OMC to Mercruiser Alpha on a 2556

[JC3]

I have a question about Bayliner 2556? Is there a way to change outdrive from OMC to Alpha? Is rebuilding an OMC possible in 2023? Thanks guys.

[builderdude]

Here’s a thread of another conversation from OMC to VP. Check it out.

https://www.baylinerownersclub.org/forum/current-topics-gc6/technical-discussion-gc12/659544-upgrading-sterndrive-engine-5-7-or-6-3

[dktool]

If you're thinking of going merc, go bravo 2
Or convert the cobra to a volvo sx as I did.
A volvo sxdp on the 2556 would be great.

I believe SEI makes a conversion adapter to put a merc leg on the cobra transom shield.

Or a complete alpha will fit the omc key hole cut out.

So many choices....

[2850Bounty]

I have a question about Bayliner 2556?
1..... Is there a way to change outdrive from OMC to Alpha?

2.... Is rebuilding an OMC possible in 2023?

1... Short answer, yes!

2... Again, short answer, yes!

OMC went belly up in around 1993 and was purchased by Volvo Penta sometime prior to 1994.
From 1994 on, all of the OMC tagged stern drives were now Volvo Penta cone clutch drives.

Here is the real question regarding the Merc A drive conversion;
Q; Why substitute one Dog Clutch drive for another Dog Clutch drive? I believe that it's counter-intuitive!


Options:

a..... do the Merc A drive conversion and maintain the dog clutch gear engagement, the SI or SA (shift interrupt/shift assist), the Gimbal suspension system, the rubber hub drive coupler, drive located seawater pump, etc.
The A drive hp limit is approx 300.

b..... go with the Merc B drive, and eliminate the SI or SA, eliminate the Dog Clutch (in lieu of Cone Clutch gear engagement) and use an engine mounted seawater pump. You will need most everything from the engine back.
The B drive hp limit is much greater.

c..... do the Volvo Penta SX (single prop) or DP-S (patented twin counter-rotating propellers) conversion and eliminate the SI or SA, eliminate the Dog Clutch (in lieu of Cone Clutch gear engagement) and use an engine mounted seawater pump.
The SX or DP-S hp limit is much greater.
With exception to the gimbal bell, I believe that you can use the OMC components from the engine back.

d.... remove all OMC drive components (from engine back) and go with the AQ series Volvo Penta DP-C 1 or 2 drive.
The hp limit is much greater.


Advantages with option D:

Enlarged transom cut-out that offers a larger transom shield foot-print against the boat's structural transom.
No more rubber hub drive coupler in lieu of an all steel Borg Warner drive coupler.

No more annual engine coupler alignment check in lieu of fixed geometry.
No Gimbal system suspension in lieu of Main suspension fork and pivot tube geometry.

Better Port to Stbd turning geometry.
No Gimbal Ring pivot issues.
No more routine Gimbal Bearing replacement in lieu of fixed geometry PDS and single bearing.
3 pc stern drive.... easy drive shaft bellows replacement.
No more Dog Clutch gear engagement in lieu of smooth Cone Clutch engagement.
No SI, SA or ESA to deal with.
No thru-propeller exhaust, in lieu of a lower unit housing exhaust outlet.
Increased re-sale value.

The DP offers 25% to 35% more thrust to the water.


However, if budget is a concern, the Merc A drive conversion will be the least expensive.



More info:

Don S August 31, 2004
If you had the DP-S drive on and working, there is no way in the world you would want to change it over to the Merc Bravo III, The DP-S is a much better and more efficient drive.


similar thread.

https://www.baylinerownersclub.org/forum/current-topics-gc6/technical-discussion-gc12/647184-converting-a-5-7-omc-cobra-to-a-volvo-225-with-the-280-duo-prop

OMC Cobra to Merc A gimbal bell conversion kit
https://www.sterndrive.cc/product/Fits-Mercruiser-Gen-II-Cobra-Conversion-Kit.html




.

