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Re-installing A Standard OMC Cobra Outdrive

DavidW2009

Regular Contributor
I received a new outdrive alignment tool via UPS today. Nice looking tool. Heartland Products.

I tried it out and the tool wouldn't go into the coupling. I had previously raised the front of the engine, playing around before the tool arrived. ( I now suspect there may not have been anything wrong with the original alignment)

But I had measured and recorded where the adjust nuts were before I started. Resetting the nuts, the alignment tool went in with some resistance.

I greased the small end of the too and tried it again, not rotating the tool when removing. There were spline grease marks on the top and none on the bottom, so I raised the front of the engine a quarter turn each side. I kept tweaking it until the spline marks were even all around. The tool slid in easily and removed almost as easy, but I thought I felt something like a bit of a vacuum holding the tool. Is that possible? The coupling splines are pretty much loaded with grease by now.

Next, I try to do a dry run installing the outdrive without gasket or 'O'rings. At approximately 2" from mating with the pivot housing, the drive stops and will not go any further. I rotated the shaft, applied a little pressure while rotating the shafts, cannot make it go in. It's not even engaging the coupling.

It looks like the u-joint yoke is going into the bellows seal okay, but it is hanging on something.

I tried incrementally different elevations of the roll-around crane hoist I'm using. I have an eyebolt screwed into the top dipstick hole.

Obviously, I am missing some technique. I made sure the outdrive was straight and square with the engine. I've tried different ways to turn the u-joints. I've started all over lining things up several times. No cigar. I have read several posts on installing an outdrive and have tried to follow the instructions.

Any suggestions?
 
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First of all, the upper unit is an interference fit into the gimbal housing. It won't just slide in under the best circumstances. If there is corrosion or other gunk on the mating surfaces you will have difficulty. Second, it is possible that the splines are not matching and that will certainly give you fits. If you have a helper who can turn the engine a little either way while you apply firm forward pressure it should go far enough to get some nuts on the studs.
If the boat is on a trailer be sure to chock the wheels or you'll just be pushing the trailer and not the drive.
I think I used a tie down ratchet strap as a big clamp around the drive with some success once. Rear cover off, natch.
 
Does it feel like a solid stop or like it's hanging up? If hanging up you may want to put some grease on the outside of the u-joints as they may be hanging up inside the bellows?
 
Thanks for the reply.

The gimbal bearing is well greased. The insides of this pivot housing and the drive shaft are very clean and "new" looking. No corrosion. (There was some minor surface rust on a part of the spline that wasn't used. I cleaned that off. The spline looks very good.)

I may have to get a helper, though I'm trying to do this stuff myself. I can't tell if it's hard-stopping or just stuck on the bellows. I do need to chock the trailer tires.

How much do I need to watch the u-joints for going in straight? Or will the u-joints fall in place as the shaft lines up with the gimbal and coupling?
 
Boatin_bob,

I did put some grease on the u-joints. It's stopping , but I don't know if it's a solid stop. I'll try again tomorrow.
 
I just spent two hours analyzing this problem. I started with the alignment tool and measured all the diameters and lengths per a drawing of the tool with a calibrated Mitutoyo digital caliper. The tool is made to the drawing, (+0, -.0005"), which is acceptable. No problem with the tool.

I then carefully checked the spline pattern in the grease and made a 1/8 turn tweak to the front mounts. I have an equal pattern all the way around.

Question 1: How far up the nose of the tool should I see the spline pattern? I'm getting approx. 1" of pattern on the nose. Is this a problem?

Question 2: Should the nose of the tool go into the coupling all the way until the shoulder of the tool bottoms out on the coupling spline?
 
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It sounds to me like u still have to tweak the alignment. It doesn't take much to throw it off. If the tool only goes in an inch into the coupler than you're not even close. Don't load the tool up with grease, it's not neccessary. Too much will make it bind. You only need a thin coating. The drive shaft has to go straight into the coupler, if it's not it won't go in. In your 1st post you said the tool slid in easily. Did u tighten the motor mount before u tried to install the drive? If u didn't then the alignment was probably thrown off when u tried to install the drive. Time to start over.
 
