force is it supposed to take to change the axis? I wonder if the stiffness may be the cause of some of the noises and vibration the boat had at certain rpm / throttle positions.

I can feel a bit of wear on the drive input shaft around the area where it seats in the gimble bearing and the shaft is shiny around that area. The old bearing still seats on the shaft with very minimal clearance, I cannot waggle the old bearing on the shaft. Pic of the shaft below, does this look OK?






I was waiting for a new gasket arriving before reinstalling the drive, turns out I already have a new gasket so I'm putting it back together today., have already regreased the Ujoints etc.

 

[Horigan]

I would run it. If it still vibrates, then look at a new shaft, though it's likely part of the U-joint assembly. Note that you grease the splines, but put motor oil on those O-rings during installation.

 

[Lpgc]

I've been trying to refit the drive for the last 90 minutes.

At one point I had it nearly done, had the spines engaged and the 6 bolts halfway through the holes in the drive, just couldn't get it to move that final bit.

Since then I've struggled to get it even engaged with the splines in the engine coupler.

The trailer and boat design don't help... The drive won't go all the way down before it touches the ground when it's on the trailer. The boat bathing platform goes over the drive and the transom is inset from the rearmost part of the boat, makes getting in to jiggle it around difficult.

Starting to get dark so after a bit of a rest I'll have another couple of goes but if it doesn't go on I'll have to leave it tonight and come back to it tomorrow afternoon.

What do the Orings do? Does one of them go through the gimble bearing?

The drive came off very easily, the alignment seemed good when I checked the spline grease imprints on the alignment tool, I knew refitting it would involve some jiggling of the heavy drive and be hard work but still thought refitting it would be a lot easier than this.

 

[Lpgc]

Adding to my last post, I got it this far (pic below) but I'm struggling to get it the rest of the way on.



Any ideas what it could be sticking on?

 

[Lou C]

Ahh I have fought that fight a few times, what happens is a couple of things:
the u joints because it's a double cardan style get out of alignment, meaning that the shaft isn't straight, and then it doesn't go in straight, so the end of it is hitting the outer edge of the coupler but doesn't go in
OR
it's really close to going it but the splines don't line up, you'd think they should because it slid off so easily
I use a drive jack to get the height as close to perfect as I can and also make sure that the mating edges of the drive and pivot housing are parallel to each other. And try my best to feed the driveshaft in straight. If it goes in almost all the way I will take a long thin screwdriver and stick it in the opening of the ujoint and use it to just slightly turn the driveshaft, sometimes all it takes is 1/8th" and it slides right in.
In your pic you can see the mating surfaces aren't quite parallel. I have fought this so many times I actually use a level to get both level lol.
Anyhow those are the tricks I have learned in 20 years of R&R a Cobra outdrive.
Drive jack, worth it's weight in gold, because it prevents back injuries..





Yeah it's ugly but 25 years in the salt and I'm too lazy to strip it down to the alu!
Anyway that's how I do it.

The drive jack I bought from a place out in the midwest called Stumpy's Fab Works, it is REALLY nice to have, when I pull the drive for the season I just leave it on the jack in the garage for the winter.
I've done this so many times now it usually doesn't take me more than 10 minutes.
Remember lining up the splines is kind of like using a clutch alignment tool if you are changing a clutch on a manual transmission car. Normally it should not change, but for some reason it can be ever so slightly off, and it won't go on that last inch or so.