[JC3]

Thank you guys!!!! I really appreciate your time, knowledge and information. If the purchase goes through I will have more questions (No doubt).

[JC3]

I wish I could (Like) each and every answer! I Really thank you guys.

[dktool]

Example only .....

https://www.ebay.com/itm/404481281827?hash=item5e2cf68f23:g:POsAAOSwjOBkr9k o&amdata=enc%3AAQAIAAAAwI7Btq9J3ZVmouEIWuxvK4zwV wh PQYe6cQsse%2Fk74qtMH7vSM0AvjQbw9rE0p%2F44MX%2Fcib5 fCHbU%2FG2qrlFxYur9BakF%2BIJhyDeQgawTLON0d7sHr9vv7 %2BDWKYTLH5bSAgnHuYqYHTp7NDhj4%2FRziNrsv16eHusgn1N kg2KuqaoU7ClaJXUJeMll2bxfRemXTR13tIGK5IefvWDhRLgYM fm6fO7IrAFhrU8I5R12iyx19bspzhGk7rIsHJZg0oq85w%3D%3 D%7Ctkp%3ABk9SR_b4tsjSYg

[JC3]

Thanks DK that helps.

[dktool]

And ....
You MUST have these parts;

The gimbal housing from the Cobra WILL NOT work.
The steering fork from the Cobra will work but the side thrust arms a much shorter, less contact surface and it would be a half-ass job.

Cobra trim rams can be made to work but not worth the effort.
The stroke is different and the mounting / pivot rods are different diameter.

https://www.ebay.com/itm/404285439634?_trkparms=amclksrc%3DITM%26aid%3D1110 006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D25405 6%26meid%3Df7f26acde31a48be81115afa23e9f3d2%26pid% 3D101429%26rk%3D5%26rkt%3D12%26sd%3D404386860156%2 6itm%3D404285439634%26pmt%3D1%26noa%3D0%26pg%3D233 2490%26algv%3DSimPLMWebV1%26brand%3DVolvo%2BPenta& _trksid=p2332490.c101429.m2460&amdata=cksum%3A4042 85439634f7f26acde31a48be81115afa23e9f3d2%7Cenc%3AA QAIAAAA8I6qvrING7O0hZFcnxkK5HPd2AAauoUtcp6gev%252B X%252F3p3YV7Gh1Ep8SA8%252BPLI%252FChtCuTvmLmeHV7KO cAGsHQMXMuC%252BxpYScrzriOhfTA53yDZqu0PD8VkA5PjSoR fV1iGyvMmF5gPSjofzSU2whOpn1zC7xxwsywbL7LyuRYGrH%25 2F0RSED5SL0GO8ecypLUhqqD4OWqKuCXqALpZEU6oUWhIffUA5 nXBCQ7Hfq1IZWu5uPMaFGa2DqW9TC0Uj5wW1nt3Qq2wdVeIpmQ vTHGfwbphvkJ0dVCH2bESPokwxjFkRq1Msrp5YP2nFEAQWmapK %252B3g%253D%253D%7Campid%3APL_CLK%7Cclp%3A2332490

The 100% correct way is this; (example only)
The shift cable exits higher on the SX shield, you came see the where the Cobra cable would exit looking at the inside picture where the unfinished area is directly below the existing cable guide housing.

https://www.ebay.com/itm/404099122919?_trkparms=amclksrc%3DITM%26aid%3D1110 006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D25405 6%26meid%3D2eb28c2d5a3b4ba9aa5afc255192652c%26pid% 3D101429%26rk%3D2%26rkt%3D12%26sd%3D404285439634%2 6itm%3D404099122919%26pmt%3D1%26noa%3D0%26pg%3D233 2490%26algv%3DSimPLMWebV1&_trksid=p2332490.c101429 .m2460&amdata=cksum%3A4040991229192eb28c2d5a3b4ba9 aa5afc255192652c%7Cenc%3AAQAIAAAA4I6qvrING7O0hZFcn xkK5HPbVj5QfLjZCxAO7cgdI9TWepBba%252FH207CL%252Fl8 r%252F2nke6xwxP%252BWx5ZCSUgLtu5K453zkG6HnsvXW%252 F0AeeAW2CPVI%252B%252BTwpO%252BQZqPRfcvVm28dY8Yhdl uNe%252FwL8kV2vTgpTmkydm9mElkVsRNZ8sJOLUJgqW4PkS7c Iy%252FWKecqd1NaxcRYUO6RcYWsRHND0u0xaynBxzEGfqbNi% 252BVjkNrIvxmhcAzzdHpz%252BBcHw2Wvcjt83yUYDHV%252F 2LQ%252FbIBHDqshEZtlwKCd4zfR26t3a5mMTAN%7Campid%3A PL_CLK%7Cclp%3A2332490