Okay, I'll start from scratch again since the alignment tool should go all the way thru the engine coupling and bottom out on the "shoulder/step" of the tool.

I measured with a tape from the rear face of the coupling to the face of the pivot housing/bell housing mating surface. It's about 13.5". From the end of the drive shaft to the mating surface on the outdrive is approx. 16.25". The difference is 2.75". The taper on the driveshaft and the taper in the coupling spline are probably engaging a bit.

This leaves the mating surfaces of the outdrive/pivot housing about 2.25" apart, which is the gap I have when I try to re-install the outdrive. The shaft spline is not going into the coupling. I have tried turning the u-joints with a large screwdriver and the splines will not engage. (So there is still miss alignment. The alignment tool must go all the way thru the coupling easily for the driveshaft to re-install.)

So how do I know which way to adjust the front engine mounts? Trial and error? How do I determine if the coupling is too high or too low?

Thanks for your feedback. (I'm going to take this boat to the lake before the season ends. LOL)
 
Went back with a fresh look at this thing. Looked closer at the spline pattern in the grease and figured out the front mounts needed lowering. (I learned in order to get a good grease reading, the tool must be removed slowly, without touching anything, especially that seal on the front side of the gimbal bearing)

Rather than 1/4 turn increments, I lowered it 1 1/2 turns on the starboard side and 1 1/4 turns on the port side. The tool went completely in and bottomed on the front of the coupling. But the heavy spline pattern was on the bottom, so in 1/8 turn increments, both sides, I raised the front mounts (lowering the back of the engine) until I had an equal pattern all the way around and the tool fully inserted. At that point, the tool could be inserted and removed with no incumbrance except the gimbal seal.

Next, a "dry run" re-install of the outdrive (no o-rings or gasket). With some turning of the u-joints, and raising the hoist a bit, then a tweak of the engine crankshaft, the drive popped in. The most force necessary was gettin the u-joint coupling thru that seal in the drive bellows. (of course, there were no o-rings this time. With o-rings I may have to use the mounting nuts to draw it into place.)

I didn't need to use the mounting nuts to jack it in, or anything. It went in pretty easy, once past the seal.

I'll install the drive with the seals and gasket next. And move on to something else. Note: This is the first time I ever R&R'd an outdrive of any kind. It was a learning experience I hope to apply in the future if the need arises.

Here is something that I found on the 'net that helped:

proper use of an alignment bar

Your alignment tool is made up of three precisely sized shafts. The smallest fits exactly into your coupler. The next is sized small enough to pass through your bearing with room to spare, and is long enough to allow the first shaft to engage the coupler 1/2 inch before the larger shaft, sized to exactly fit the gimbal bearing contacts the bearing.

You should feel it bottom out when you slide the bar in. You want the alignment bar to slide in with very little effort and you want spiline marks to be equal all the way around the tip if the bar.

First thing you need to do is make sure your gimbal bearing is set.

Using your alignment bar insert it through the gimbal bearing and just so it starts to go into your coupler. (approx. 1/2 inch)

Using the palm of your hand, give the alignment bar a couple of "whacks" on the top,bottom and both sides of the bar. This will ensure that the gimbal bearing is at the correct angle to your coupler.

Coat the 1st 2 inches of your alignment bar evenly with grease.

Put a mark on your alignment bar near the handle so you can keep your bar in the same orientation when inputting and removing it from the coupler.

Slide the bar into the gimbal bearing and into the splines of the coupler and without twisting the bar pull it out.

You should see spline marks evenly around the end of the bar.

Are the even?

Yes.

Turn the engine over 90 degrees and check again.
Keep turning engine over in 90 deg. increments. This ensures that your coupler is centered and true.

No

Are the spline marks heavy on the top or the bottom?

