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.

 

[Lpgc]

I'm still struggling with this.

Even thought about buying another input shaft to see if that goes through the bearing and into the coupler ok.

Today I got it to the point the end of the 6 studs were just about poking through the drive mounting holes, but only by tapping the drive with a rubber mallet. Dare not risk knocking it on any further in case it damaged the drive or coupler, tried wobbling it about but it still wouldn't go fully home. So I removed the drive again, greased up the 6 studs and holes in the drive, fitted new O rings and lubed them with engine oil, but haven't had it close to going on since.

Don't know what's wrong, the alignment bar slides right through into the coupler and I can turn it with a couple of fingers. When I put grease on the alignment bar and don't turn it the witness marks of the splines are equal all the way around the bar.

 

[Lou C]

sounds like your alignment is OK, it is really a matter of lining up the drive to the pivot housing and keeping that driveshaft totally straight as you feed it in. If they aren't lined up pretty close, it can be a real pain. Keeping the driveshaft totally straight isn't easy.
When I first started doing my own drive maintenance, I built a stand out of wood on casters that worked ok but the height wasn't easily adjustable. The adjustable drive jack is a game changer. It was well worth whatever I paid for it, I think I bought it about 13/14 years ago, it's paid for itself probably 10 times over, compared to what a shop here charges to do that, and saved my back which is even more important. The nice thing about being able to R&R your drive yourself is you find problems when they are starting, and save money from not letting things go too long like a leaky bellows.

 

[Lpgc]

I used a small ratchet strap to support the drive from stern eyes on the boat. I've got the drive almost on now, the 6 studs are all through the drive and I put a couple of nuts on slack.

But it still isn't sliding on easily. I was hoping it would just slide right up but instead of sliding easily there is still some resistance. I'm pretty sure I could tighten the 6 nuts and it would pull the drive fully on, haven't tried that yet and I don't now how much torque I'd need to put on the nuts (force on the drive) to get it to pull on. It could just be that one or more of the studs are a bit out of alignment but the studs looked straight.

I don't know now whether to try tightening those nuts (I would stop if it didn't seem to be sliding on before using a lot of torque), or pull it off and check things again, or try to wiggle it on.

Is it normal to need to pull the drive on a final bit by tightening the nuts or should it always just slide easily fully home?

When I put the prop on and put it in gear I can slightly turn the prop if I try hard enough, but it feels like I'm turning the engine (like it should if the splines are engaged OK). I've thought about disconnecting the engine coil wire and cranking the engine to see if there are any unusual noises etc, I could put the drive in gear to check that the prop turns when the engine turns... Or would that be a bad idea?

 

[Lou C]

Just thinking I forgot a few points:
1) those o rings on the driveshaft, there should not be grease in the groove that they fit in. If there is, it can believe it or not cause them to stand proud of the shaft and they won't go in the gimble bearing. When I install the new ones, I clean the grooves that the o rings fit into and lube them with motor oil only, it actually says this in my OMC shop manual.
2) the gimble bearing will be stiff like that, even brand-new ones, but I forgot to mention this:
take the alignment bar and slide it in, then rap the bar top, bottom, left and right, (use something like a rubber mallet) this helps align the bearing perfectly to accept the driveshaft, if it's off even a little it will cause the driveshaft to bind as it goes through.
And you may have to re-do this while trying to get the drive back on, because if you bump the gimble bearing with the end of the driveshaft it can knock it out of alignment.

You can see why now, some people have a real hatred of I/Os and vow to never have another one. To be fair though, you can have similar problems re-fitting outboard lower units, in fact the driveshaft can corrode in the engine flywheel and make your life a misery.
The guy who runs my boat yard is a salty old school mechanic, some years back I asked him what boat he'd recommend for our boating area:
Shamrock straight inboard, Ford 5.0 liter close cooled, Holley 4bbl carb, it came with Velvet Drive inboard transmission, and the prop is protected by the keel design. I don't see too many of these around anymore and driving them is a learned skill due to the fact that they steer very differently than an I/O or outboard.
Keep at it you'll get it.

 

[Lou C]

I used a small ratchet strap to support the drive from stern eyes on the boat. I've got the drive almost on now, the 6 studs are all through the drive and I put a couple of nuts on slack.

But it still isn't sliding on easily. I was hoping it would just slide right up but instead of sliding easily there is still some resistance. I'm pretty sure I could tighten the 6 nuts and it would pull the drive fully on, haven't tried that yet and I don't now how much torque I'd need to put on the nuts (force on the drive) to get it to pull on. It could just be that one or more of the studs are a bit out of alignment but the studs looked straight.

I don't know now whether to try tightening those nuts (I would stop if it didn't seem to be sliding on before using a lot of torque), or pull it off and check things again, or try to wiggle it on.

Is it normal to need to pull the drive on a final bit by tightening the nuts or should it always just slide easily into place?

When I put the prop on and put it in gear I can slightly turn the prop if I try hard enough, but it feels like I'm turning the engine (like it should if the splines are engaged OK). I've thought about disconnecting the engine coil wire and cranking the engine to see if there are any unusual noises etc, I could put the drive in gear to check that the prop turns when the engine turns... Or would that be a bad idea?

I know where you're at, and it's because the drive is so heavy, you really can't get it in good enough alignment to get it to slide on, you need a stand to support it at the right height.
When I have mine lined up, it slides right on, like within 1/8" of the 2 mating surfaces touching.
You can carefully try to pull it on with the 6 nuts, but if it won't go, you have to stop and start again. I would not use more than about 25-50 ft lbs to tighten it. Start with 25, then go up to 50, tighten the center nuts first then go to the others in a criss cross pattern. If that gets it, then good.

Now you can see why so many outdrives are neglected and never get pulled until there is a major problem, and that's about the worst thing you can do! It can get to the point where it will NOT come off no matter what due to the driveshaft corroding into the coupler splines. All from a lack of maintenance.
If you want to keep this boat for a long time I'd either buy the drive jack I am using or, build a custom one that will work with the height of your transom mount.
If the trailer is too low to get the drive lined up right, you can try lowering the front of the boat with the tongue jack, or put blocks under the tires to raise it up so you can get the alignment of the transom mount and drive perfect.
I got lucky on mine the roller trailer carries the boat a bit high so get it lined up is no problem. I did lower the boat a bit by using different brackets for the crossmembers because it used to be too high.

Boat Outdrive Jack

BOAT LOWER UNIT JACK with "BRAKE" Casters $325.00 ( Part # BLU-JL ) ( color may very )

www.stumpysfabworks.com

$325 USD and worth every penny
It saved my back and a LOT of money if I couldn't do this myself.

when I started pulling/installing the drive I was about 52 or so, now I'm about to turn 71 and there is NO WAY I'd be struggling to do this without the right "tools"!

 

[Lpgc]

1. I did that - Removed the old O rings, cleaned up the recesses, fitted new Orings. When I slid the new O rings up the shaft they got coated with grease from the splines but I cleaned them up before putting them in the recesses. Coated them with engine oil.

2. I didn't try moving the axis (don't know the correct term) of the old gimble bearing before I removed it, I did try to move the axis after I'd removed it but it seemed stuck. There was a bit of rust on the parts that allow the axis to change which I thought might have been a problem. I didn't try to adjust the axis of the new bearing before installation, after installation I tried to move the axis using the alignment tool but it was very stiff. The alignment tool slid through the bearing into the splines easily and when I did the grease witness marks check it seemed OK... But after a couple of attempts at drive installation when I tried rotating the alignment tool in the coupler splines the alignment tool seemed to rotate off-centre, so I wonder if I moved the gimble bearing off centre when trying to install the drive.