Cobra Conversion To SEI 116

[TRobin9496]

I converted my Cobra outdrive to an SEI-116 yesterday using their conversion kit. I was looking for someone who had already done this to see if they had any issues with the height of the drive after the conversion. After doing the conversion, with the trim cylinders fully extended, it looks like the bottom of the outdrive is about 6" lower than old Cobra outdrive. The bottom of the Skeg is about 6" off the ground when the trailer is connected to my truck. It's so low that I'm worried about dragging the skeg when the truck suspension flexes over bumps in the road.

Has anyone else had this problem after doing the SEI Cobra conversion?

I'm trying to figure out a way to extend the trim cylinder length to allow the drive to be raised higher. When the drive is fully down(both the old one and the SEI), there's still about 3-4" of the trim cylinder ram showing, so I could extend the cylinders by about that much and still be able to lower the outdrive fully.

I know another option is to buy Alpha 1 trim cylinders, but at $400 each, that's not an option I like.

Just thought that if SEI's cobra conversion makes the drive hang that much lower in full tilt up, this should have been mentioned on their web site or in the literature.

 

[TilliamWe]

Re: Cobra Conversion To SEI 116

I am trying to understand the physics of what you are saying. From the photos of the adapter I have seen, it looks more like a stand off box than anything else. It might move the outdrive back so thet is sticks farther out behind the boat, but it shouldn't lower it. I suppose the SEI116 drive could have a lower unit that is longer than a Cobra, but not 6 inches. i think you have something hooked up or adjusted incorrectly.
Have you call SEI to ask them? They seem to be pretty helpful folks, why don't you ask them, they make the conversion?

 

[TRobin9496]

Re: Cobra Conversion To SEI 116

I'm going to ask SEI, but they're not open on weekends.

I just measured the old drive and the new one to find out what's going on. The difference is that the trim cylinder connection point on the new drive is about an inch or so farther back on the upper unit. So I lost that much length from the trim cylinder when it's extended fully. I think that losing an inch or so of travel at the connection point translates to several vertical inches at the bottom of the skeg. Also, the propshaft housing is longer on the Cobra, so the prop and skeg sit further back behind the boat, which makes them lift up higher off the ground when the trim cylinders are fully extended.

There's not much chance of hooking something up wrong with respect to this issue. I don't see more than one way to connect the trim cylinders.

FYI. Cobra trim cylinders are around 3" shorter than Alpha 1 trim cylinders.

Another option I just thought of is to lift the suspension on the trailer.

 

[JustinW]

Re: Cobra Conversion To SEI 116

We haven't had anyone mention that they thought the drive was too low when trimmed up all the way. I know the OMC trim cylinders have the eyelets on the end screwed on, so you could have some custom extensions made. Another idea, depending on your current configuration, would be to make sure you have a drop on your hitch. If you move the hitch down it will move the drive further away from the ground. Lastly, if your fenders have room for it, you could put taller tires on.

Thanks,

Justin

 

[TRobin9496]

Re: Cobra Conversion To SEI 116

Thanks for the response.

Luckily I found the problem today. I just posted this in another thread.

"Thanks for measuring. I talked to a guy at SEI today and he also measured one that they had at 23". I thought mine looked a little short at 20 1/4".

After I found out that they were short, I was expecting to find something bent or broken inside. After pulling the ram and piston assembly I quickly saw hte problem. There was a 2 3/4 plastic tube fitted around the ram which was limiting the travel to 20 1/4". I just removed the tubes, and everything works fine now...and for no $$$ spent. It was a good day.

I still can't figure out why the limiters were put in there. The only slightly feasible reason I can think of would be to prevent drive from being trimmed up too high while running. The prop of the original Cobra drive did tilt up higher due to the trim cylinder mounting holes being further forward, and the prop housing being longer, so maybe the boat was set up that way when it was new."

 

[TRobin9496]

Re: Cobra Conversion To SEI 116

Lou C, here's some of the info you were asking about on the conversion.

I just bought this boat really cheap a few weeks ago. It's the first Cobra I've had, it would have suited me just fine. I went through the outdrive before I ran it and replaced the water pump and all the seals/gaskets/o-rings(or so I thought). The seal behind the water pump, around the shaft, must have been bad and I didn't catch it with the pressure test. The upper gears flew apart after running for about 3 hrs. Learned some valuable lessons about the importance of pressure testing properly.

Anyway, I decided to go the conversion route and get the 3 yr warranty. I didn't want to be working on an old outdrive all summer.

The conversion went pretty good. It took me about 8 hrs. by myself working non-stop(yes, very sore back the next day). Here are a few notes:

1) The documentation could be better. I spent probably an hour searching for missing info in the documents.

2) The installation kit was missing 4 stainless flat washers to mount the drive onto the bellows. And one of the mounting nuts was about half the thickness of the other 5. Worked but doesn't look professional.

3) They don't give you an exhaust bellows to fit the new bell housing. The documentation said to optionally cut off the old bellows and use it. That doesn't work too well. I spent probably an hour trying to get the old bellows ribbed end(after I cut it off) around the new bell housing exhaust port. It doesn't fit well because the water hose is very close and the exhaust bellows ribs make the bellows too thick in that area. And leaving it disconnected wasn't an option for me. I had a boat with a broken exhaust bellows once, and it sounded like an old junk car with a bad exhaust when I was running it on plane.

4) The water hose took about 30 minutes to figure out. I cut it 3 times before I got it to the right length. Not really an issue, but just took some time.

5) For some reason, the pivot pins were really hard to get started without cross-threading. The old ones on the old bell housing were really easy to put in.

6) The shift selector and shift brackets on my boat were very adjustable, so that part only took about an hour and worked fine.

7) You know the trim cylinder story...that was kind of a nightmare, but didn't have anything to do with the conversion kit. I was just surprised that no one that I asked had ran across the plastic trim limits inside the cylinders before. Must be a really unique setup.

8) So far, no noise running it in the driveway. I haven't taken the boat out yet, but I plan to in the next few days. I let you know.