If they are heavy on the top you need to Lower the front motor mounts half a turn and check again. Keep doing this step until you achieve the results listed above.

Put marks on the motor mount nuts to make sure you turn them both in the same increments.

If the heavy spline marks are on the bottom you need to Raise your front motor mounts half a turn and check again. Keep doing this step until you achieve the results listed above.

Here are some videos to help you along.

This one is showing you when its not aligned. Notice how he uses his hand to smack it in.

http://www.youtube.com/watch?v=fA5ExlPVz2w

This one shows you when everything is just right. Notice how easily the bar slides through the gimbal bearing and into the coupler.

http://www.youtube.com/watch?v=MYwnK8mjHdw
 
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Well, looks like u got 'er licked. Congrats. Put some 90w on those 0-rings. It will help the shaft to slide in a bit easier. Also, I saw on your other thread that u have a bad transom. I don't know how bad it is, but I'd go easy if u launch it. Depending on how much rot there is, the alignment may shift, damaging the coupler. Try this. Push down on the lower unit. If the transom flexes, I wouldn't launch it. But it's your call. Ever redone a transom before?
 
I plan on taking it real easy. The purpose of this launch is to functionally test all the things I've done to this project boat. I have already splashed it once, floating it on the trailer to run the engine, check the raw water system. I entirely expected the trasom to leak, but in thirty minutes of running, it didn't leak a drop!

I have tried the push down test on the outdrive several times. I can't get it to flex. Where it counts, the transom is still solid. I had a pro boat shop inspect it and give me a quote for a new transom. The shop told me the stringers and engine mounts are still good and the deck had only one minor bad spot. He said it didn't need a deck.

No, I've not done a transom before. I can get this one done using rot-proof polymer composite (forgot the brand name) for $900. Fortunately, the hull cap does not have to come off. The outdrive and engine do (not include in transom price).

I paid $400 for the boat/trailer/all safety equipment incld. Spend About $150 on it so far. With transom, I could end up with a decent running boat for less than $2,000. I want to use this boat for five years then sell it. The hour meter had 95 hours on it when I bought it. The P.O. said that was correct. The more I work on it, the more I believe it is correct.

It may be worth fixing. The biggest thing is I'm not spending a lot of money. I've been out of boating for a long time until last fall. I need to get use to boating again. If I do something stupid, at least it will be on a cheap boat. LOL.
 
That material is called Coosa board from Coosa Composites. You can also get away with using regular old exterior plywood but you have to do the epoxy encapsulation treatment (three coats of thinned resin) to it first and then bury it in glass and epoxy.
 
o2batsea,

Thanks for the feedback.

The shop quoted me both ways. Only $150 difference between plywood and composite (more $$$). A bit more labour with plywood, but less cost overall. The composite sounds easy to install. There is a slight weight savings with composite, also.
 
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Re-installation of the outdrive, with new seals and gasket, took 45 mins. and was about the same as the "dry-run" without seals.

As I was pushing the shaft in, I rotated the u-joints about one rotation CW in 1/4 turn increments. When I saw part of the u-joint coupling was not completely inside the bellows lip seal, I then rotated it CCW and it slipped right into the seal. The rest was simple and didn't require any perceiveable extra force to get the o-rings into the gimbal. The 90w gear oil helped, no doubt.

The retaining nuts did not have to be used to draw it up. The nuts were tightened following the torque sequence in two steps. Reconnected the lift cylinders and double checked everything.

Turned on the muffs and let the engine warm up. Shifted into forward and reverse slick and smooth, both in and out of gear. No noises, smooth and quiet in either gear.

Double checked the timing and idle speed and idle mixture adjust screws. Checked for leaks in engine compartment - none. Installed a new higher capacity bilge pump (justincase). I'm ready to go to the lake.

Thank you all for your input and telling me to how to do it.

BTW, I now see why it's important to check the alignment every season. If this is neglected, it makes it more difficult to do an alignment when the time comes.
 
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