[2850Bounty]

FYI......
We Bayliner owners never got to see, or use, the later and much better Volvo Penta stern drives.... i.e., the s/p C or DP-C, DP-C1, DP-C2 and later.
By the time that these were introduced (around 1993 or so... up until 1996), Bayliner was using Mercruiser exclusively......., of which the Brunswick Corp now owned.

So, when I bring up the AQ series Volvo Penta C and later drives, most of us have had no experience with them.
This drive is very much superior to the earlier models.



For me.... the Merc A drive would be a step sideways.... but it would be affordable.
It would also be the easiest option.
The ESA, SI or SA will need to be maintained.

The OMC to Volvo Penta SX or DP-S conversion would be a good choice.... but not as affordable as the Merc A drive.
The ESA, SI or SA can be eliminated.
By the way, a good used SX or DP-S will outlast a brand new Merc A drive.

The AQ series s/p-C or DP-C would be the best choice, as I explained in my post # 4 above..... however, this would be the most expensive option.


What ever you do, it will be an improvement over that of the OMC Cobra.



.

[builderdude]

If your OMC transom assembly is in good condition then I’d think the VP SX conversion would be the easiest way to go giving you a stout drive and no shift assist stuff to deal with.
this is what Dillon did in the thread I linked in post 2.

[Metrodriver]

JC3, what is the problem with your Cobra? I rebuilt mine. All parts are available. I needed to have a shop replace one seal and bearing on the drive shaft that needed a special tool, which many shops might not have laying around anymore. Because of labor, that was the most expensive part of my boat restauration at $500.- I also needed a new ESA unit, brand new aftermarket since my original had failed. Properly adjusted it is not a bad drive. Several people here on this board run OMC, and I see a lot of boats in my neighborhood (Seattle) with them. Is it a bad drive? No. Are there better options? Yes. It depends on your budget. I got my boat for $5000 , average price is between 8000 and 10000. I spent 10000 on upgrades and repairs, total 15000. Another 6000+ for a new drive would put the boat cost at 21000. Is that worth it for a 10000 boat?

If you don't want to do the work yourself, life will get difficult. There are a few shops that can work on them, but few and far inbetween. Now it depends on where you live (which your profile does not say). The OMC needs the drive shaft alignment, the shift system alignment, shift cables that run extremely smooth. There is recurring maintenance involved. If you don't want to work on it yourself a different drive (and a lot more money) is appropriate, and many suggestions above are very good. SEI makes replacement drives for many systems, take a look at their website.
There are threads on this forum about OMC conversions, do your research.

[JC3]

Thanks Metro, I am a little long in the tooth (Just to Old) to try and do a cobra rebuild now. You had a great and helpful post and I appreciate it. I Watched a very good video of a gentleman that actually cut away part of the Cobra drive to illustrate its problems. He went with an SEI. Thanks again

[kwb]

The alpha is going to be too small of a drive for the 2556. You will want the bigger props that you can fit on a Bravo if you go with Merc.

I have no first hand experience with the conversion but OMC to Volvo has been done a lot of times with good results as far as I have read.

[builderdude]

Personally I’ve read too many problematic issues with SEI drives. If you’re going to move away from the OMC drive id think the VP SX conversion for cost would be the way to go.